Bottomonium hyperfine splittings from lattice NRQCD including radiative and relativistic corrections

We present a calculation of the hyperfine splittings in bottomonium using lattice Nonrelativistic QCD. The calculation includes spin-dependent relativistic corrections through O(v^6), radiative corrections to the leading spin-magnetic coupling and, for the first time, non-perturbative 4-quark interactions which enter at alpha_s^2 v^3. We also include the effect of u,d,s and c quark vacuum polarisation. Our result for the 1S hyperfine splitting is M(Upsilon,1S) - M(eta_b,1S)= 60.0(6.4) MeV. We find the ratio of 2S to 1S hyperfine splittings (M(Upsilon,2S) - M(eta_b,2S))/ (M(Upsilon,1S) - M(eta_b,1S)) = 0.445(28).

B, Bs, K and pi weak matrix elements with physical light quarks

Calculations of pseudoscalar decay constants of B, Bs, K and pi mesons with physical light quarks are presented. We use HISQ ensembles that include u,d,s and c sea quarks at three lattice spacings. HISQ is used for the valence light quarks and a radiatively improved NRQCD action for the heavy quarks. The key results are f_{B^+}=0.184(4)$ GeV, f_{B_s}=0.224(4) GeV, f_{B_s}/f_{B^+}=1.217(8), f_{K^+}/f_{pi^+}=1.1916(21), f_{K^+}=155.37(34) MeV, giving a significant improvement over previous results that required chiral extrapolation. We also calculate the Wilson flow scale w_0, finding w_0=0.1715(9) fm.

Precise heavy-light meson masses and hyperfine splittings from lattice QCD including charm quarks in the sea

We present improved results for the B and D meson spectrum from lattice QCD including the effect of u/d,s and c quarks in the sea. For the B mesons the Highly Improved Staggered Quark action is used for the sea and light valence quarks and NonRelativistic QCD for the b quark including O(alpha_s) radiative corrections to many of the Wilson coefficients for the first time. The D mesons use the Highly Improved Staggered Quark action for both valence quarks on the same sea. We find M_{B_s}-M_B=84(2) MeV, M_{B_s}=5.366(8) GeV, M_{B_c}=6.278(9) GeV, M_{D_s}=1.9697(33) GeV, and M_{D_s}-M_{D}=101(3) MeV. Our results for the B meson hyperfine splittings are M_{B^*}-M_{B}=50(3) MeV, M_{B_s^*}-M_{B_s}=52(3) MeV, in good agreement with existing experimental results. This demonstrates that our perturbative improvement of the NRQCD chromo-magnetic coupling works for both heavyonium and heavy-light mesons. We predict M_{B_c^*}-M_{B_c}=54(3) MeV. We also present first results for the radially excited B_c states as well as the orbitally excited scalar B_c0^* and axial vector B_c1 mesons.