## Abstract

We calculate the leptonic decay constants of B _{(s)} and D _{(s)} mesons in lattice QCD using staggered light quarks and Fermilab bottom and charm quarks. We compute the heavy-light-meson correlation functions on the MILC Asqtad-improved staggered gauge configurations, which include the effects of three light dynamical sea quarks. We simulate with several values of the light valence- and sea-quark masses (down to ∼m _{s}/10) and at three lattice spacings (a≈0.15, 0.12, and 0.09 fm) and extrapolate to the physical up and down quark masses and the continuum using expressions derived in heavy-light-meson staggered chiral perturbation theory. We renormalize the heavy-light axial current using a mostly nonperturbative method such that only a small correction to unity must be computed in lattice perturbation theory, and higher-order terms are expected to be small. We use the two finer lattice spacings for our central analysis, and we use the third to help estimate discretization errors. We obtain f _{B}+=196.9(9.1)MeV, f _{Bs}=242.0(10.0)MeV, f _{D} ^{+}=218.9(11.3)MeV, f _{D}s=260.1(10.8)MeV, and the SU(3) flavor-breaking ratios f _{Bs}/f _{B}=1.229(26) and f _{Ds}/f _{D}=1.188(25) , where the numbers in parentheses are the total statistical and systematic uncertainties added in quadrature.

Original language | English (US) |
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Article number | 114506 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 85 |

Issue number | 11 |

DOIs | |

State | Published - Jun 8 2012 |

## ASJC Scopus subject areas

- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)