M. Nobes

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

We present results for form factors of semileptonic decays of D and B mesons in 2 + 1 flavor lattice QCD using the MILC gauge configurations. With an improved staggered action for light quarks, we successfully reduce the systematic error from the chiral extrapolation. The results for D decays are in agreement with experimental ones. The results for B decays are preliminary. Combining our results with experimental branching ratios, we then obtain the CKM matrix elements | V c d | , | V c s | , | V c b | and | v u b | . We also check CKM unitarity, for the first time, using only lattice QCD as the theoretical input.

Decays of the Bc meson in a relativistic quark-meson model

The semileptonic decay form factors of the double heavy Bc meson provide a unique opportunity to study the strong interactions between two heavy quarks. A fully relativistic model, with effective non-local quark-meson interactions, is used to compute semileptonic decay form factors, for both the Bc and a wide range of other heavy-light mesons. Using these form factors predictions for decay rates and branching ratios are obtained. The results are compared with other theoretical approaches and, where available, to experimental results. In addition, the radiative decay of B*c is discussed.

Second order perturbation theory for improved gluon and staggered quark actions

Abstract We present the results of our perturbative calculations of the static quark potential, small Wilson loops, the static quark self energy, and the mean link in Landau gauge. These calculations are done for the one loop Symanzik improved gluon action, and the improved staggered quark action.

Progress in automated perturbation theory for heavy quark physics

Abstract We review our perturbative techniques for improved heavy quark actions. A new procedure for computing improvement coefficients is suggested, where the continuum limit of a lattice-regularized theory provides the matching conditions.We also use a gauge-invariant infrared regulator that is well suited to higher-order calculations in lattice gauge theory. We report on preliminary tests of our method, as well as a possible way to reduce systematic errors in these calculations.

Predictions from Lattice QCD

In the past year, we calculated with lattice QCD three quantities that were unknown or poorly known. They are the q{sup 2} dependence of the form factor in semileptonic D {yields} K/{nu} decay, the decay constant of the D meson, and the mass of the B{sub c} meson. In this talk, we summarize these calculations, with emphasis on their (subsequent) confirmation by experiments.

One loop renormalization of fermilab fermions

Abstract We discuss the current status of our automatic perturbation theory program as applied to Fermilab Fermions. We give an overview of our methods, a discussion of tree level matching, and one loop results for the coefficients of the higher dimension kinetic operators.

Highly improved naive and staggered fermions

We present a new action for highly improved staggered fermions. We show that perturbative calculations for the new action are well-behaved where those of the conventional staggered action are badly behaved. We discuss the effects of the new terms in controlling flavor mixing, and discuss the design of operators for the action.

Leptonic decay constants f_Ds and f_D in three flavor lattice QCD

We determine the leptonic decay constants in three flavor unquenched lattice QCD. We use O(a^2)-improved staggered light quarks and O(a)-improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are f_Ds = 263(+5-9)(+/-24) MeV and f_D = 225(+11-13)(+/-21) MeV. In each case, the first reported error is statistical while the is the combined systematic uncertainty.

Leptonic decay constants fDs and fD in three flavor lattice QCD

We determine the leptonic decay constants in three flavor unquenched lattice QCD. We use O(a^2)-improved staggered light quarks and O(a)-improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are f_Ds = 263(+5-9)(+/-24) MeV and f_D = 225(+11-13)(+/-21) MeV. In each case, the first reported error is statistical while the is the combined systematic uncertainty.

B and D meson semileptonic decays in three-flavor lattice QCD

P.B. Mackenzie∗,a, C. Aubinc,d , C. Bernardd , C. DeTare, M. Di Pierro f , Steven Gottliebh, E. Gregory j, U.M. Hellerk, J.E. Hetrickl, A.X. El-Khadram, A.S. Kronfelda, L. Levkovah, F. Marescae, D. Menscherm, M. Nobesn,o, M. Okamotoa, M.B. Oktayq, J. Osborne, D. Renner j, J.N. Simonea, R. Sugarp, D. Toussaint j, H.D. Trottiero E-mail: mackenzie@fnal.gov aFermi National Accelerator Laboratory, Batavia, Illinois 60510, USA cPhysics Department, Columbia University, New York, New York, USA dDepartment of Physics, Washington University, St. Louis, Missouri 63130, USA ePhysics Department, University of Utah, Salt Lake City, Utah 84112, USA f School of Computer Science, Telecommunications and Information Systems, DePaul University,