E. Follana

High-precision determination of the pi, K, D, and D-s decay constants from lattice QCD

We determine D and D(s) decay constants from lattice QCD with 2% errors, 4 times better than experiment and previous theory: f(D(s))=241(3) MeV, f(D)=207(4) MeV, and fD(s))/f(D)=1.164(11). We also obtain f(K)/f(pi)=1.189(7) and (f(D(s))/f(D))/(f(K)/f(pi))=0.979(11). Combining with experiment gives V(us)=0.2262(14) and V(cs)/V(cd) of 4.43(41). We use a highly improved quark discretization on MILC gluon fields that include realistic sea quarks, fixing the u/d, s, and c masses from the pi, K, and eta(c) meson masses. This allows a stringent test against experiment for D and D(s) masses for the first time (to within 7 MeV).

High-Precision c and b Masses, and QCD Coupling from Current-Current Correlators in Lattice and Continuum QCD

We extend our earlier lattice-QCD analysis of heavy-quark correlators to smaller lattice spacings and larger masses to obtain new values for the c mass and QCD coupling, and, for the first time, values for the b mass: m{sub c}(3 GeV,n{sub f}=4)=0.986(6) GeV, {alpha}{sub MS}(M{sub Z},n{sub f}=5)=0.1183(7), and m{sub b}(10 GeV,n{sub f}=5)=3.617(25) GeV. These are among the most accurate determinations by any method. We check our results using a nonperturbative determination of the mass ratio m{sub b}({mu},n{sub f})/m{sub c}({mu},n{sub f}); the two methods agree to within our 1% errors and taken together imply m{sub b}/m{sub c}=4.51(4). We also update our previous analysis of {alpha}{sub MS} from Wilson loops to account for revised values for r{sub 1} and r{sub 1}/a, finding a new value {alpha}{sub MS}(M{sub Z},n{sub f}=5)=0.1184(6); and we update our recent values for light-quark masses from the ratio m{sub c}/m{sub s}. Finally, in the Appendix, we derive a procedure for simplifying and accelerating complicated least-squares fits.

Highly improved staggered quarks on the lattice, with applications to charm physics

We use perturbative Symanzik improvement to create a new staggered-quark action (HISQ) that has greatly reduced one-loop taste-exchange errors, no tree-level order a{sup 2} errors, and no tree-level order (am){sup 4} errors to leading order in the quarks velocity v/c. We demonstrate with simulations that the resulting action has taste-exchange interactions that are 3-4 times smaller than the widely used ASQTAD action. We show how to bound errors due to taste exchange by comparing ASQTAD and HISQ simulations, and demonstrate with simulations that such errors are likely no more than 1% when HISQ is used for light quarks at lattice spacings of 1/10 fm or less. The suppression of (am){sup 4} errors also makes HISQ the most accurate discretization currently available for simulating c quarks. We demonstrate this in a new analysis of the {psi}-{eta}{sub c} mass splitting using the HISQ action on lattices where am{sub c}=0.43 and 0.66, with full-QCD gluon configurations (from MILC). We obtain a result of 111(5) MeV which compares well with the experiment. We discuss applications of this formalism to D physics and present our first high-precision results for D{sub s} mesons.

Update: Precision D_s decay constant from full lattice QCD using very fine lattices

We update our previous determination of both the decay constant and the mass of the D s meson using the highly improved staggered quark formalism. We include additional results at two finer values of the lattice spacing along with improved determinations of the lattice spacing and improved tuning of the charm and strange quark masses. We obtain m Ds = 1.9691(32) GeV, in good agreement with experiment, and f Ds = 0.2480(25) GeV. Our result for f Ds is 1.6σ lower than the most recent experimental average determined from the D s leptonic decay rate and using V cs from Cabibbo-Kobayashi-Maskawa unitarity. Combining our f Ds with the experimental rate we obtain a direct determination of V cs = 1.010(22), or alternatively 0.990 +0.013 -0.016 using a probability distribution for statistical errors for this quantity which vanishes above 1. We also include an accurate prediction of the decay constant of the η c , f ηc = 0.3947(24) GeV, as a calibration point for other lattice calculations.

High-Precision Charm-Quark Mass from Current-Current Correlators in Lattice and Continuum QCD

We use lattice QCD simulations, with MILC configurations and HISQ

High-precision fBs and heavy quark effective theory from relativistic lattice QCD

c

Precision tests of the J / ψ from full lattice QCD: Mass, leptonic width, and radiative decay rate to η c

-quark propagators, to make very precise determinations of moments of charm-quark pseudoscalar, vector and axial-vector correlators. These moments are combined with new four-loop results from continuum perturbation theory to obtain several new determinations of the

Precise Charm to Strange Mass Ratio and Light Quark Masses from Full Lattice QCD

\msb

The Upsilon spectrum and the determination of the lattice spacing from lattice QCD including charm quarks in the sea

mass of the charm quark. We find

Precise determination of the lattice spacing in full lattice QCD

m_c(3 \mathrm{GeV})=0.984 (16)