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

Abstract

Decay constants of pseudoscalar mesons $D$, $D_s$, ${\eta }_c$ and vector mesons $D^{\ast }$, $D_s^{\ast }$, $J/\psi$ are determined from $N_f=2+1$ lattice QCD at a lattice spacing $a\sim 0.08$ fm. For vector mesons, the decay constants defined by tensor currents are given in the $\overline{\mathrm{MS}}$ 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 $a\sim 0.11$ fm gives us a better understanding of the discretization error. We obtain $f_{D_s^{\ast }}^T(\overline{\mathrm{MS}},\text{2 GeV})/f_{D_s^{\ast }}=0.907(20)$ with a better precision than our previous result. Combining our $f_{D_s^{\ast }}=277(11)$ MeV with the total width of $D_s^{\ast }$ determined in a recent work gives a branching fraction $4.26(52)\times 10^{-5}$ for $D_s^{\ast }$ leptonic decay.

Comments: 18 pages, 7 figures, 12 tables