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JNL: ROP PIPS: 295858 TYPE: PAPTS: NEWGEN DATE: 10/6/2009EDITOR: MJIOP PUBLISHINGREPORTS ON PROGRESS IN PHYSICSRep. Prog. Phys. 72 (2009) 000000 (185pp)UNCORRECTED PROOFPhysics at a future Neutrino Factory andsuper-beam facilityThe ISS Physics Working GroupEditors: S F King1, K Long2, Y Nagashima3, B L Roberts4and O Yasuda51School of Physics and Astronomy, University of Southampton, Highfield, Southampton S017 1BJ, UK2Department of Physics, Blackett Laboratory, Imperial College London, Exhibition Road, London, SW7 2AZ, UK3Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan4Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA5Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, JapanA Bandyopadhyay1, S Choubey1, R Gandhi1, S Goswami1, B L Roberts2,J Bouchez3, I Antoniadis4, J Ellis4, G F Giudice4, T Schwetz4,S Umasankar5, G Karagiorgi6, A Aguilar-Arevalo6, J M Conrad6,M H Shaevitz6, S Pascoli7, S Geer8, J E Campagne9, M Rolinec10,A Blondel11, M Campanelli11, J Kopp12, M Lindner12, J Peltoniemi13,P J Dornan14, K Long14, T Matsushita14, C Rogers14, Y Uchida14,M Dracos15, K Whisnant16, D Casper17, Mu-Chun Chen17,64, B Popov18,J¨Ayst¨ o19, D Marfatia20, Y Okada21, H Sugiyama21, K Jungmann22,J Lesgourgues23, M Zisman24, M A Tortola25, A Friedland26, S Davidson27,S Antusch28,65, C Biggio28, A Donini28, E Fernandez-Martinez28,B Gavela28, M Maltoni28, J Lopez-Pavon28, S Rigolin28, N Mondal29,V Palladino30, F Filthaut31, C Albright32,64, A de Gouvea33, Y Kuno34,Y Nagashima34, M Mezzetto35, S Lola36, P Langacker37, A Baldini38,H Nunokawa39, D Meloni40, M Diaz41, S F King42, K Zuber43,A G Akeroyd44, Y Grossman45, Y Farzan46, K Tobe47, Mayumi Aoki48,H Murayama49,50,51, N Kitazawa52, O Yasuda52, S Petcov53, A Romanino53,P Chimenti54, A Vacchi54, A Yu Smirnov55, E Couce56,J J Gomez-Cadenas56, P Hernandez56, M Sorel56, J W F Valle56,P F Harrison57, C Lunardini58, J K Nelson59, V Barger60, L Everett60,P Huber60, W Winter61, W Fetscher62and A van der Schaaf631Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019, India2Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA 02215, USA3Service de Physique des Particules, CEA – Saclay, F-91191 Gif sur Yvette Cedex, France4Department of Physics, CERN Theory Division, 1211 Geneva 23, Switzerland5Institute of Mathematical Sciences, Taramani, C.I.T. Campus, Chennai 600113, India6Department of Physics, Columbia University, New York, NY 10027, USA7Department of Physics, University of Durham, Ogen Center for Fundamental Physics, South Road,Durham, DH1 3LE, UK8Fermilab, Batavia, IL 60510-0500, USA9LAL, Universit´ e Paris-Sud 11, Bˆ atiment 200, F-91898 Orsay cedex, France10Physik-Department T30d, Technische Universitaet Muenchen, James-Franck-Strasse, 85748 Garching,Germany11Departement de Physique Nucleaire et Corpusculaire (DPNC), Universite de Geneve, Geneve,Switzerland12Max-Planck-Institut f¨ ur Kernphysik, Saupfercheckweg 1, 69117, Heidelberg, GermanyAQ164Also at: Theoretical Physics Department, Fermilab, Batavia, IL 60510-0500, USA.65Alsoat:Max-Planck-Institutf¨ urPhysik(Werner-Heisenberg-Institut), F¨ ohringerRing6, 80805M¨ unchen, Germany.0034-4885/09/000000+185$90.001© 2009 IOP Publishing LtdPrinted in the UK
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Rep. Prog. Phys. 72 (2009) 000000 A Bandyopadhyay et al13Centre for Underground Physics in Pyh¨ asalmi, Universty of Oulu, Oulu, Finland14Imperial College London, Blackett Laboratory, Department of Physics, Exhibition Road, London,SW7 2AZ, UK15Centre de Recherches Nucleaire, Hautes Energies, Institut National de Physique Nucleaire et desParticules, Universite Louis Pasteur, Paris, France16Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA17Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA18Joint Institute for Nuclear Research, Joliot-Curie 6, 141980, Dubna, Moscow Region, Russia19Jyvaskyla University, Finland20Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA21Theory Group, KEK, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan22KVI, Groningen, The Netherlands23Laboratoire de Physique Theorique, LAPTH, F-74941, Annecy-le-Vieux Cedex, France24Lawrence Berkeley National Laboratory, Physics Division, 1 Cyclotron Road, 50R4049, Berkeley,CA 94720-8153, USA25CFTP and Departamento de Fisica, Instituto Superior Tecnico. Av. Rovisco Pais, 1049-001 Lisboa,Portugal26Los Alamos National Lab, PO Box 1663, Los Alamos, NM 87545, USA27IPN de Lyon, Universit´ e Lyon 1, CNRS, 4 rue Enrico Fermi, Villeurbanne, F-69622 cedex France28Departamento de Fisica Teorica (IFT), Facultad de Ciencias C-XVI, Universidad Autonoma de Madrid,UAM-CSIC, Cantoblanco, Madrid 28049, Spain29Tata Institute of Fundamental Research, School of Natural Sciences, Homi Bhabha Road, Mumbai400005, India30Universit` a Federico II and INFN Napoli, Italy31Katholieke Universiteit Nijmegen, HEFIN - High Energy Physics Inst., PO Box 9010, NL-6500 GLNijmegen, Netherlands32Department of Physics, Northern Illinois University, DeKalb, IL 60115, USA33Northwestern University 633 Clark Street Evanston, IL 60208, USA34Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan35Dept. di Fisica, Univ. di Padova, via Marzolo 8, I-35100 Padua, Italy36Department of Physics, University of Patras, GR-26100 Patras, Greece37Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA38INFN Pisa, Italy39Departamento de F´ ısica, Pontif´ ıcia Universidade Cat´ olica Ddo Rio de Janeiro, C. P. 38071, 22452-970,Rio de Janeiro, Brazil40INFN and Dipto. di Fisica, Universit` a degli Studi di Roma 'La Sapienza', P.le A. Moro 2, 00185, Rome,Italy41Departamento de Fisica, Universidad Catolica de Chile, Avenida Vicuna Mackenna 4860, Santiago,Chile42School of Physics and Astronomy, University of Southampton, Highfield, Southampton S017 1BJ, UK43Department of Physics and Astronomy, University of Sussex, Falmer, Brighton, Sussex BN1 9QH, UK44Department of Physics, National Cheng Kung University, Tainan 701, Taiwan45Department of Physics, Technion, Haifa 32000, Israel46Institute for Studies in Theoretical Physics and Mathematics, PO Box 19395-1795, Tehran, Iran47Department of Physics, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578, Japan48Theory Group, Institute of Cosmic Ray Research, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa,Chiba 277-8582, Japan49Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Japan 277-856850Berkeley Center of Theoretical Physics, University of California, Berkeley, CA 94720, USA51Theoretical Physics Group, Lawrence Berkeley National Laboratory, MS 50A-5104, Berkeley,CA 94720, USA52Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan53International School for Advanced Studies (SISSA/ISAS), via Beirut 2-4, I-34100 Trieste, Italy54INFN presso il Dipartimento di Fisica dell'Università di Trieste, Via Valerio, 2, I - 34127 Trieste, Italia55Abdus Salam International Centre for Theoretical Physics Strada Costiera 11, I-34014 Trieste, Italy56Instituto de F´ ısica Corpuscular, IFIC, CSIC and Universidad de Valencia, Spain57Department of Physics, University of Warwick, Coventry, Warwickshire, CV4 7AL, England58Institute for Nuclear Theory and Department of Physics, University of Washington, Seattle, WA 98195,USA59Department of Physics, College of William and Mary, PO Box 8795, Williamsburg, VA 23187-8795,USAAQ22
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Rep. Prog. Phys. 72 (2009) 000000 A Bandyopadhyay et al60DepartmentofPhysics, UniversityofWisconsin, 2506SterlingHall, 1150UniversityAvenue, Madison,WI 53706, USA61Universit¨ atW¨ urzburg,LehrstuhlfurTheoretischePhysikII,AmHubland,D-97074W¨ urzburg,Germany62ETH, Z¨ urich, Switzerland63Physik-Institut der Universit¨ at Z¨ urich, SwitzerlandReceived 15 October 2008, in final form 4 January 2009PublishedOnline at stacks.iop.org/RoPP/72AbstractThe conclusions of the Physics Working Group of the international scoping study of a futureNeutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried out bythe international community between NuFact05, (the 7th International Workshop on NeutrinoFactories and super-beams, Laboratori Nazionali di Frascati, Rome, 21–26 June 2005) andNuFact06 (Ivine, CA, 24–30 August 2006). The physics case for an extensive experimentalprogramme to understand the properties of the neutrino is presented and the role ofhigh-precision measurements of neutrino oscillations within this programme is discussed indetail. The performance of second-generation super-beam experiments, beta-beam facilitiesand the Neutrino Factory are evaluated and a quantitative comparison of the discoverypotential of the three classes of facility is presented. High-precision studies of the properties ofthe muon are complementary to the study of neutrino oscillations. The Neutrino Factory hasthe potential to provide extremely intense muon beams and the physics potential of suchbeams is discussed in the final section of the report.(Some figures in this article are in colour only in the electronic version)AQ3Executive summaryTheinternationalscopingstudyofafutureNeutrinoFactoryandsuper-beamfacility(theISS)wascarriedoutbytheinternationalcommunity between NuFact05, (the 7th International Workshop on Neutrino Factories and super-beams, Laboratori Nazionalidi Frascati, Rome, 21–26 June 2005) and NuFact06 (Ivine, CA, 24–30 August 2006). The physics case for the facility wasevaluated and options for the accelerator complex and the neutrino-detection systems were studied. The principal objectiveof the study was to lay the foundations for a full conceptual-design study of the facility. The plan for the scoping study wasprepared in collaboration by the international community that wished to carry it out: the ECFA/BENE network in Europe,the Japanese NuFact-J collaboration, the US Neutrino Factory and Muon Collider collaboration and the UK Neutrino Factorycollaboration. STFC's Rutherford Appleton Laboratory was the host laboratory for the study. The study was directed by aProgramme Committee advised by a Stakeholders Board. The work of the study was carried out by three working groups:the Physics Group; the Accelerator Group; and the Detector Group. Four plenary meetings at CERN, KEK, RAL and Irvinewere held during the study period; workshops on specific topics were organized by the individual working groups in betweenthe plenary meetings. The conclusions of the study were presented at NuFact06. This document, which presents the PhysicsGroup's conclusions, was prepared as the physics section of the ISS study group. More details of the ISS activities can be foundat http://www.hep.ph.ic.ac.uk/iss/.Neutrino oscillations are the sole body of experimental evidence for physics beyond the Standard Model of particle physics.The observed properties of the neutrino—the large flavour mixing and the tiny mass—are believed to be consequences ofphenomena which occur at energies never seen since the Big Bang. Neutrino facilities to pursue the study of oscillationphenomena are therefore complementary to high-energy colliders and competitive candidates for the next world-class facilitiesfor particle physics. Neutrino oscillations also provide a window on important issues in astrophysics and cosmology. Ongoingand approved experiments utilize intense pion beams (super-beams) to generate neutrinos. They are designed to seek andmeasure the third mixing angle θ13of neutrino-mixing matrix (the 'PMNS' matrix), but will have little or no sensitivity tomatter–antimatter symmetry violation. Several neutrino sources have been conceived to reach high sensitivity and to allow therange of measurements necessary to remove all ambiguities in the determination of oscillation parameters. The sensitivity ofthese facilities is well beyond that of the presently approved neutrino oscillation programme. Studies so far have shown thatthe Neutrino Factory, an intense high-energy neutrino source based on a stored-muon beam, gives the best performance overvirtually all of the parameter space; its time scale and cost, however, remain important question marks. Second-generationsuper-beam experiments using megawatt proton drivers may be an attractive option in certain scenarios. Super-beams havemany components in common with the Neutrino Factory. A beta-beam, in which electron-neutrinos (or anti-neutrinos) areproduced from the decay of stored radioactive ion beams, in combination with a second-generation super-beam, may be acompetitive option.3
