Precision lattice QCD computation of the B^{⁎} Bπ coupling
Abstract
The static B^{⁎} Bπ coupling, g_{ˆχ}, a low energy constant in the leading order heavy meson chiral Lagrangian, is determined using N_{f} = 2 lattice QCD. We use CLS ensembles with lattice spacings and pion masses down to a = 0.05 fm and m_{π} = 270 MeV, and perform combined continuum and chiral extrapolations of our results which have a much better accuracy than previous numbers in the literature. As a byproduct, we determine the coupling between the first radial excitations in the B and B^{⁎} channels (g_{ˆ22}). Accounting for all uncertainties, which are dominated by the chiral extrapolation, we obtain g_{ˆχ} = 0.492 (29), while g_{ˆ22} is somewhat smaller. The comparison to a precise quenched computation suggests that there is little influence by the sea quarks and g_{ˆχ} will not change much when a dynamical strange quark is included.
 Publication:

Physics Letters B
 Pub Date:
 January 2015
 DOI:
 10.1016/j.physletb.2014.11.051
 arXiv:
 arXiv:1404.6951
 Bibcode:
 2015PhLB..740..278B
 Keywords:

 Lattice QCD;
 Heavy quark effective theory;
 Bottom quarks;
 Heavy meson chiral effective theory;
 High Energy Physics  Lattice
 EPrint:
 14 pages, all included