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

Abstract

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 Oð s Þ 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 À M B ¼ 84ð2Þ MeV, M B s ¼ 5:366ð8Þ GeV, M B c ¼ 6:278ð9Þ GeV, M D s ¼ 1:9697ð33Þ GeV, and M D s À M D ¼ 101ð3Þ MeV. Our results for the B meson hyperfine splittings are M B Ã À M B ¼ 50ð3Þ MeV, M B Ã s À M B s ¼ 52ð3Þ MeV, in good agreement with existing experimental results. This demonstrates that our perturbative improvement of the nonrelativistic QCD chromomagnetic coupling works for both heavyonium and heavylight mesons. We predict M B Ã c À M B c ¼ 54ð3Þ MeV. We also present first results for the radially excited B c states as well as the orbitally excited scalar B Ã c0 and axial-vector B c1 mesons.

B-meson decay constants: A more complete picture from full lattice QCD

“…Including the one-loop radiative corrections to c 4 is particularly important here, since this coefficient controls the hyperfine splitting between the vector and pseudoscalar states. We showed in [10] that improving c 4 leads to accurate results for b-light hyperfine splittings in keeping with the results of [6] for bottomonium. Most of the correlators we use here for determining the vector heavy-light meson decay constants come from the same calculation as that of [10].…”

“…The action used here builds on the standard NRQCD action [19] accurate through v 4 in the heavy quark velocity v (using power-counting terminology for bottomonium) by including one-loop radiative corrections to many of the v 4 coefficients [6,20]. We studied the effect of these improvements on the bottomonium spectrum in [6,21,22] and in B, B s and B c meson masses in [10].…”

“…The current state of the art [5,10] uses an improved NRQCD action for the heavy quark coupled to a HISQ light quark on gluon configurations that include an improved gluon action and HISQ sea quarks. Here we extend these calculations to include the decay constants of vector heavylight mesons.…”

“…We begin by outlining the methods used in our lattice calculation, which follow [5,10]. Section III A gives results for the decay constants of the B Section III E works with quarks lighter than b to demonstrate the heavy quark mass dependence of the decay constants and compare to our earlier results using the HISQ formalism for b quarks.…”

Recent results on the meson and baryon spectrum from lattice QCD

“…Improved actions have been developed for simulations with both light (u,d,s) and heavy (c,b) quarks, allowing for a reliable extraction of simple observables for mesons made from these quarks. Figure 1 (from [1]) shows results for the lattice spectrum of states stable or nearly stable under the strong interaction compared to experiment. After some of the experimental masses are used as input to tune the mass parameters and coupling in the action (cyan crosses in the figure), parameter free theory postdictions and predictions were obtained.…”