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et alThe role of the ISS Physics Group was to establish the strong physics case for the various proposed facilities and to findoptimum parameters for the accelerator and detector systems from the physics point of view. The first objective of this report,therefore, is to try to answer the big questions of neutrino physics; questions such as the origin of neutrino mass, the role thatneutrinos played in the birth of the universe and what the properties of the neutrino can tell us about the unification of matterand force. These questions form the basis for the clarification of the physics cases for various neutrino facilities. Since it is not(yet) possible to answer these questions in general, studies have concentrated on more specific issues that may lead to answersto the big questions. In particular, studies have addressed such issues as:1. The relevance of neutrino physics to the understanding of dark matter and dark energy, the connection between neutrinomass and leptogenesis and galaxy-cluster formation;2. The connection of predictions at the grand-unification scale with low-energy phenomena in the framework of see-sawmechanism and supersymmetric extensions of the Standard Model and3. The understanding of flavour and the connection between quarks and leptons, the possible existence of hidden flavourquantum numbers that may be connected with the small mixings among the quarks, the mass hierarchy of the quarks andcharged leptons and the relationship of these phenomena with the neutrino-mass matrix.The second objective of this report is to review the predictions of the various models for the physics that gives rise to neutrinooscillationsandtoreviewtheassociatedphenomenologythatisrelevantforprecisionmeasurementsofneutrinooscillations. Forthis purpose, we have evaluated the degree to which the various facilities, alone or in combination, can distinguish between thevarious models of neutrino mixing and determine optimum parameter sets for these investigations. A class of directly-testablepredictions is afforded by the fact that the GUT and family symmetries result in relationships between the quark- and lepton-mixing parameters. These relationships can be cast in the form of sum rules. One example that can be used to discriminateamongst various models is:θ?12≡ θ12− θ13cos(δ),where θ?small mixing angle and the cosine of the CP-violating phase) are measured experimentally. Another class of test is afforded bythe investigation of the unitarity of the PMNS matrix. While the quark-mixing (CKM) matrix is constrained to be unitary inthe Standard Model, the PMNS matrix, which originates from physics beyond the Standard Model, may not be exactly unitary;this is the case, for example, in see-saw models. The third class of the test is the existence of flavour-changing interactions thatmight appear at the production point, in the oscillations that occur during propagation, or at the point of detection. The possiblestrong correlations between lepton-flavour violation and neutrino oscillations are also discussed.The potential of non-accelerator, long-baseline neutrino oscillation measurements were also considered.improvements in the precision with which the solar parameters are known could be made using a new long-baseline reactorexperiment or by using gadolinium loading of the water in the Super-Kamiokande detector to increase its sensitivity to solarneutrinos. A large, underground, magnetized-iron detector could be used to improve the precision of the atmospheric mixingparameters, to determine the octant degeneracy and to search for deviations from maximal atmospheric mixing.The third, and key, objective of this report is to present the first detailed comparison of the performance of the various facil-ities. Using realistic specifications, we have estimated the likely performance, tried to find optimum combinations of facilities,baselines and neutrino energies, and attempted to identify some staging scenarios. The cases considered are described in detailin the main report; only a brief summary is given here. Although the Neutrino Factory can achieve very large data samples withsmallbackgrounds,itoperatesatenergiesconsiderablyhigherthanthefirstoscillationpeak(Emax/GeV = L/564km). Becauseof this, at intermediate values of θ13(10−3? sin22θ13? 10−2) the Neutrino Factory with only one golden-channel (νe→ νµand ¯ νe→ ¯ νµ) detector (at, say, 4000km) cannot resolve all parameter degeneracies and the precision of the measurement ofa particular parameter is reduced by correlations among the parameters. These problems can be resolved in one of three ways:12can be predicted in classes of flavour models while θ12(the solar mixing angle) and θ13cos(δ) (the product of theSignificant1. Placing a second detector at a different baseline (i.e. varying the ratio L/E);2. Adding a detector sensitive to the silver channel (νe→ ντ) or3. Using an improved detector with lower neutrino-energy threshold and better energy resolution.Possible configurations for each alternative, alone and in combination, were investigated to find an optimum performance ofthe Neutrino Factory. It was shown that a considerable reduction of parent muon energy down to ∼25GeV is feasible withouta significant loss of oscillation-physics output, provided a detector performance improved with respect to the one assumed inearlier studies can be achieved.To make direct, quantitative comparisons of the various facilities, the GLoBES package was used. Three representativesuper-beam configurations were considered: the SPL, a super-beam directed from CERN to the Modane laboratory; T2HK, anupgrade of the J-PARC neutrino beam illuminating a detector close to Kamioka, and the WBB, a wide-band, on-axis beamfrom BNL or FNAL to a deep underground laboratory in the US. Each super-beam was assumed to illuminate a megaton-classwater Cherenkov detector. The beta-beam options considered were the CERN baseline scheme in which helium and neon ionsare stored with a relativistic γ of 100 and an optimized beta-beam for which γ = 350. Two Neutrino Factory options wereconsidered: a conservative option with a single 50kton detector sited at a baseline of 4000km from a 50GeV Neutrino Factory;4
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Rep. Prog. Phys. 72 (2009) 000000 A Bandyopadhyay et aland the optimized Neutrino Factory (see the full report) with two detectors, one at a baseline of 4000km and the second atthe magic baseline (∼7500km). The result of the comparisons may be summarized as follows: for the options considered, theNeutrino Factory has the best discovery reach for sin22θ13followed by the beta-beam and the super-beam, while the sin22θ13reach for resolving the sign of the atmospheric mass difference is mainly controlled by the length of the baseline. For largevalues of θ13(sin22θ13? 10−2), the three classes of facility have comparable sensitivity for the discovery of CP violation; thebest precision on individual parameters being achieved at the Neutrino Factory using optimized detectors. The reduction ofsystematic uncertainties is the key issue at large θ13; by reducing systematic uncertainties, the super-beam may be favourablycompared with the conservative Neutrino Factory. For intermediate values of θ13(10−3? sin22θ13? 10−2), the super-beamsare outperformed by the beta-beam and the Neutrino Factory and the best CP coverage is achieved by the beta-beam. For smallvalues of θ13(sin22θ13? 10−3), the Neutrino Factory outperforms the other options. Note that the comparisons are made usingthree performance indicators only (sin22θ13, the sign of mass hierarchy and the CP-violating phase δ). If other physics topics,such as the search for e,µ,τ flavour anomalies, were to be emphasized, the relative performance may be different.The final contribution to this report reviews the muon physics that can be performed with the intense muon beams that willbe available at the Neutrino Factory. The study of rare, lepton-flavour-violating processes in muon decay, and the search for apermanentelectric-dipolemomentofthemuon,arecomplementarytoprecisionstudiesofneutrinophysics;oftensensitivetothesameunderlyingphysics. Thecomplementarityandthepotentialofamuon-physicsprogrammeattheNeutrinoFactoryisinves-tigated. It will be important in the coming years to establish quantitatively the synergy between muon physics and the study ofneutrinooscillationsandtodevelopaplanfortheco-existenceofmuonandneutrinoprogrammesattheNeutrinoFactoryfacility.A significant amount of conceptual design work and hardware R&D is required before the performance assumed for eachof the facilities can be realized. Therefore, an energetic programme of R&D into the accelerator facilities and the neutrinodetectors must be established with a view to the timely delivery of conceptual design reports for the various facilities.Contents1. Introduction1.1. Neutrino in a nutshell1.2. Neutrino physics as part of the high-energyphysics programme1.3. Implications and opportunities1.4. Precision measurements and sensitive searches1.5. What the study tried to achieve2. The standard neutrino model2.1. Introduction2.2. Review of the present generation of experiments 152.2.1. Solar- and reactor-neutrino experiments 152.2.2.Atmospheric-neutrino experiments2.2.3. Long-baselineexperiments220.127.116.11νββ experiments2.2.5. Recent progress in measurements ofneutrino oscillations2.3. Completing the picture2.3.1. Bounds on θ13from approvedexperiments2.4. Degeneracies and correlations2.4.1. Appearance channels: νe → νµ,ντand νµ→ νe2.4.2.Disappearance channels: νµ→ νµ2.4.3. A matter of conventions2.4.4.Disappearance channels: νe→ νe3. Implications for new physics and cosmology3.1. The origin of small neutrino mass3.1.1. See-saw mechanisms3.1.2.Supersymmetry and R-parity violation3.1.3. Extra dimensions3.1.4.String theory3.1.5. TeV-scale mechanisms for smallneutrino masses77781011121216neutrino-oscillation17202222222323252627272828293133353.2. Unification and flavour3.2.1. Model survey3.2.2. Sum rules3.2.3. Cabibbo haze in lepton mixing3.3. Lepton-flavour violation3.4. Cosmology3.4.1. Neutrinos and large-scale structure3.4.2.Leptogenesis3.4.3.Neutrinos and inflation4. Effects of new physics beyond the StandardNeutrino model4.1. Sterile neutrinos4.1.1. Theoretical issues4.1.2.Phenomenologyoflightsterileneutrinos 584.1.3.Signatures of heavy sterile neutrinos4.1.4. Sterile neutrinos and cosmology andastrophysics4.1.5.The LSND challenge4.2. Mass varying neutrinos4.3. CPT and Lorentz-invariance violation4.3.1.Direct bounds on CPTV4.3.2. CPTV/LIV effect on conversionprobability4.3.3. Future prospects4.4. Leptonic unitarity triangle and CP violation4.4.1. Properties of the leptonic triangles4.4.2. Leptonic triangles and coherence ofneutrino states4.4.3. The unitarity triangle and oscillationexperiments4.4.4.Leptonic unitarity triangle and futureexperiments373742454850505456585858595960666868696969707072735
