11830406
The Kaon B-parameter in Mixed Action Chiral Perturbation Theory
We calculate the kaon B-parameter, BK , in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We find that the resulting expression is similar to that in the continuum, and in fact has only two additional unknown parameters. At one-loop order, taste-symmetry violations in the staggered sea sector only contribute to flavor-disconnected diagrams by generating an O(a2) shift to the masses of taste-singlet sea-sea mesons. Lattice discretization errors also give rise to an analytic term which shifts the tree-level value of BK by an amount of O(a 2). This term, however, is not strictly due to taste-breaking, and is therefore also present in the expression for BK for pure G-W lattice fermions. We also present a numerical study of the mixed BK expression in order to demonstrate that both discretization errors and finite volume effects are small and under control on the MILC improved
118595631
Charm semileptonic decays and|Vcs(d) from heavy clover quarks and 2+1 flavor asqtad staggered ensembles
By combining experimentally measured partial branching fractions for the semileptonic decays D→Klν and D→ πlν with lattice calculations of the form factors f D→K + (q2) and f D→π + (q2), one can extract the CKM matrix elements |Vcs| and |Vcd |. We are calculating the form factors by using Fermilab charm and asqtad staggered light and strange quarks on 2+1 flavor asqtad staggered ensembles generated by the MILC Collaboration. We vary the light valence quark masses from 0.4ms to 0.05ms (ms is the strange sea-quark mass), and the lattice spacings, from about 0.12 fm to about 0.045 fm. We extrapolate to the physical light-quark mass and the continuum limit using heavy-light meson staggered chiral perturbation theory about the SU(2) and SU(3) limits, compare the resulting (preliminary) form factor shapes with experiment, and discuss our errors.
15857007
Unitarity and the heavy quark expansion in the determination of semileptonic form factors
We discuss prospects for improving the q 2 extrapolation of the B → πlν form factors with model-independent constraints based on unitarity and heavy quark power-counting. As an illustration, we apply the method to preliminary results of calculations of the form factors, which we generated using the MILC gauge configurations and the Fermilab action for the heavy b-quark. Unitarity, the heavy quark expansion, and semileptonic form factors Ruth S. Van de Water
119241694
Matrix Elements for D- and B-Mixing from 2+1 Flavor Lattice QCD
C.C. Chang∗ a f , C. Bernard b, C.M. Bouchard c, A.X. El-Khadra a f , E.D. Freeland d, E. Gamiz e, A.S. Kronfeld f , J. Laiho g, R.S. van de Water f aPhysics Department, University of Illinois, Urbana, IL 61801, USA bDepartment of Physics, Washington University, St. Louis, MO 63130, USA cDepartment of Physics, The Ohio State University, Columbus, OH 43210, USA dLiberal Arts Department, The School of the Art Institute of Chicago, Chicago, IL 60603, USA eCAFPE and Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, E-18002 Granada, Spain fTheoretical Physics Department, Fermi National Accelerator Laboratory†, Batavia, IL 60510, USA gSUPA, Department of Physics and Astronomy, University of Glasgow, Glasgow, G12-8QQ, United Kingdom
118670651
$D$ semileptonic form factors and $|V_{cs(d)}|$ from 2+1 flavor lattice QCD
The measured partial widths of the semileptonic decays D {yields} K{ell}{nu} and D {yields} {pi}{ell}{nu} can be combined with the form factors calculated on the lattice to extract the CKM matrix elements |V{sub cs}| and |V{sub cd}|. The lattice calculations can be checked by comparing the form factor shapes from the lattice and experiment. We have generated a sizable data set by using heavy clover quarks with the Fermilab interpretation for charm and asqtad staggered light quarks on 2+1 flavor MILC ensembles with lattice spacings of approximately 0.12, 0.09, 0.06, and 0.045 fm. Preliminary fits to staggered chiral perturbation theory suggest that we can reduce the uncertainties in the form factors at q{sup 2} = 0 to below 5%.
7429466
Light pseudoscalar meson masses and decay constants from mixed action lattice QCD
We calculate the light pseudoscalar decay constants, f_pi and f_K, and their ratio using domain wall valence quarks and 2+1 flavors of dynamical staggered quarks. Use of the MILC gauge configurations allows us to simulate at several sea quark masses and spatial volumes, and with two lattice spacings. We study how well our numerical lattice data for light decay constants and meson masses is described by next-to-leading order SU(3) mixed action chiral perturbation theory and explain our strategy for the chiral and continuum extrapolation. Combining our result for f_K/f_pi with experimental measurements of pion and kaon leptonic decays allows a model-independent determination of |V_us|/|V_ud|; we find a preliminary value of |V_us|/|V_ud| = 0.2315(45)(7).
123971124
Latest Oscillation Results from SNO
The Sudbury Neutrino Observatory has been successfully taking quality neutrino data for over two years now. This paper reports on analysis of the solar charge current and elastic scattering neutrino fluxes from the first year of pure D2O running. Combined with the SuperK elastic scattering flux, there is strong evidence that solar neutrinos are oscillating, and that predictions of the standard solar model are in good agreement with data.
122603059
Search for rare B decays
Abstract Using the ARGUS detector at the e + e − storage ring DORIS II at DESY, we have searched for decays b → s gluon through full reconstruction of a whole event. Two B B decays were found with one of B meson decaying into a final state without charmed particles. We also obtained an upper limit of Br (B + → τ + ν τ ) of 1.04% at 90% CL .
209962993
Search for neutrinoless tau decays
122313771
Evidence for W exchange in charmed baryon decays
Using the detector ARGUS at the e+e− storage ring DORIS II at DESY, we have observed the decays Λc+ → Ξ−K+π+ and Λc+ → Ξ∗0K+ and obtained evidence for the decay Ξc0 → ΛKs0. All three of these decays are of interest as they provide information about W-exchange processes. The products of cross sections and branching ratios for Λc+ → Ξ−K+π+ and Λc+ → Ξ∗0K+ are (1.7±0.3±0.3) pb and (0.6±0.2±0.1) pb, respectively, which implies that (35±17) % of the Ξ−K+π+ final state is generated through a two-body decay via intermediate W-exchange. The product of production cross section and branching ratio for Ξc0 → Λ Ks0 is (2.1 ± 1.0 ± 0.6) pb.
120707119
A measurement of the inclusive semileptonic decay fraction of charmed hadrons
Abstract Using the ARGUS detector at the DORIS-II storage ring at DESY, we have measured the inclusive semileptonic branching ratio of charmed hadrons produced in e + e − annihilition at =10 GeV to be BR(c→ev e X)=(9.8±0.9± 0.5 0.6 )% and BR(c→ μv μ X)=(8.6±1.7± 0.7 0.8 )%.