James N. Simone

B- and D-meson decay constants from three-flavor lattice QCD

We calculate the leptonic decay constants ofB (s) andD (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 congurations which include the eects of three light dynamical sea quarks. We simulate with several values of the light valence- and sea-quark masses (down to ms=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 obtain f B+ = 196:9(8:9) MeV, fBs = 242:0(9:5) MeV, f D+ = 218:9(11:3) MeV, fDs = 260:1(10:8) MeV, and the SU(3) avor-breaking ratios fBs =fB = 1:229(26) and fDs =fD = 1:188(25), where the numbers in parentheses are the total statistical and systematic uncertainties added in quadrature.

Semileptonic decays of d mesons in three-flavor lattice QCD.

We present the first three-flavor lattice QCD calculations for D-->pilnu and D-->Klnu semileptonic decays. Simulations are carried out using ensembles of unquenched gauge fields generated by the MILC Collaboration. With an improved staggered action for light quarks, we are able to simulate at light quark masses down to 1/8 of the strange mass. Consequently, the systematic error from the chiral extrapolation is much smaller than in previous calculations with Wilson-type light quarks. Our results for the form factors at q(2)=0 are f(D-->pi)(+)(0)=0.64(3)(6) and f(D-->K)(+)(0)=0.73(3)(7), where the first error is statistical and the second is systematic, added in quadrature. Combining our results with experimental branching ratios, we obtain the Cabibbo-Kobayashi-Maskawa matrix elements |V(cd)|=0.239(10)(24)(20) and |V(cs)|=0.969(39)(94)(24), where the last errors are from experimental uncertainties.

B →d ν form factors at nonzero recoil and |Vcb | from 2+1 -flavor lattice QCD

We present the first unquenched lattice-QCD calculation of the hadronic form factors for the exclusive decay

Semileptonic D→π/K and B→π/D decays in 2+1 flavor lattice QCD

\overline{B}\ensuremath{\rightarrow}D\ensuremath{\ell}\overline{\ensuremath{\nu}}

Charmed-meson decay constants in three-flavor lattice QCD

at nonzero recoil. We carry out numerical simulations on 14 ensembles of gauge-field configurations generated with

B→πlν semileptonic form factor from three-flavor lattice QCD: A model-independent determination of |Vub|

2+1

B(s)0-mixing matrix elements from lattice QCD for the Standard Model and beyond

flavors of asqtad-improved staggered sea quarks. The ensembles encompass a wide range of lattice spacings (approximately 0.045 to 0.12 fm) and ratios of light (up and down) to strange sea-quark masses ranging from 0.05 to 0.4. For the

Refining new-physics searches in B→Dτν with lattice QCD.

b

B̄→D*ℓν̄ form factor at zero recoil from three-flavor lattice QCD: A model independent determination of |Vcb|

and

Mass of the B(c) meson in three-flavor lattice QCD

c