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et al188.8.131.52.4.6.Beyond three neutrinosConstraints on unitarity7374754.5. Non-standard interactions4.5.1. Non-standard interactions inproduction and detection4.5.2. Non-standard interactions inpropagation4.5.3. Constraints from non-oscillationneutrino experiments4.5.4. Oscillation experiments as probes ofthe NSI4.5.5.The role of MINOS4.5.6.Complementarity of long and shortbaseline experiments5. Performance of proposed future long-baselineneutrino oscillation facilities5.1. Introduction5.1.1. Definition of observables5.2. The physics potential of super-beams5.2.1. The super-beam concept5.2.2.T2K and T2HK5.2.3. The SPL5.2.4.NOνA5.2.5. Wide-band super-beam5.2.6.Physics at a super-beam facility5.2.7.The waterˇCerenkov detector5.2.8. Backgrounds and efficiencies5.2.9. The super-beam performance5.2.10. The θ13discovery potential5.2.11. CP-violation discovery potential5.2.12. Maximal θ23exclusion potential5.2.13. Sensitivity to the atmosphericparameters5.2.14. Sensitivitiestothemasshierarchyandthe θ23octant5.2.15. Combination with atmosphericneutrino measurements5.2.16. Super-beamassociatedwithabeta-beam1005.2.17. Super-beam associated with theNeutrino Factory5.3. The physics potential of beta-beam facilities5.3.1. Beta-beam setups5.3.2. The low-energy beta-beam: LEββ5.3.3. High-energy beta-beams: HEββ5.3.4. Ion production and ν fluxes5.3.5.Detector technology5.3.6. WaterˇCerenkov5.3.7.NOνA-like detector5.3.8. Atmospheric backgrounds5.3.9. Analysis of performance andoptimization5.3.10. Sensitivity to θ135.3.11. Sensitivity to CP violation5.3.12. Sensitivity to the discrete ambiguities5.3.13. Measurement of θ13and δ5.3.14. Towards an optimal beta-beam setup5.3.15. Combination with atmospheric data5.3.16. An associated super-beam76798485899092929294949495959596969697979899991001001011021031031031031041051051061061071071071081081081105.3.17. Combination of different ions5.3.18. Higher γ?5.3.19. Higher fluxes?5.3.20. Monocromatic e-capture beams5.4. Optimization and physics potential of aNeutrino Factory oscillation experiment5.4.1. The Neutrino Factory setup5.4.2. Physics potential of the golden channel 1175.4.3.Solving degeneracies5.4.4.The optimal Neutrino Factory5.4.5.Low-energy Neutrino Factory5.5. Comparisons6. The potential of other alternatives6.1. Solar- and reactor-neutrino experiments6.1.1. The Generic pp experiment6.1.2.The SK-Gd reactor experiment6.1.3. The SPMIN reactor experiment6.2. Atmospheric-neutrino experiments6.2.1.Is the mixing angle θ23maximal?6.2.2.Resolving the θ23octant ambiguity6.2.3.Resolving theneutrino-mass hierarchy6.3. Neutrino mass hierarchy from future0νββ experiments6.4. Astrophysical methods of determining themixing parameters6.4.1. General remarks about astrophysicalneutrinos6.4.2. Unstable neutrinos arriving fromcosmic distances6.4.3.Stable neutrinos and loss of coherence 1466.4.4.Summary7. Muon physics7.1. Introduction7.2. The magnetic and electric-dipole moments ofthe muon7.3. Search for muon-number violation7.3.1. Theoretical considerations7.3.2.Model-independent analysis of raremuon processes7.4. Experimental prospects7.4.1.µ → eγ7.4.2.µ+→ e+e+e−7.4.3.µ → e conversion7.4.4. Muonium–anti-muonium conversion7.5. Normal muon decay7.5.1.Theoretical background7.5.2.Muon-lifetime measurements7.5.3.Precision measurement of the Michelparameters7.5.4. Experimental prospects7.6. Muon-physics conclusionsAcknowledgmentsAppendix A. Origin of the ISS and its CommitteesAppendix A.1. OriginAppendix A.2. CommitteeReferences110111111111112114124131133134136136136136137138139140ambiguity in the1411421441441451471471471481511511511521531551561581601601611611621621631631631641646
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Rep. Prog. Phys. 72 (2009) 000000 A Bandyopadhyay et al1. Introduction1.1. Neutrino in a nutshellElusive, mysterious, yet abundant. Neutrinos are elementaryparticles, just like the electrons in our bodies. Neutrinos are soelusive that we do not feel ten trillions of them going throughour body every second. They were discovered 50 years ago,butstillposemanymysteries,defyingoureffortstounderstandthem due to their elusiveness. Yet neutrinos are the mostnumerous matter particles in the universe; there are about abillion neutrinos for every single atom.Slowly we began to appreciate the important roles thatneutrinos have played in shaping the universe as we see today.We already know that stars would not burn without neutrinos.Neutrinos played an important role in producing the variouschemical elements that we need for daily life. Given that we(atoms) are completely outnumbered by neutrinos, it is quitecertain that they played even more important roles.There was a major surprise 8 years ago when wediscovered that neutrinos have a tiny, but non-zero, mass quiteagainst the expectations of our best theory. This discoveryopened up new important roles for neutrinos. We are all of asudden grappling with new exciting questions about neutrinosthat may lead to revolutionary understandings on how theuniverse came to be.Because they have mass, neutrinos may have played animportantroleinshapingthegalaxies,andeventuallystarsandplanets. Neutrinos may actually be their own anti-particles;this may be the reason why the Universe did not end up emptybut has atoms in it. Neutrinos seem to be telling us profoundfacts about the way matter and forces are unified, and how thethree types of neutrino are related to each other; we have yetto decipher their message. In addition, neutrinos may actuallybe the reason why the universe exists at all.We are only beginning to understand neutrinos and theirrolesinhowtheuniverseworks. Itwilltakemanyexperimentalapproaches to get the full picture.discussed here will most likely be an essential component ofthis programme.A Neutrino Factory1.2. Neutrino physics as part of the high-energy physicsprogrammeThepresentisaveryinterestingtimeinthefieldoffundamentalphysics: over the past four decades, an impressive theoreticalframework, the Standard Model, has been established. TheStandard Model is capable of explaining how nature worksat the smallest, experimentally accessible distance scales;yet a handful of phenomena seem decisively to elude anexplanation within the Standard Model and are therefore cluesto a more fundamental understanding. These observationsprovide the only clues we have that our understanding offundamental physics is incomplete. The experimental andtheoreticalpursuitofthesecluesdrivesthehigh-energyphysicsprogramme and is likely to guide the bulk of the researchin this area over the coming decades.section, the forces currently driving research in fundamentalphysics are discussed and the possible interplay between theIn this brief sub-component parts of the research programme are investigated,the objective being to establish the context within whichthe future experimental neutrino-physics programme must bedeveloped.Non-zero neutrino masses cannot be explained by theStandard Model. To allow for massive neutrinos, the StandardModel must be modified qualitatively.distinct ways in which the Standard Model can be modified toaccommodate neutrino mass, some of which will be discussedin detail in the next section.knowledge of the properties of the neutrino property does notallow us to choose a particular 'new Standard Model' over allthe others. We do not know, for example, whether neutrinomasses are to be interpreted as evidence of new, very light,fermionic degrees of freedom (as is the case if the neutrinosareDiracfermions),new,veryheavy,degreesoffreedom(asisthe case if the canonical see-saw mechanism is responsible fortinyMajorananeutrinomasses)orwhetheramorecomplicatedelectroweak-symmetry-breaking sector is required. To makeprogress,itisimperativethatnewprobesofneutrinopropertiesbe vigorously developed. This is the main driving force of allexperimental endeavours discussed in this study.According to the Standard Model, the Lagrangian ofnature is invariant under an SU(3)c× SU(2)L× U(1)Ylocalsymmetry, but the quantum numbers of the vacuum are suchthatthisgaugesymmetryisspontaneouslybrokentoSU(3)c×U(1)EM. The physics responsible for this electroweak-symmetry breaking is not known.states that electroweak symmetry breaking arises due to thedynamicsofascalarfield—theHiggsfield. WhiletheStandardModel explanation for this phenomenon is in (reasonable)agreement with precision electroweak measurements, thedefinitive prediction—the existence of a new, fundamentalscalar boson, the Higgs boson—has yet to be confirmedexperimentally.Evenifthestandardmechanismofelectroweaksymmetrybreaking is realized in nature, our theoretical understanding ofparticle physics strongly hints at the possibility that there aremore degrees of freedom at or slightly above the electroweak-symmetry-breaking scale (around 250GeV). Furthermore, itis widely anticipated that these new degrees of freedom willserve as evidence of new organizing principles; examples ofsuch principles include supersymmetry and the existence ofnew dimensions of space.Thepursuitofthemechanismresponsibleforelectroweaksymmetry breaking is the driving force behind the currentandthefuturehigh-energy-colliderphysicsprogramme,whichaims at exploring the high-energy frontier.future, the large hadron collider (LHC) is expected to supplantthe ongoing Tevatron collider as the highest energy particleaccelerator in the world. It is widely expected that theLHC will reveal the mechanism of electroweak symmetrybreaking and provide evidence of new heavy degrees offreedom. Anticipating the potential findings of the LHC-basedexperiments,thecolliderphysicscommunityiscurrentlyplanningahigh-intensity,high-precision,high-energyelectroncollider—the International Linear Collider (ILC). The ILCshould be able to study in detail the electroweak-symmetryThere are severalOur current experimentalThe Standard ModelIn the near7
