B meson decay constants from 2 +1 flavor lattice QCD with domainwall light quarks and relativistic heavy quarks
Abstract
We calculate the B meson decay constants f_{B} , f_{Bs} , and their ratio in unquenched lattice QCD using domainwall light quarks and relativistic b quarks. We use gaugefield ensembles generated by the RBC and UKQCD collaborations using the domainwall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈0.11 , 0.086 fm with unitary pion masses as light as M_{π}≈290 MeV ; this enables us to control the extrapolation to the physical lightquark masses and continuum. For the b quarks we use the anisotropic clover action with the relativistic heavyquark interpretation, such that discretization errors from the heavyquark action are of the same size as from the lightquark sector. We renormalize the lattice heavylight axialvector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavylight current through O (α_{s}a ) . We extrapolate our results to the physical lightquark masses and continuum using SU(2) heavymeson chiral perturbation theory, and provide a complete systematic error budget. We obtain f_{B0}=199.5 (12.6 ) MeV , f_{B+}=195.6 (14.9 ) MeV , f_{Bs}=235.4 (12.2 ) MeV , f_{Bs}/f_{B0}=1.197 (50 ) , and f_{Bs}/f_{B+}=1.223 (71 ) , where the errors are statistical and total systematic added in quadrature. These results are in good agreement with other published results and provide an important independent crosscheck of other threeflavor determinations of B meson decay constants using staggered light quarks.
 Publication:

Physical Review D
 Pub Date:
 March 2015
 DOI:
 10.1103/PhysRevD.91.054502
 arXiv:
 arXiv:1404.4670
 Bibcode:
 2015PhRvD..91e4502C
 Keywords:

 11.15.Ha;
 12.38.Gc;
 13.20.He;
 14.40.Nd;
 Lattice gauge theory;
 Lattice QCD calculations;
 Decays of bottom mesons;
 Bottom mesons;
 High Energy Physics  Lattice;
 High Energy Physics  Phenomenology
 EPrint:
 25 pages, 13 tables, 12 figures. Version 2 revised for PRD. Sign in Eq. (27) corrected. Chiralcontinuum extrapolations of fB and fBs/fB changed. Results for fB and fBs/fB, plots, and text updated accordingly. Updated references