Neutral B-meson mixing parameters in and beyond the SM with 2+1 flavor   lattice QCD
  We report on the status of our calculation of the hadronic matrix elements for neutral $B$-meson mixing with asqtad sea and valence light quarks and using the Wilson clover action with the Fermilab interpretation for the $b$ quark. We calculate the matrix elements of all five local operators that contribute to neutral $B$-meson mixing both in and beyond the Standard Model. We use MILC ensembles with $N_f=2+1$ dynamical flavors at four different lattice spacings in the range $a \approx 0.045$--$0.12$~fm, and with light sea-quark masses as low as 0.05 times the physical strange quark mass. We perform a combined chiral-continuum extrapolation including the so-called wrong-spin contributions in simultaneous fits to the matrix elements of the five operators. We present a complete systematic error budget and conclude with an outlook for obtaining final results from this analysis. 
C.M. Bouchard, E.D. Freeland, C.W. Bernard, C.C. Chang, A.X.El-Khadra,   M.E. G\'amiz, A.S. Kronfeld, J. Laiho, R.S. Van de ...
hep-lat hep-ph