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et albreaking sector and reveal the properties of the new physics atthe electroweak scale.Finally, several very different but equally impressivemeasurements of the mass-energy budget of the Universe haverevealed beyond reasonable doubt the existence of what isreferredtoas'darkmatter'. Afterseveralyearsofobservation,it is now clear that the Standard Model does not contain thedegreesoffreedomnecessarytoexplainthedarkmatter. Otherthanitsgravitationalproperties,verylittleisknownaboutdarkmatter. It could consist of weakly interacting fundamentalparticles, but it may also consist of very heavy, very weaklyinteracting states or more exotic objects.searches for dark matter are currently among the highestpriorities of the fundamental physics research programme.Experiments that are sensitive to dark matter vary from direct-detection experiments, to neutrino telescopes, to gamma-rayobservatories. The hope is that the pursuit of the dark-matterclue will not only reveal the existence of a new form ofmatter but will also provide other clues that will allow a moresatisfying understanding of the composition of the universeand its behaviour in the first instants after the Big Bang to bedeveloped.Ontopofthedark-matterproblem, wearenowfacedwitha seemingly deeper puzzle—the existence of dark energy. Wearestillfarfromproperlydecodingwhatthispuzzlemeans,anditisnotclearhowprogresswillbemadetowardsresolvingthismost mysterious issue. New experiments are being devised tostudy in more detail the properties of dark energy. The resultsof these experiments may play a large role in modifying ourpicture of how nature works at its most fundamental level.The different probes discussed above not only addressdifferent clues regarding new fundamental physics, but alsocomplete and complement one-another.synergy among the different experiments cannot be overemphasized.Consider the following examples of suchsynergies:ExperimentalThe amount of1. While new physics at the electroweak scale is usually beststudiedusingahigh-energycollider,thereareseveralnew-physics phenomena that will only manifest themselves inneutrino experiments, including new light, very-weakly-coupled degrees of freedom that could be related to darkmatter or dark energy;2. The knowledge of neutrino properties is essential forthe understanding of certain dark-matter searches (forexample those performed using neutrino telescopes);3. A high-energy collider may provide the only means ofstudyinginanydetailthepropertyofdarkmatterparticlesand4. A proper understanding of the origin of neutrino masscan only be obtained after the mechanism of electroweak-symmetry breaking is properly understood.It is important to bear in mind that we do not knowwhat the next set of clues will be, or where they will comefrom. It may turn out, for example, that neutrino experimentsprovide our only handle on grand unification and other typesof very high energy physics, or that astrophysical searches forthe properties of dark energy will reveal a direct window onquantum gravity. Or it may turn out that collider experimentswillbeabletostudydirectlystring-theoreticaleffects(thismaybe the case if there really are large extra dimensions). Only acomprehensive pursuit of the questions that we can formulatetoday will allow us to reach the next stage in understandingfundamentalphysics—andaskanewsetofmorefundamental,deeper questions tomorrow. In this sense, we perceive thephysicsdiscussedheretobeonequalfootingwithotherstudiesof fundamental importance to our field, including the directsearches for dark matter, satellite missions that will measurethe acceleration of the universe or collider experiments at theenergy frontier. These are all different, complementary waysof addressing the different questions that we cannot answergiven our current understanding of fundamental physics.1.3. Implications and opportunitiesFundamentalfermions,areclassifiedinthreegenerations,eachgeneration containing six quarks (two flavours, three colours)and two leptons. The measured properties of these particlesexhibit a clear 'horizontal' hierarchy in which the mass offermionscarryingthesameStandardModelquantumnumbersincreases with generation number. Within a generation, thefermionpropertiesalsoexhibit'vertical'patterns,forexample,the sum of the electric charge of the members of a particulargeneration is zero. The quarks come in three colour varieties,the source of the strong force. Under the weak force, both thequarksandtheleptonswithinaparticulargenerationtransformas a doublet. In contrast to the general expectation, the mixingangles among lepton flavours have turned out to be differentto the quark-mixing angles. Many of the properties of theneutrino are unique, not shared by the other fundamentalfermions. Firstly, it has neither colour nor electric charge;hence it is the only fundamental fermion that feels solely theweak force in addition to the gravitational force. This factbecomes important when cosmological impact of the neutrinois discussed. Secondly, neutrino masses are tiny comparedwith the masses of all other fundamental fermions. Thirdly,the neutrino could be a Majorana particle; a fermion whichcannot be distinguished from its own antiparticle66.The physics of flavour seeks to provide an explanation ofthese observed patterns. The vertical patterns noted above canbeexplainedin'GrandUnifiedTheories'(GUTs)inwhichthefermions are assigned to representations of a large symmetrygroup such as SO(10). The horizontal, or family patterns,can be explained by assuming a family symmetry such asSU(3)family. Some models that incorporate GUT and familysymmetries with supersymmetric extensions come within therealm of string theories that incorporate extra dimensions.Understandingthesymmetrystructureseemstobeapromisingstrategy to arrive at a description of the physics of flavour.Neutrino oscillations are a phenomenon in which theneutrino changes flavour as it propagates. It was predicted byPontecorvo[2,3]andMakietal [4]andthefirstclearevidencefor neutrino oscillations was presented by Super-Kamiokandein 1998 in observations of the zenith-angle distributions of66The observation of double-beta-decay processes in which no neutrino isproduced would imply that the neutrino is its own antiparticle [1].8
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et alFigure 1. The ratio of the measured to the predicted neutrino flux is plotted as a function of L/E. The anti-electron-neutrino contribution tothe reactor neutrino flux measured by the KamLAND collaboration [8] is shown. (Figure courtesy of K Inoue).atmospheric neutrinos [5].dates back as early as 1970, when the Homestake groupdetected a deficit in the solar-neutrino flux compared withthat predicted by the Standard Solar Model [6]. The long-standing 'solar neutrino puzzle' was finally proved to be aresultofoscillationsbySNOin2001[7]. Thefirstobservationof neutrino oscillations from terrestrial neutrino sources wasobtained by KamLAND by measuring the energy spectrumof neutrinos produced in nuclear reactors [8].of the KamLAND measurement, shown in figure 1, exhibitsthe expected oscillatory behaviour and constitutes compellingevidence for neutrino oscillations [9].Neutrinooscillationsoccurbecauseofflavourmixingandthe tiny, but different, masses of the neutrinos.saw mechanism, the most attractive and promising schemeto explain the tiny mass, requires the presence of very heavyMajorana neutrinos. In such models, neutrino oscillations area consequence of the physics which pertains at an extremelylarge energy scale.See-saw models are able to explainthe striking difference between the quark- and lepton-mixingangles in a natural way. If the heavy Majorana neutrinois abundant in the early Universe and decays preferentiallyinto matter leptons in a CP violating process, then the leptonasymmetry would be converted into a baryon asymmetry asplit second later during the electroweak era. This process isreferred to as 'leptogenesis' and is a primary theory to explainour matter universe. The neutrino is the most abundant of thematter fermions in the Universe; with a billion neutrinos foreach of the other known matter particles, only the ubiquitousphoton is more abundant. Hence, the tiny neutrino mass couldcontribute a non-negligible fraction of the dark matter and isknowntoplayanimportantroleintheformationoflarge-scalestructure in the Universe.Because of its direct connection with phenomena atenergies never seen since the Big Bang, the precisedetermination of the masses and mixing angles of the threefamilies of neutrino is a unique window onto these earlytimes and provides a path to the possible unification of allThe first indication, however,The resultThe see-forces. Measurements of neutrino oscillations can be used todetermine the three mixing angles and the CP-violating phaseof the lepton-mixing matrix (the PMNS, Pontecorvo–Maki–Nakagawa–Sakata matrix) and two mass-squared differences.Examining neutrino oscillations is a most direct way todistinguishbetweenthevariouspossibletheoriesofthephysicsof flavour and to understand the origin of neutrino mass. It isalso a logical place to seek for the origin of the CP violation.Taking a different perspective, ever since Pauli's 1931prediction, the unveiling of the properties of the neutrino hasalways heralded a new epoch in the history of elementaryparticle physics. Including the neutrino as a player of betadecay, Fermi formulated the first successful theory of weakinteractions. The absence of right-handed neutrinos hasmanifested itself as the 'V–A' structure of the weak interactionand the pursuit of its origin led to the discovery of thechiral gauge theory which forms the foundation of modernparticle theories. The realization of intense neutrino beamsimmediately resulted in the discovery of the neutral current,establishing the unification of the electroweak interactions.The ability of neutrino interactions to distinguish flavour andhandedness has been extensively utilized in deep inelasticinteractions to clarify the structure of the nucleon andto establish the asymptotic freedom of QCD. The recentdiscoveryofneutrinooscillationscouldberegardedasanotherepoch-making observation. So far it is the only experimentalevidence for, and a vital clue to, the physics beyond theStandard Model. Both the mysteries, and the brilliant record,oftheneutrinocanbeattributedtoitsuniqueandcharacteristicinsensitivity to both the strong and the electromagnetic forces.Thereareamplereasonstobelievethatthisassetremainsvalidin uncovering the veils that surround the neutrino. Neutrinofacilities to pursue oscillation phenomena are complementaryto high-energy colliders and are competitive candidates for thenext world-class facilities for particle physics.9
