Dynamical lattice computation of the Isgur-Wise functions tau_{1/2} and tau_{3/2}

TL;DR

This study uses lattice QCD to compute Isgur-Wise functions tau_{1/2} and tau_{3/2} at zero recoil, providing insights into semileptonic B meson decays and addressing the 1/2 versus 3/2 puzzle.

Contribution

First lattice computation of tau_{1/2} and tau_{3/2} functions at zero recoil in the static limit with dynamical quarks, contributing to understanding of B meson decay puzzles.

Findings

tau_{1/2}(1) = 0.297(26)

tau_{3/2}(1) = 0.528(23)

Fulfill Uraltsev's sum rule by around 80%

Abstract

We perform a two-flavor dynamical lattice computation of the Isgur-Wise functions tau_{1/2} and tau_{3/2} at zero recoil in the static limit. We find tau_{1/2}(1) = 0.297(26) and tau_{3/2}(1) = 0.528(23) fulfilling Uraltsev's sum rule by around 80%. We also comment on a persistent conflict between theory and experiment regarding semileptonic decays of B mesons into orbitally excited P wave D mesons, the so-called "1/2 versus 3/2 puzzle", and we discuss the relevance of lattice results in this context.