K. Hornbostel

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.

Constrained curve fitting

We survey techniques for constrained curve fitting, based upon Bayesian statistics, that offer significant advantages over conventional techniques used by lattice field theorists.

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

Precision [Upsilon] spectroscopy from nonrelativistic lattice QCD

\msb

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

mass of the charm quark. We find

New determination of the pole mass of the b quark using lattice QCD.

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

Bc spectroscopy from lattice QCD

GeV, or, equivalently,