New methods for B meson decay constants and form factors from lattice NRQCD

We determine the normalization of scalar and pseudoscalar current operators made from nonrelativistic b quarks and highly improved staggered light quarks in lattice quantum chromodynamics (QCD) through O(alpha(s)) and Lambda(QCD)/m(b). We use matrix elements of these operators to extract B meson decay constants and form factors, and then compare to those obtained using the standard vector and axial-vector operators. This provides a test of systematic errors in the lattice QCD determination of the B meson decay constants and form factors. We provide a new value for the B and B-s meson decay constants from lattice QCD calculations on ensembles that include u, d, s, and c quarks in the sea and those that have the u/d quark mass going down to its physical value. Our results are f(B) = 0.196(6) GeV, f(Bs) = 0.236(7) GeV, and f(Bs)/f(B) = 1.207(7), agreeing well with earlier results using the temporal axial current. By combining with these previous results, we provide updated values of f(B) = 0.190(4) GeV, f(Bs) = 0.229(5) GeV, and f(Bs)/f(B) = 1.206(5).