出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We present a (2+1)-flavor lattice QCD calculation of the form factor ratio between the semilep- tonic decays ¯B 0s →D+s l− ¯ ν and ¯B0 →D+l−ν¯ . This ratio is an important theoretical input to the hadronic determination of the B meson fragmentation fraction ratio fs/ fd which enters in the mea- surement of BR(B0s →μ+μ−). Small lattice spacings and high statistics enable us to simulate the decays with a dynamic final D meson of small momentum and reliably extract the hadronic ma- trix elements at nonzero recoil. We report our preliminary result for the form factor ratio at the corresponding momentum transfer of the two decays f (s) 0 (M2π)/ f (d) 0 (M2K ).
