0000000000850232
AUTHOR
L. Silvestrini
D-0 - (D)over-bar(0) mixing in the standard model and beyond from N-f=2 twisted mass QCD
We present the first unquenched lattice QCD results for the bag parameters controlling the short distance contribution to D meson oscillations in the standard model and beyond. We have used the gauge configurations produced by the European Twisted Mass collaboration with N-f = 2 dynamical quarks, at four lattice spacings and light meson masses in the range 280-500 MeV. Renormalization is carried out nonperturbatively with the regularization-independent momentum subtraction method. The bag-parameter results have been used to constrain new physics effects in D-0 ¿ (D) over bar (0) mixing, to put a lower bound to the generic new physics scale and to constrain off-diagonal squark mass terms for…
Delta M_K and epsilon_K in SUSY at the Next-to-Leading order
We perform a Next-to-Leading order analysis of Delta S=2 processes beyond the Standard Model. Combining the recently computed NLO anomalous dimensions and the B parameters of the most general Delta S=2 effective Hamiltonian, we give an analytic formula for Delta M_K and epsilon_K in terms of the Wilson coefficients at the high energy scale. This expression can be used for any extension of the Standard Model with new heavy particles. Using this result, we consider gluino-mediated contributions to Delta S=2 transitions in general SUSY models and provide an improved analysis of the constraints on off-diagonal mass terms between the first two generations of down-type squarks. Finally, we improv…
B(d) - anti-B(d) mixing and the B(d) ---> J / psi K(s) asymmetry in general SUSY models
We present a next-to-leading order determination of the gluino-mediated SUSY contributions to B-d-(B) over bard mixing and to the CP asymmetry a(J)/psiK(s) in the framework of the mass-insertion approximation. Using hadronic matrix elements recently computed on the lattice, we obtain improved constraints on the squark-mass splittings.