11544193
The kaon B-parameter from unquenched mixed action lattice QCD
We present a preliminary calculation of B{sub K} using domain-wall valence quarks and 2+1 flavors of improved staggered sea quarks. Both the size of the residual quark mass, which measures the amount of chiral symmetry breaking, and of the mixed meson splitting Delta{sub mix}, a measure of taste-symmetry breaking, show that discretization effects are under control in our mixed action lattice simulations. We show preliminary data for pseudoscalar meson masses, decay constants and B{sub K}. We discuss general issues associated with the chiral extrapolation of lattice data, and, as an example, present a preliminary chiral and continuum extrapolation of f{sub pi}. The quality of our data shows that the good chiral properties of domain-wall quarks, in combination with the light sea quark masses and multiple lattice spacings available with the MILC staggered configurations, will allow for a precise determination of B{sub K}.
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%.
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
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
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.
35146463
Neutral kaon mixing parameter BK from unquenched mixed-action lattice QCD
We calculate the neutral kaon mixing parameter B_K in unquenched lattice QCD using asqtad-improved staggered sea quarks and domain-wall valence quarks. We use the "2+1" flavor gauge configurations generated by the MILC Collaboration, and simulate with multiple valence and sea quark masses at two lattice spacings of a ~ 0.12 fm and a ~ 0.09 fm. We match the lattice determination of B_K to the continuum value using the nonperturbative method of Rome-Southampton, and extrapolate B_K to the continuum and physical quark masses using mixed action chiral perturbation theory. The "mixed-action" method enables us to control all sources of systematic uncertainty and therefore to precisely determine B_K; we find a value of B_K^{MSbar, NDR}(2 GeV) = 0.527(6)(20), where the first error is statistical and the second is systematic.
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 )%.
122042804
A Model independent determination of the inclusive semileptonic decay fraction of B mesons
Abstract With the ARGUS detector at the e + e - storage ring DORIS II, we have determined decay fraction and electron momentum spectrum of the inclusive decay mode B → eν X. Usinng lepton tags from the second B meson. in 209 000 γ(4 S ) → B B decays, we could determine the spectrum for all electron momenta p e > 0.6 GeV/ c . Including the small extrapolation to p e > 0, we find the model-independent decay fraction B (B → eν X) = (9.6 ± 0.5 ± 0.4)%. Adding D meson tags, our result is (9.7 ± 0.5 ± 0.4)%.
122762023
Measurement of inclusive baryon production inB meson decays
AbstractUsing the ARGUS detector at thee+e− storage ring DORIS II at DESY, we have studiedB meson decays into baryonsp and Λ. From the simultaneous analysis ofp and Λ yields,p
$$\bar p$$
 and Λ
$$\bar p$$
 correlations, and various lepton-baryon and lepton-baryon-antibaryon correlations the inclusive branching ratio is found to be BR (B→baryons)=(6.8±0.5±0.3)%.
17420422
Study ofD0 andD+ decays into final states with two or three kaons
Using the ARGUS detector at thee+e− storage ring DORIS II, we have studied Cabibbo-suppressedD0 decay modes resulting in theK+K−π+π− final state and two-bodyD0 decay modes with a ϕ meson in the final state. TheBR(D0→KS0KS0π+π− was measured for the first time. We also present a measurement of theD+→KS0KS0K+ branching ratio. The values are compared with other experimental results and model predictions.
120865332
Observation of a new charmed baryon
Abstract Using the ARGUS detector at the e + e − storage ring DORIS II at DESY, we have observed a new charmed baryon state in the channel Λ c + π + π − . (All references to a specific charged state also imply the charge conjugate state.) The mass of this state was measured to be (2626.6 ± 0.5 ± 1.5) MeV/ c 2 . The product of the production cross section and branching ratio for this channel was determined to be (11.5 ± 2.5 ± 3.0) pb, and the natural width estimated to be smaller than 3.2 MeV/ c 2 at 90% CL.