Charm physics with overlap fermions on 2+1-flavor domain wall fermion configurations

TL;DR

This paper calculates decay constants of various charm mesons using lattice QCD with overlap fermions on domain wall configurations, improving discretization error understanding and providing precise decay constant ratios and branching fractions.

Contribution

It introduces a lattice QCD calculation of charm meson decay constants using overlap fermions on 2+1-flavor domain wall configurations, enhancing precision and discretization error analysis.

Findings

Decay constants for $D$, $D_s$, $ ext{eta}_c$, $D^*$, $D_s^*$, $J/\psi$ determined.

Ratio $f_{D_s^*}^T/f_{D_s^*}$ obtained with improved precision.

Branching fraction for $D_s^*$ leptonic decay estimated.

Abstract

Decay constants of pseudoscalar mesons $D$, $D_s$, $\eta_c$ and vector mesons $D^*$, $D_s^*$, $J/\psi$ are determined from $N_f=2+1$ lattice QCD at a lattice spacing $a\sim0.08$ fm. For vector mesons, the decay constants defined by tensor currents are given in the $\overline{\rm MS}$ scheme at $2$ GeV. The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations and the overlap fermion action is used for the valence quarks. Comparing the current results with our previous ones at a coarser lattice spacing $a\sim0.11$ fm gives us a better understanding of the discretization error. We obtain $f_{D_s^*}^T(\overline{\rm MS},\text{2 GeV})/f_{D_s^*}=0.907(20)$ with a better precision than our previous result. Combining our $f_{D_s^*}=277(11)$ MeV with the total width of $D_s^*$ determined in a recent work gives a branching fraction $4.26(52)\times10^{-5}$ for $D_s^*$ leptonic decay.