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et al1.4. Precision measurements and sensitive searchesExperimentally, there are several different approaches toelucidate the properties of the neutrino. In this report weconcentratemainlyonaccelerator-basedfacilitiesilluminatingmassive, underground detectors. Other complementary meansare also taken into account and are described in section 6.Among them, reactor-based oscillation experiments may playa crucial role in untangling the degeneracies inherent inoscillation measurements. Other techniques include double-beta decay, a unique tool to test the Majorana nature of theneutrino [1]. Massive, underground detectors, while servingas a far detector for the oscillation experiments, also have animportant role in their own right as telescopes for neutrinoastronomy and as a possible window on grand unified theoriesby way of searching for proton decay.Theories that purport to explain neutrino oscillations haveconsequences for the properties of the charged leptons, suchas flavour-changing process in lepton decay or lepton-inducedreactions. Considering that very intense muon beams will beavailable as a by-product of the Neutrino Factory, it is naturalto include muon physics as an indispensable ingredient of thestudy. Section7discussesindetailtheopportunitiesthathigh-statistics studies of the properties of the muon have to offer.The present generation of neutrino-oscillation experi-ments [10–12], reviewed in section 2, are designed to measurethe smallest neutrino-mixing parameter if it is not 'too small'.Theyutilizeintensepionbeams(super-beams)togenerateneu-trinos. They are designed to seek and measure the third mix-ing angle θ13of the PMNS matrix, but will have little or nosensitivity to matter–antimatter symmetry violation. Severalneutrino sources, including second-generation super-beams,beta-beams and the Neutrino Factory have been envisaged toreach high sensitivity and redundancy well beyond that whichcan be achieved in the presently approved neutrino-oscillationprogramme. Section 5 reviews the detailed performance ofeach of these classes of facility and presents quantitative com-parisons of the physics potential. Their essential features arebriefly introduced below.The super-beam is a natural extension of the conventionalneutrino beam and the current and approved experiments aremostly of this type [13–23]. The neutrino beam is producedthrough pion and kaon decay and hence these facilitiesprovide beams in which νµ and ¯ νµ dominate the neutrinoflux. However, these beams also contain νe(¯ νe) from kaonand muon decay which constitute an irreducible backgroundfor the oscillation signal νµ(¯ νµ) → νe(¯ νe).the selection of samples of νe(¯ νe) is prone to neutral currentcontamination. The principal source of systematic uncertaintyarises from the fact that the spectral shape of the pions andkaons is not well known. In the second-generation super-beam experiments, the emphasis is on large detector mass,i.e. the collection of large data samples, and on muon andelectron particle identification. This detector solution mostoften adopted for second-generation super-beam experimentsis the megaton-scale water Cherenkov counter. Liquid-argondetectors or large volume scintillator detectors have also beenconsidered.In addition,The beta-beam [24], in which electron-neutrinos or (anti-neutrinos) are produced from the decay of stored radio-activeionbeams,providesessentiallybackground-freepure'golden-channel' (νe → νµ), i.e. 'the appearance of wrong-signmuons'. Unlike the Neutrino Factory, the beta-beam does notneed a magnetized detector, because there is no contaminationfrom anti-neutrinos. This allows the beta-beam to use a verymassive detector just as the second-generation super-beamdoes [25,26]. Simultaneous operation of the beta-beam andthe second-generation super-beam has also been considered[27]. The disadvantage of the beta-beam is lack of the 'silverchannel', the νe→ ντ, transition for most of the case studied.The Neutrino Factory [28,29], an intense high-energyneutrino source derived from the decay of a stored-muonbeam, has access to all channels of neutrino-flavour transitionincluding the golden channel.induced muon–neutrino events requires that the detector bemagnetized. This leads most naturally to the magnetized- ironcalorimeter design. Another unique feature of the NeutrinoFactory is the possibility to observe the silver channel. Thiscan be achieved using either emulsion based detectors or amagnetized liquid-argon time-projection chamber.Studies [30–35] so far have shown that the NeutrinoFactory gives the best performance over virtually all ofthe parameter space; its time scale and cost remain,however, important question marks. Super-beams have manycomponents in common with the Neutrino Factory. A beta-beam may be competitive with the Neutrino Factory in someparameter space, but, being relatively new in this field, needsfurther study to fully explore its capability.Thereisanimportantissuecommontoallthefacilitiesthatmustbeborneinmind. Atypicaloscillationexperiment,tryingto determine the small mixing angle θ13and the CP-violatingphase δ, generally suffers from the correlation/degeneracyproblem, described in detail in section 2.4. These correlationsand degeneracies reduce the sensitivity typically by one orderof magnitude over that given by the statistical and systematicuncertainties. This happens because a canonical oscillationexperiment measures only two transition rates, P(να → νβ)and P(¯ να → ¯ νβ) and the expression for these probabilitiesis a quadratic function of two unknown variables, sin2θ13and sinδ. Given two measured values at fixed energy, E,and baseline, L, the solution of the equations has an extra,fake, (θ13,δ) solution which is referred to as the intrinsicdegeneracy. Our ignorance of the sign of ?m2degeneracy), andtheindistinguishabilityofθ23fromπ/2−θ23(theoctantdegeneracy)resultsinatotaleight-folddegeneracy.The problem can be resolved in one of three ways:However, to reject beam-23(the sign1. To place a second detector at different values of L/E;2. To add a different channel (or to combine data froma complementary source, for example from a reactorexperiment) and3. To use an improved detector with lower threshold andbetter energy resolution.Method (3) may be regarded as a variant of (1) from thephysics point of view because it is essentially equivalent towidening the energy spectrum. This is the reason why the10
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Rep. Prog. Phys. 72 (2009) 000000 A Bandyopadhyay et alconsideration of synergy among the proposed, as well as thecurrent experiments, is particularly important in oscillationphysics. More often than not, the combination of experimentsof different design can achieve a sensitivity that far exceedswhat a mere statistical gain would suggest.NOvA [16] expects to enhance its sensitivity by combiningwithaproposedreactorexperimentandanupgradedversionofNOvA [17,18] proposes to put a second detector at a differentoff-axis angle (i.e. energy). T2KK [19,20], a variation ofT2HK [13], proposes to split their megaton water detectorin two and place one in Korea, a remedy using two differentbaselines (L = 295km and ?1050km). The on-axis WBB[23,36,37], averylong-baselinewide-bandbeamfromFNALor BNL to Henderson or Homestake mine in the US, on theother hand, takes advantage of its wide spectrum to resolvethe problem. It has also been shown that the combinationof atmospheric-neutrino data with T2HK [38] or a low-energy beta-beam [27] is extremely helpful in resolving thedegeneracies related to the mass hierarchy and the octantdegeneracy. These examples illustrate the importance ofworkingtowardstheidentificationofanoptimumcombinationof the various facilities.For all detector concepts, there are important questionsconcerning cost, feasibility and time scales. In addition, thereare design optimizations to be made, e.g. between energy andangle resolution, optimum baseline length and detector mass.The study of detector concepts for the near detector stationswill be an important aspect of the neutrino physics because ofits access to many reactions complementary to the oscillationprocess.For the neutrino-physics community to arrive at aconsensusonthebestpossibleneutrino-oscillationprogrammeto follow the present generation of experiments requiresa detailed evaluation of the performance and cost of thevarious options and of the timescale on which each can beimplemented. Further R&D programmes into the acceleratorsystems and the neutrino detectors must be carried out.For instance,1.5. What the study tried to achieveTheroleofthePhysicsGroupoftheISSstudywastoestablishthe strong physics case for the various proposed facilities andto find the optimum parameters of the accelerator facility anddetector systems from the physics point of view. The firstobjective of this report, therefore, is to try to identify the bigquestions of neutrino physics such as the origin of neutrinomass, the role of the neutrino in the birth of the universe, whatthe properties of the neutrino can tell us about the unificationof matter and force. These questions lay down the basis formaking the physics case for the various neutrino facilities.Since it is not (yet) possible to answer these questions ingeneral, studies have concentrated on more specific issues thatmay lead to answers to the big questions. A class of directlytestablepredictionsisaffordedbythefactthatGUTandfamilysymmetries result in relationships between the quark- andlepton-mixing parameters; such relationships can be cast inthe form of sum rules.Thesecondobjectivewastolookforpossiblecluesofnewphysics in a 'bottom-up' approach. For this purpose, we haveevaluated the degree to which the various facilities, alone orin combination, can distinguish between the various modelsof neutrino mixing and determined optimum parameter setsfor these investigations. One example is to search for theexistenceofasterileneutrino. Althoughtheanomalypresentedby LSND [39] was not confirmed by MiniBooNE [40], thequestionisimportantenoughtobepursuedfurther. Thesecondexample is the unitary triangle: while the CKM matrix in thequarksectorisconstrainedtobeunitaryintheStandardModel,thePMNSmatrixoriginatesfromphysicsbeyondtheStandardModeland,insee-sawmodels,maynotbeexactlyunitary. Thethird example is the existence of flavour-changing interactionsthat might appear at the production point, in the oscillationstage or at the detection point. Possible strong correlationsbetween lepton-flavour violation and neutrino oscillationswere also discussed. Other approaches to the determinationof the three-flavour parameters (i.e. non-accelerator basedmeasurements) were also considered.possibility of a new long-baseline reactor experiment and theloading of the water in the Super-Kamiokande detector withgadolinium to improve the solar-neutrino parameters, or anlarge, underground, magnetized-iron detector to improve theatmospheric-neutrinoparametersandtotestfordeviationfrommaximal mixing and determine the octant degeneracy werealso discussed.Thethird, andthekey, objectiveofthisreportistopresentthe first detailed comparison of the performance of the variousfacilities. Utilizing realistic specifications, we have estimatedlikely performances, tried to find an optimum combination offacilities, baselinesandneutrinoenergies, andtocomeupwithsome staging scenarios.Although past studies have shown that the NeutrinoFactory can be considered as an excellent, and perhaps asan ultimate, facility, many questions remain open.instance, the performance of the Neutrino Factory at largeθ13(sin22θ13 ? 