Semileptonic decaysB→πlνandD→<

Abstract

We present a lattice QCD calculation of the form factors and differential decay rates for semileptonic decays of the heavy-light mesons B and D to the final state l . The results are obtained with three methodological improvements over previous lattice calculations: a matching procedure that reduces heavy-quark lattice artifacts, the first study of lattice-spacing dependence, and the introduction of kinematic cuts to reduce model dependence. We show that the main systematics are controllable ͑within the quenched approximation͒ and outline how the calculations could be improved to aid current experiments in the determination of ͉V ub ͉ and ͉V cd ͉.

Semileptonic and decays in flavor lattice QCD

“…[6], and carry out the chiral extrapolation in m l for them at fixed E. To this end, we interpolate and extrapolate the results for f and f ⊥ to common values of E using the parametrization of Becirevic and Kaidalov (BK) [9]. We perform the chiral extrapolation using the NLO correction in staggered chiral perturbation theory (SχPT) [10].…”

Lattice QCD and the unitarity triangle

“…It is, thus, timely to compare and contrast. In addition to discretization effects at large pa, there is evidence for considerable dependence on the light spectator quark mass [24].…”

“…In the past year or so, four new quenched calculations of f ·´E µ for B πlν appeared, using several different methods [22,23,24,25]. It is, thus, timely to compare and contrast.…”

The Status of ∣Vub∣

“…Recent advances may also allow use of the full q 2 range for extraction of |V ub | with LQCD [112,113]. For both LQCD and experiment, πℓν appears to be the golden mode -even the B * pole now appears manageable [68]. B → ηℓν will provide a valuable cross-check.…”

“…A large variety of calculations exist. For extraction of |V ub |, the focus has sharpened onto the QCD-based calculations of lattice QCD (LQCD) [57,58,59,60,61,62,63,64,65,66,67,68,69] and light cone sum rules (LCSR) [70,71,72,73,74,75,76,77,78]. Only quenched LQCD FF calculations are available for b → uℓν, and these have sensitivity only in the range q 2 16 GeV 2 .…”