B meson decays from moving-NRQCD on fine MILC lattices

TL;DR

This paper demonstrates how moving-NRQCD formalism enables accurate lattice simulations of B meson decays at high momentum, overcoming previous low q^2 region challenges, and discusses non-perturbative and perturbative renormalization methods.

Contribution

It introduces a complete simulation framework for B mesons using moving-NRQCD on fine MILC lattices, including mass determination and renormalization techniques.

Findings

B and B* masses as a function of velocity v

Non-perturbative determination of meson kinetic mass

Perturbative renormalization from high-beta Monte Carlo simulations

Abstract

Lattice simulations of $B\to\pi l\nu$ decays are problematic in the low $q^{2}$ region when the pion has to have large momentum in the lattice frame for a $B$ meson at rest or moving slowly. The moving-NRQCD formalism provides a way around this by giving an accurate discretization of a $b$ quark moving at arbitrary velocity $v$, and therefore a $B$ meson moving at high momentum in the lattice frame. Here we show results from simulations of the moving-NRQCD action complete through $O(1/M)$ coupled to the asqtad action on a MILC fine ensemble. We show $B$, $B^{*}$ masses as a function of $v$ and demonstrate how to determine the meson kinetic mass and the renormalization of $v$ non-perturbatively. We will also discuss the perturbative renormalization of the moving-NRQCD action from high-$\beta$ Monte Carlo simulations.