Implications of SU(2)_L x U(1) Symmetry for SIM(2) Invariant Neutrino   Masses
  We consider SU(2)_L x U(1) gauge invariant generalizations of a nonlocal, Lorentz violating mass term for neutrinos that preserves a SIM(2) subgroup. This induces Lorentz violating effects in QED as well as tree-level lepton family number violating interactions. Measurements of g_e - 2 with trapped electrons severely constrain possible SIM(2) mass terms for electrons which violate C invariance. We study Lorentz violating effects in a C invariant and SIM(2) invariant extension of QED. We examine the Lorentz violating interactions of nonrelativistic electrons with electromagnetic fields to determine their impact on the spectroscopy of hydrogen-like atoms and g_e - 2 measurements with trapped electrons. Generically, Lorentz violating corrections are suppressed by m_\nu^2/m_e^2 and are within experimental limits. We study one-loop corrections to electron and photon self-energies and point out the need for a prescription to handle IR divergences induced by the nonlocality of the theory. We also calculate the tree level contribution to \mu to e + \gamma from SIM(2) invariant mass terms. 
Alan Dunn (Duke University), Thomas Mehen (Duke University, Jefferson   Laboratory)