10−2) where most super-beam experimentswork is only now being studied in detail [41]. A questionthat must therefore be asked is: 'Can the Neutrino Factoryremain competitive if θ13turns out to be large?'. Anotherconcern is the cost of the accelerator facility and the detectorsystems. One estimate [32] in previous studies gives a totalcost of 1500 M$ + 400 M$ × E/20(GeV). Therefore, thesecond question is: 'What is the minimum energy that willdeliver the physics?'. The Neutrino Factory operates atenergies considerably higher than the first oscillation peak(Emax/GeV = L/564km). Thecanonicaloperatingconditionin past studies has been to use a parent muon beam of 50GeVand a 50kton magnetized-iron detector at a distance of 3000–4000km [42]. Because of its operation at high energy witha single detector, it suffers from the degeneracy problem atintermediate values of θ13(10−3? sin22θ13? 10−2). It hasbeen shown that remedies exist through the addition of eithera second detector at the 'magic' baseline (L ? 7500km) [43]or the silver channel [44]. Both of these solutions require theseconddetector. So,thethirdquestionis'Canasingle-detectorconfiguration with improved performance do any better, and iftwodetectorsareunavoidable,whichcombinationisthebest?'.In order to answer those questions, an extensive investigationFor example, theFor11
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et alin the parameter space (Eµ− L) was carried out.various combinations have been compared with the intentionto identify both a conservative option and an improved set ofdetector configurations with possible staging.Direct, quantitative comparison of the various facilitiesis a highlight of the study. The GLoBES package [45,46]was used. Other codes, Valencia and Madrid, showed goodagreement with GLoBES in a test using a single referenceinput. A realistic set of detector specifications and aprecise normalization of neutrino flux and cross-sections wereprepared. The comparisons are made for three performanceindicators only (sin22θ13, the sign of mass hierarchy andthe CP violation phase δ). If other physics topics, such ase,µ−τ flavouranomalysearches,areemphasized,therelativeimportance may be different.The final contribution to this report reviews the muonphysics that can be performed with the intense muon beamsthat will be available at the Neutrino Factory. The study ofrare processes in muon decay and muon-electron and muon-nucleon scattering is complementary to precision studies ofneutrino oscillations; often sensitive to the same underlyingphysics. The complementarity and the potential of a muon-physics programme at the Neutrino Factory is investigated. Itwillbeimportantinthecomingyearstoestablishquantitativelythequalitativesynergybetweenmuonphysicsandthestudyofneutrino oscillations.This report is organized as follows. First, in section 2,we give a review of the present generation of experiments,state what is needed to complete the picture and explainthe degeneracy problem. Next we expand upon the physicsmotivationfortheneutrino-oscillationprogrammeinsections3and4; section3containsa'big-picture'descriptionofneutrinophysics addressing such questions as the origin of neutrinomass, extra dimensions, flavour symmetry and the role of theneutrino in unification and in cosmology, while section 4 takesa phenomenological approach to consider how measurementsof neutrino properties may provide clues to new physicsthrough studies such as the search for sterile neutrinos, theinvestigation of the leptonic unitary triangle and the searchfor non-standard interactions in the oscillation experiments.Section 5 deals with the physics potential of the proposedfacilities: the super-beam; the beta-beam and the NeutrinoFactory. Direct comparison of various facilities is given here.Alternativeexperimentswhichcancomplementtheoscillationexperiments are described in section 6. The final section 7 isdevoted to muon physics.Then,2. The standard neutrino model2.1. IntroductionThe 'standard neutrino-mixing model' emerged as a resultof the remarkable progress made in the past decade in thestudies of neutrino oscillations. The experiments with solar,atmospheric and reactor neutrinos [5–7,47–55] have providedcompelling evidence for the existence of neutrino oscillationsdriven by non-zero neutrino masses and neutrino mixing.Evidence for neutrino oscillations were also obtained in thelong-baseline accelerator-neutrino experiments K2K [56,57]and MINOS [11].We recall that the idea of neutrino mixing and neutrinooscillations was formulated in [2–4].1967 [58] that the existence of νeoscillations would causea 'disappearance' of solar νeon the way to the Earth. Thehypothesis of solar-νeoscillations, which (in one variety oranother) were considered from ∼1970 on as the most naturalexplanation of the observed [6,47–50] solar-neutrino, νe,deficit (see, e.g. [59–64]), has been convincingly confirmed inthemeasurementofthesolar-neutrinofluxthroughtheneutral-current (NC) reaction on deuterium by the SNO experiment[7,52–54], and by the first results of the KamLANDexperiment [55]. The combined analysis of the solar-neutrinodata obtained by the Homestake, SAGE, GALLEX/GNO,Super-Kamiokande, and the SNO experiments, and of theKamLAND reactor ¯ νe data [55], established large mixingangle (LMA), MSW oscillations [60,61] as the dominantmechanism giving rise to the observed solar-νedeficit (see,e.g. [65]). The Kamiokande experiment [47] provided the firstevidence for oscillations of atmospheric neutrinos, νµand ¯ νµ,while the data from the Super-Kamiokande experiment madethe case for atmospheric-neutrino oscillations convincing[5]. Indications for ν-oscillations were also reported by theLSND collaboration [39] but are disfavoured by the recentMiniBooNE measurement [40].Compelling confirmation of oscillations in (νµ, ¯ νµ),and reactor, ¯ νewas provided by L/E-dependence observedby Super-Kamiokande [9] and by the spectral distortionobserved by the KamLAND and K2K experiments [8,57].For the first time the data exhibit directly the effects ofthe oscillatory dependence on L/E and E characteristic ofneutrino-oscillations in vacuum [66]. As a result of thesedevelopments, the oscillations of solar νe, atmospheric νµand¯ νµ, accelerator νµ(at L ∼ 250km and L ∼ 730km) andreactor ¯ νe(at L ∼ 180km), driven by non-zero ν-masses andν-mixing, can be considered as practically established.All existing ν-oscillation data, except the data of LSNDexperiment [39], can be described assuming three-neutrinomixing in vacuum. Let us recall that in the LSND experimentindications for ¯ νµ → ¯ νe oscillations with (?m2)LSND ?1eV2were obtained.The minimal four-neutrino-mixingscheme which could incorporate the LSND indications for ¯ νµoscillations is disfavoured by the existing, long-baseline data[67]andbytherecentMiniBooNEdata[40]. Theν-oscillationexplanation of the LSND results is possible assuming five-neutrino mixing [68].The three-neutrino mixing scheme will be referred to inwhat follows as the 'Standard Neutrino Model' (SνM). It isthe minimal neutrino-mixing model which can account for theoscillations of solar (νe), atmospheric (νµand ¯ νµ), reactor (¯ νe)and accelerator (νµ) neutrinos. In the SνM, the (left-handed)fields of the flavour neutrinos νe, νµand ντin the expressionfor the weak charged-lepton current are linear combinationsof fields of three neutrinos νj, j = 1,2,3, having definite12It was predicted in
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Rep. Prog. Phys. 72 (2009) 000000mass mj:A Bandyopadhyay et alνeLνµLντL= UPMNSν1Lν2Lν3L=Ue1Ue2Ue3Uµ1Uµ2Uµ3Uτ1Uτ2Uτ3ν1Lν2Lν3L,(1)where UPMNS is the Pontecorvo–Maki–Nakagawa–Sakata(PMNS) neutrino-mixing matrix [2–4], UPMNS ≡ U. ThePMNSmixingmatrixcanbeparametrizedbythreeangles,and,depending on whether the massive neutrinos νjare Dirac orMajoranaparticles,byoneorthreeCP-violation(CPV)phases[69–72]. In the standard parametrization (see, e.g. [73]),UPMNShas the form:UPMNS=×diag(1,eiα/2,eiβ/2),where cij = cosθij, sij = sinθij, the angles θij = [0,π/2],δ = [0,2π] is the Dirac CPV phase and α,β are twoMajorana CP-violation phases [69–72].?m2responsible for the solar-neutrino oscillations. In this case|?m2squared difference driving the dominant atmospheric-neutrinooscillations, while θ12 = θ?and θ23 = θAare the solar andatmospheric neutrino-mixing angles, respectively. The angleθ13is the so-called 'CHOOZ mixing angle'—it is constrainedby the data from the CHOOZ and Palo Verde experiments[74,75].Let us recall that the properties of Majorana particlesare very different from those of Dirac particles. A massiveMajorana neutrino χk with mass mk > 0 can be described(in local quantum field theory) by a 4-component, complexspin-1/2 field, χk(x), which satisfies the Majorana condition:c12c13s12c13s13e−iδ−s12c23− c12s23s13s12s23− c12c23s13eiδ−c12s23− s12c23s13eiδc23c13c12c23− s12s23s13eiδs23c13(2)One can identify?= ?m221> 0 with the neutrino mass squared differenceA| = |?m231|∼= |?m232| ? ?m221is the neutrino mass-C( ¯ χk(x))T= ξkχk(x),where C is the charge conjugation matrix. The Majoranacondition is invariant under proper Lorentz transformations.It reduces by two the number of independent componentsin χk(x).Condition (3) is invariant with respect to U(1) globalgaugetransformationsofthefieldχk(x)carryingaU(1)chargeQ, χk(x) → eiαQχk(x), only if Q = 0. As a result andin contrast to the Dirac fermions: (i) the Majorana particlesχkcannot carry non-zero additive quantum numbers (leptoncharge, etc) and (ii) the Majorana fields χk(x) cannot 'absorb'phases. This is the reason why the PMNS matrix containstwo additional CP-violating phases in the case when themassive neutrinos νkare Majorana fermions [69], νk≡ χk. ItfollowsfromtheabovethattheMajorananeutrinofield,χk(x),describes the two spin states of a spin 1/2, absolutely-neutralparticle, which is identical with its antiparticle, χk ≡ ¯ χk. IfCP-invariance holds, Majorana neutrinos have definite CP-parity, ηCP(χk) = ±i:UCPχk(x)U−1|ξk|2= 1,(3)CP= ηCP(χk)γ0χk(x?),ηCP(χk) = ±i.