First lattice QCD calculation of J/ψ semileptonic decay containing D and Dₛ particles

We perform the first lattice calculation on the semileptonic decay of J/ψ using the (2+1)-flavor Wilson-clover gauge ensembles generated by CLQCD collaboration. Three gauge ensembles with different lattice spacings, from 0.0519 fm to 0.1053 fm, and pion masses, mπ~ 300 MeV, are utilized. After a naive continuum extrapolation using three lattice spacings, we obtain Br(J/ψ→ Dₛ eνₑ)=1.90(6)(5)_Vcs× 10⁻¹⁰ and Br(J/ψ→ D eνₑ)=1.21(6)(9)_Vcd× 10⁻¹¹, where the first errors are statistical, and the second come from the uncertainties of CKM matrix element Vcs(d). The ratios of the branching fractions between lepton μ and e are also calculated as RJ/ψ(Dₛ)=0.97002(8) and RJ/ψ(D)=0.97423(15) after performing a continuum limit including only a² term. The ratios provide necessary theoretical support for the future experimental test of lepton flavor universality.