English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We calculate the leptonic decay constants of heavy-light pseudoscalar mesonswith charm and bottom quarks in lattice quantum chromodynamics on four-flavorQCD gauge-field configurations with dynamical $u$, $d$, $s$, and $c$ quarks. Weanalyze over twenty isospin-symmetric ensembles with six lattice spacings downto $a\approx 0.03$~fm and several values of the light-quark mass down to thephysical value $\frac{1}{2}(m_u+m_d)$. We employ the highly-improvedstaggered-quark (HISQ) action for the sea and valence quarks; on the finestlattice spacings, discretization errors are sufficiently small that we cancalculate the $B$-meson decay constants with the HISQ action for the first timedirectly at the physical $b$-quark mass. We obtain the most precisedeterminations to-date of the $D$- and $B$-meson decay constants and theirratios, $f_{D^+} = 212.7(0.6)$~MeV, $f_{D_s} = 249.9(0.4)$~MeV,$f_{D_s}/f_{D^+} = 1.1749(16)$, $f_{B^+} = 189.4 (1.4)$~MeV, $f_{B_s} =230.7(1.3)$~MeV, $f_{B_s}/f_{B^+} = 1.2180(47)$, where the errors includestatistical and all systematic uncertainties. Our results for the $B$-mesondecay constants are three times more precise than the previous best lattice-QCDcalculations, and bring the QCD errors in the Standard-Model predictions forthe rare leptonic decays $\overline{\mathcal{B}}(B_s \to \mu^+\mu^-) = 3.64(11)\times 10^{-9}$, $\overline{\mathcal{B}}(B^0 \to \mu^+\mu^-) = 1.00(3) \times10^{-10}$, and $\overline{\mathcal{B}}(B^0 \to\mu^+\mu^-)/\overline{\mathcal{B}}(B_s \to \mu^+\mu^-) = 0.0273(9)$ to wellbelow other sources of uncertainty. As a byproduct of our analysis, we alsoupdate our previously published results for the light-quark-mass ratios and thescale-setting quantities $f_{p4s}$, $M_{p4s}$, and $R_{p4s}$. We obtain themost precise lattice-QCD determination to date of the ratio $f_{K^+}/f_{\pi^+}= 1.1950(^{+16}_{-23})$~MeV.

$B$- and $D$-meson leptonic decay constants from four-flavor lattice QCD