(4)It follows from the Majorana condition that the currents:¯ χk(x)Oiχk(x) :≡ 0, for Oi= γα; σαβ; σαβγ5. This meansthat Majorana neutrinos cannot have non-zero U(1) chargesand intrinsic magnetic- and electric-dipole moments. Diracfermions can possess non-zero lepton charge and intrinsicmagnetic- and electric-dipole moments67.The existing data allow a determination of ?m2and of |?m2e.g. [77–79] and sections 2.2.1 and 2.2.2). For the best-fitvalues we have ?m2|?m2|?m2not fixed by current data. The present atmospheric-neutrinodata is essentially insensitive to θ13, satisfying the upper limiton sin2θ13 obtained in the CHOOZ experiment [80]. Theprobabilities of survival of solar νeand reactor ¯ νe, relevantfor the interpretation of the solar neutrino, KamLAND andCHOOZ neutrino-oscillation data, depend on θ13in the caseof interest, |?m2?P3ν?, sin2θ12A|, sin22θ23with a relatively good precision (see,?= 8.0 × 10−5eV2, sin2θ12 = 0.30,A| = 2.5 × 10−3eV2, sin22θ23 = 1. Thus, ?m2A|. It should be noted, however, that the sign of ?m2??Ais31| ? ?m221:P3νKL∼= sin4θ13+ cos4θ13CHOOZ∼= 1 − sin22θ13sin2?m2P3ν1 − sin22θ12sin2?m221L4E?,31L4E,?∼= sin4θ13+ cos4θ13P2νwhere P2ν?corresponding to 2-ν oscillations driven by ?m2whichthesolare−numberdensityNeisreplacedbyNecos2θ13[84], P2ν?[81–83] and?(?m221,θ12;Necos2θ13),is the solar νe survival probability [81–83]21and θ12, in= ¯ P2ν?+ P2ν? osc, P2ν? oscbeing an oscillating term¯ P2ν?=12+?12− P??cos2θm212E12cos2θ12,(5)P?=e−2πr0?m2sin2θ12− e−2πr01 − e−2πr0?m22E21?m22E21.(6)Here¯ P2ν'double exponential' jump probability [81–83], r0is the scale-height of the change of Nealong the ν-trajectory in the Sun[81–83,87–89], and θmin the vacuum limit coincides with θ12. In the LMA solutionregion of interest, P2νanalysis of the solar-neutrino, CHOOZ, and KamLAND data,one finds [77–79]: sin2θ13< 0.040 at 99.73% CL.It follows from the results described above that theatmospheric-neutrino mixing is close to maximal, θ23∼= π/4,the solar-neutrino-mixing angle θ12∼= π/3 and the CHOOZangle θ13< π/15. Correspondingly, the pattern of neutrino?is the average probability [81–83,85,86], P?is the12is the mixing angle in matter, which? osc∼= 0 [89]. Performing a combined67Let us add, finally, that Majorana neutrinos have in addition to the standardpropagator (formed by the neutrino field and its Dirac conjugate field), twonon-trivial non-standard (Majorana) propagators. If νj(x) in equation (1)are massive Majorana neutrinos, the process of (ββ)0ν-decay, (A,Z) →(A,Z+2)+e−+e−,forexample,canproceedbyexchangeofvirtualneutrinosνj due to one of these Majorana propagators. For Dirac fermions, the twoanalogousnon-standardpropagatorsareidenticallyequaltozero. Forafurtherdetailed discussion of the properties of Majorana neutrinos (fermions) see,e.g. [62,76].13
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Rep. Prog. Phys. 72 (2009) 000000A Bandyopadhyay et almixing is drastically different from that of the quark mixing.A comprehensive theory of flavour and of neutrino mixingmust be capable of explaining this remarkable difference. Thecurrenttheoreticalideasaboutthepossibleoriginofthepatternof neutrino mixing are reviewed in section 3.As we have seen, the fundamental parameters character-izing the SνM are (i) the three angles θ12, θ23, θ13; (ii) de-pending on the nature of massive neutrinos νj- 1 Dirac (δ), or1Dirac+2Majorana(δ,α,β),CP-violationphasesand(iii)thethreeneutrinomasses,m1,m2,m3. Thismakesnineadditionalparameters in the Standard Model of particle interactions.Itisconvenienttoexpressthetwolargerneutrinomassesinterms of the third mass and the measured ?m2and ?m2neutrino,K2K,andMINOSdatadonotallowonetodeterminethe sign of ?m2This implies that, if we identify ?m2with ?m2?m2correspond to two types of ν-mass spectrum:?= ?m221> 0A. We have remarked earlier that the atmospheric-A.A31(2)in the case of 3-neutrino mixing, one can have31(2)> 0 or ?m231(2)< 0. The two possible signs of ?m2A• Normal ordering: m1< m2< m3, ?m2m2(3)= (m2• Invertedordering68:m3< m1< m2, ?m2m2= (m2Depending on the values of the lightest neutrino mass,min(mj), the neutrino-mass spectrum can also beA= ?m231> 0,1+ ?m221(31))12 andA= ?m223− ?m232< 0,21)3+ ?m223)12, m1= (m23+ ?m212.• Normal(?m2• Inverted hierarchy (IH): m3 ? m1 < m2, with m1,2∼=|?m2• Quasi-degenerate (QD): m1∼= m2∼= m3∼= m0, m2|?m2One of the principal goals of the future studies of neutrinomixing is to determine the basic parameters of the SνM and totest its validity.The possibilities of measuring with high precisionthe basic parameters of SνM ?m2sin22θ23, sin2θ13, of determining sgn(?m2for the effects of CP violation due to the Dirac phaseδ, in neutrino-oscillation experiments, will be discussed indetail below. It is well known that the neutrino-oscillationexperiments are not sensitive to the absolute scale of neutrinomasses. Information on the absolute neutrino-mass scale, oron min(mj), can be derived in3H β-decay experiments andfrom cosmological and astrophysical data (see sections 2.2.4and 184.108.40.206).The most stringent upper bounds on the ¯ νemass and on the sum of neutrino masses will be discussedbriefly in sections 2.2.4 and 3.4.2. These bounds lead to theconclusion that neutrino masses satisfy mj ? 1eV and thusare much smaller than the masses of the charged leptons andquarks. A comprehensive theory of neutrino mixing should behierarchy2 ∼ 0.009eV, m3∼= |?m2(NH):m1? m2?m3,A|m2∼=?)112 ∼ 0.05eV;A|12 ∼ 0.05eV orj?A|, m0? 0.10eV.?, sin2θ? |?m231) and of searchingA|,68In the convention we use (called A), the neutrino masses are not orderedin magnitude according to their index number: ?m2m3< m1< m2. We can also always number the neutrinos with definite massinsuchawaythat[90]m1< m2< m3. Inthisconvention(calledB),wehavein the case of inverted-hierarchy spectrum: ?m2Convention B is used, e.g. in [73,91].31< 0 corresponds to?= ?m232, ?m2A= ?m231.able to explain this enormous difference between the neutrinoand charged-fermion masses. The theoretical aspects of theproblem of neutrino-mass generation and of the smallness ofneutrino masses are reviewed in section 3.1.Neutrino-oscillation experiments are also insensitive tothe nature, Dirac or Majorana, of massive neutrinos and,correspondingly, to the two CP-violating, Majorana phasesin the PMNS matrix [69,92] since the latter do not enter intothe expressions for the probabilities for neutrino oscillations.The only realistic experiments which could verify that themassive neutrinos νj are Majorana particles are, at present,the neutrinoless double-beta ((ββ)0ν-) decay experiments.The physics potential of these experiments is discussed insection 2.2.4. Even if massive neutrinos are proven to beMajoranafermions, measuringtheMajoranaCPphaseswouldbe extremely challenging. It is quite remarkable, however,that the Majorana CP-violating phase(s) in the PMNS matrix,through leptogenesis (see section 3.4.2, may result in thebaryon asymmetry of the Universe [93–95]).The existing data on neutrino oscillation, as we will see,allow a determination of ?m2at 3σ with an uncertainty of approximately ∼12%, ∼24%,∼28% and ∼15%, respectively. These parameters can, andvery likely will, be measured with much higher accuracy inthe future: the indicated 3σ errors in the determination, forinstance, of ?m2and10%,aswillbereviewedbelow. 'Near'futureexperimentswith reactor ¯ νecan improve the current sensitivity to the valueof sin2θ13 by a factor of between 5 and 10. The type ofneutrino-massspectrum,i.e.sgn(?m2studying the oscillations of neutrinos and anti-neutrinos, say,νµ↔ νeand ¯ νµ↔ ¯ νe, in which matter effects are sufficientlylarge. If sin22θ13 ? 0.05 and sin2θ23 ? 0.50, informationon sgn(?m2experiments by investigating the effects of the sub-dominanttransitions νµ(e) → νe(µ)and ¯ νµ(e) → ¯ νe(µ)of atmosphericneutrinos which traverse the Earth [99–101]. For νµ(e)(or¯ νµ(e)) crossing the Earth's core, new types of resonance-like enhancement of the oscillation probabilities may takeplace due to the mantle-core constructive-interference effect(neutrino oscillation length resonance (NOLR)) [102–105].As a consequence of this effect, the corresponding νµ(e)(or ¯ νµ(e)) transition probabilities can be maximal [103–105].For ?m2enhanced, while for ?m2neutrino transitions ¯ νµ(e) → ¯ νe(µ)takes place, which mightallow determination of sgn(?m2It should be emphasized that the CP violation in thelepton sector is one of the most challenging frontiers infuture studies of neutrino mixing. The experimental searchesfor CP violation in neutrino oscillations can help answerfundamental questions about the status of CP-symmetryin the lepton sector at low energy.leptonic-CP violation at low energies will have far-reachingconsequences. It can shed light, in particular, on the possibleorigin of the baryon asymmetry of the Universe.realized recently [93,94], the CP violation necessary for thegeneration of the baryon asymmetry can be due exclusively to?, sin2θ?, |?m2A|, and sin22θ23,?and sin2θ?, can be reduced to [96–98] 4%31),canbedeterminedby31) might be obtained in atmospheric-neutrino31> 0, the neutrino transitions νµ(e) → νe(µ)are31< 0 the enhancement of anti-31).The observation ofAs was14
Page 15
Rep. Prog. Phys. 72 (2009) 000000 A Bandyopadhyay et althe Dirac (and/or Majorana) CP-violating phase in the PMNSmatrix. Thus, there can be a direct relation between low-energy CP violation in the lepton sector, observable, e.g. inneutrino oscillations, and the matter–antimatter asymmetryof the Universe. These results underline the importance ofunderstanding the status of the CP-symmetry in the leptonsector and, correspondingly, of the experiments aiming tomeasure the CHOOZ angle θ13 and of the experimentalsearches for CP violation in neutrino oscillations.2.2. Review of the present generation of experiments2.2.1. Solar- and reactor-neutrino experiments.ments of the solar-neutrino flux were the first to indicate thatneutrinos undergo flavour oscillations. The first indicationsthat the solar-neutrino flux was smaller than that predicted bythe Standard Solar models came from Davis' experiment atHomestake (USA) [6]. The results of this experiment havebeen confirmed by a series of solar-neutrino experiments,the SAGE experiment in Russia [48], the Gallex and GNOexperiments in Italy [106,107], the Kamiokande and Super-Kamiokande(SK)inJapan[51,108]andfinallybytheSudburyNeutrino Observatory (SNO) in Canada [7,52–54,109]. Inparticular, the neutral current (NC) to charged-current (CC)ratio from the SNO data in 2002 [52] established the presenceofanactiveneutrinoflavourotherthanνeintheobservedsolar-neutrino flux at the 5.3σ level, putting to rest any doubt aboutthe existence of flavour oscillations of solar neutrinos. Furtherevidence was provided by the statistically powerful NC datafrom the salt phase of the SNO experiment [54,109]. Thecumulative result of solar-neutrino data, collected from