Lattice results for the decay constant of heavy-light vector mesons

TL;DR

This paper uses lattice QCD to compute decay constants of heavy-light vector mesons, validating the approach against Heavy Quark Effective Theory and providing specific decay constant ratios and values for B mesons.

Contribution

It presents the first lattice QCD calculation of the decay constant ratio for B mesons and compares it with theoretical predictions, confirming the reliability of the method.

Findings

Decay constant ratio for B mesons: 1.01(0.01)(+0.04-0.01)

Quenched decay constant for B*: 177(6)(17) MeV

Good agreement with Heavy Quark Effective Theory

Abstract

We compute the leptonic decay constants of heavy-light vector mesons in the quenched approximation. The reliability of lattice computations for heavy quarks is checked by comparing the ratio of vector to pseudoscalar decay constant with the prediction of Heavy Quark Effective Theory in the limit of infinitely heavy quark mass. Good agreement is found. We then calculate the decay constant ratio for B mesons: $f_{B^*}/f_B= 1.01(0.01)(^{+0.04}_{-0.01})$. We also quote quenched $f_{B^*}=177(6)(17)$ MeV.