differ-ent experiments over a period of more than four decades, cul-minated in the emergence of the 'large mixing angle' (LMA)solution as the most favoured explanation of the solar neutrinoproblem.Figure 2 shows the confidence level contours in the?m2all solar-neutrino data combined [77,110,111]. To illustratethe effect of the results from the salt-phase data from SNO, thefigureshowsintheright-handandleft-handpanels,theallowedareas obtained with and without the salt-phase SNO resultsrespectively. The high statistics NC to CC ratio in SNO saltdata,causestheshrinkingoftheallowedregions. Inparticular,the upper bound on both ?m2remarkably.TheKamLANDreactoranti-neutrinoexperimentinJapan[8,55], specifically designed to test the LMA region of thesolar neutrino parameter space, presented its first results in2002, confirming the LMA solution [55]. The higher statisticsdata from this experiment released in 2004 [8] not onlyconfirmed the observed depletion of the reactor anti-neutrinosfrom the first results [55], but for the first time unambiguouslyshowed the existence of an L/E dependence in its positronspectrum, confirming that the observed ¯ νeflavour oscillationswere indeed due to neutrino mass and mixing.Figure 3 [110,111] shows the impact of the first andsecond sets of data from the KamLAND experiment on thesolar-neutrino oscillation parameter space. The current 3σMeasure-21− sin2θ12plane, allowed from the global analysis of21and sin2θ12is seen to improve0.1 0.20.3 0.4sin2θ1210–510–410–3Solar(BP04) [pre-salt](before sept 2003)∆m221/eV2Solar(BP04) [post-salt](after march 2005)90% CL95% CL99% CL99.73% CL0.10.20.30.4 0.510–510–410–3Figure 2. The 90%, 95%, 99% and 99.73% CL contours (for twodegrees of freedom (dof)) show the allowed areas from the globalanalysis of the solar-neutrino data with (right) and without (left) theSNO salt-phase data. Taken with the kind permission of theInternational Journal of Modern Physics from figure 1 in [111].Copyrighted by World Scientific Publishing Company.allowed range of ?m2Bandyopadhyay et al [77,110,111] is given in table 1 alongwith their corresponding 'spread' defined as21and sin2θ12obtained in the analysis ofspread =Pmax− PminPmax+ Pmin× 100,(7)wherePminandPmaxaretheminimumandmaximumallowedvalues of the parameter P at 3σ. The allowed regions werederived on the assumption of CPT invariance and that θ13isnegligible. Also given in table 1 are the bounds on ?m2sin2θ12that are expected to be obtained when additional datafrom the running SNO and KamLAND experiments becomeavailable. For SNO, the analysis assumes that the third andfinalphaseoftheexperimentwillmeasurethesameNCandCCrates as the salt phase, but with reduced errors of 6% and 5%,respectively[112]. ForKamLAND,theprospective3kTydataissimulatedat?m2a systematic error of 5% is assumed. Better measurement ofcharged-current(CC)andneutral-current(NC)ratesinSNOisexpectedtoimprovethelimitsonsin2θ12. ThesensitivityoftheKamLAND experiment to the shape of the reactor-induced ¯ νepositron spectrum, gives the experiment a tremendous abilityto constrain ?m2KamLANDisnotassensitivetothemixingangleθ12[98,113].Theuncertaintyin?m23kTy of data from KamLAND. The uncertainty in sin2θ12is expected to improve after the phase-III results from SNOto 18% at 3σ.This would improve to about 16% if theSNO phase-III projected results are combined with the 3kTysimulated data from KamLAND. However, we note that evenwith the combined data from phase-III of SNO and 3kTystatistics from KamLAND, the uncertainty on sin2θ12wouldstay well above the 10–15% level at 3σ.21and21= 8.0×10−5eV2andsin2θ12= 0.3and21. However, as we can see from table 1,21isexpectedtoreduceto6%at3σ with15
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Easy Granola Bars
Total Time
Prep 15 mins
Cook 10 mins
Leave out the preservative and give your little one something simply good for them. I like to sneak in the grated carrot just to get another vegie into the mix but it's not necessary
Ingredients Nutrition
- 1⁄2 cup light corn syrup
- 2⁄3 cup peanut butter
- 3 cups granola cereal (bought or homemade)
- 1 carrot, grated (optional)
- Butter a 9" square pan.
- In a 3 qt saucepan boil corn syrup for 1 minute only, stirring constantly.
- Remove from heat.
- Stir in peanut butter.
- Stir in granola and grated carrot if using.
- Work fast as it hardens quickly.
- Transfer to pan.
- Spread and pat in place with a spoon or dampened spatula.
- Cool for an hour before cutting into bars.
Most Helpful
I used granola cereal with raisins and almonds in it along with some crushed chex cereal I needed to use up. These were very gooey and fell apart even after a few hours. They tasted good, but had too much PB. Next time I will use less PB and less syrup. Thanks for the simple recipe!
Very, very peanut-buttery. Still, makes for a quick snack that's probably healthier than store bought options. I make my own granola, leave out the carrot and substitute brown rice syrup for the corn syrup (corn syrup is a dirty word these days). Biggest plus here is that these literally take 2 minutes to make. I can press it into a baking dish to cool overnight and it's ready to cut in the morning.
Easy, cheap and good! I subbed 1 cup of krispy rice cereal and 2 cups granola, to make them lighter. these actually made 16 bars -- BONUS! #1 did not like the raisins in the granola, but the rest of us loved these.


text:
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text:
Reports of my death are greatly exaggerated...
Weren't these the same consultancies that were telling firms that if they didn't raise first year associate pay to 160, if they didn't expand unprofitable overseas offices, if they didn't commit to big recruiting programs etc. that they would be left behind?
These guys are nothing but CYA for managing partners and all they do is reinforce what everyone else is doing at the time.
The first thing BigLaw should do is can ZG. Wow, their "insight" is keen.
Somebody get me a bucket....
Perhaps working for big firms is not the most desirable career path.
For twenty years the Professional Inventors Alliance has been working to create create mutually beneficial relationships between inventors and lawyers. Lawyers who enter into symbiotic relationships with inventors help create new wealth, jobs, tax base, and prosperity for all in America.
Small business is the backbone of America. Now is the time to get in on the ground floor. Chart a path towards building a new blockbuster company.
Ronald J. Riley,
Speaking only on my own behalf.
President - http://www.PIAUSA.org - RJR at PIAUSA.org
Executive Director - http://www.InventorEd.org - RJR at InvEd.org
Senior Fellow - http://www.PatentPolicy.org
President - Alliance for American Innovation
Caretaker of Intellectual Property Creators on behalf of deceased founder Paul Heckel
Washington, DC
Direct (810) 597-0194 / (202) 318-1595 - 9 am to 8 pm EST.
I am a third-year student that recently had a offer revoked 7 months after I accepted it. Not only have a I passed on all other opportunities, but I now find myself fighting with 100s of other students for the few remaining positions. I have no sympathy for the partners who are seeing their profits drop.
I wouldn't use the word "symbiotic" to refer to the relationship between lawyers and anyone anywhere within the stream of ordinary commerce. Were it all symbiotic, the insane economics of the legal profession would not even be a topic of conversation.
The partners in large law firms are greedy, all they think about is the dollar. They play with their blackberry and send messages to each other during a meeting with a client and have the gull to bill time for it. They spent 2 hours at a health club and charge time for discovery notes for that 2 hours. It is lie after lie. Staff has to be their Mother and watch over them, etc an baby sit. It is a joke. Most of us entered the law world because we love the law. Little does a new associate learn they come in with a big smile are naive and given $150,000 a year, but, the salary is reducted when the hours are not met for the year, why, because the partner has told the client that the hours will be at a minimum so the little guy loses his pay. They also hire nitwitz for Management giving them sole power to rule and not having any say so with their administering of staff. it is a downright shame. There are some good lawyers and there are some good staff and the peole in between are wernods and jerks.
Great. Now i can say thank you!
The Law Blog covers the legal arena's hot cases, emerging trends and big personalities. It's brought to you by lead writer Jacob Gershman with contributions from across The Wall Street Journal's staff. Jacob comes here after more than half a decade covering the bare-knuckle politics of New York State. His inside-the-room reporting left him steeped in legal and regulatory issues that continue to grab headlines.
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1 Park near Fargo, North Dakota
West Fargo, North Dakota 4.71 miles SW
Casselton, North Dakota 19.53 miles W
Leonard, North Dakota 26.97 miles SW
Hillsboro, North Dakota 37.12 miles NW
Enderlin, North Dakota 42.41 miles SW
Fargo, North Dakota (map) | (701) 232-3987
Sites: 58 | Latest Rate: $25.00 | 28 Reviews
|Clean Restrooms:
|Clean Showers:
Sep 2015 - $25.00
Very tight spaces in the upper campground areas where we were camped. You're on top of the next camper with just a small grassy area between you and the next camper especially if you both have slide outs. Awnings when extended would almost cover to the next camper. Our site had low spots which had water standing in it after a rain and became muddy. - LabDad2
Aug 2015 - $29.00
Beautiful Park and great for walkers. The upper campground is super tight sites. The lower is near the river nice but we were downwind of the trash so pew. Very convenient location and nice size sites where we stayed. - BonT
Jul 2015 - $40.00
Stayed for a few weeks with my family in this park while in the area for a medical emergency. We were in the A loop which has some sites with nice grass and spacing, while others barely allow an open awning without touching another site. I did notice some vagrants and late night activity here that made me a bit nervous. Bike path along the Red River was very nice and allowed for easy bicycle commutes to downtown. Overall Fargo the town was very surprising, some great places to eat and good shopping. Unfortunately this is the only game in town as far as campgrounds go, so if you need to stay in Fargo this is your best (and almost only) bet. Cell coverage and internet was good, no wifi available. Also no sewer sites, only W/E. - pokeyt


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Good bye everyone.
You will find me later as Dead Citizen.
Thanks for everything. Don't ask me why. Because it will hurt me. It is enough to keep it secret.
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