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Junko Shigemitsu

Publications and source records attributed to Junko Shigemitsu.

47 records · Page 3Linked to original sources
arXiv2003

Progress Calculating Decay Constants with NRQCD and AsqTad Actions

We combine a light AsqTad antiquark with a nonrelativistic heavy quark to compute the decay constants of heavy-light pseudoscalar mesons using the ensemble of 3-flavor gauge field configurations generated by the MILC collaboration. Preliminary results for $f_{B_s}$ and $f_{D_s}$ are given and status of the chiral extrapolation to $f_B$ is reported. We also touch upon results of the perturbative calculation which matches matrix elements in the effective theory to the full theory at 1-loop order.

hep-lat↗
arXiv2003

Heavy-light mesons with staggered light quarks

We demonstrate the viability of improved staggered light quarks in studies of heavy-light systems. Our method for constructing heavy-light operators exploits the close relation between naive and staggered fermions. The new approach is tested on quenched configurations using several staggered actionsn combined with nonrelativistic heavy quarks. The B_s meson kinetic mass, the hyperfine and 1P-1S splittings in B_s, and the decay constant f_{B_s} are calculated and compared to previous quenched lattice studies. An important technical detail, Bayesian curve-fitting, is discussed at length.

hep-lat↗
arXiv2002

B_s Mesons using Staggered Light Quarks

Last year we proposed using staggered fermions as the light quarks, combined with nonrelativistic heavy quarks, in simulations of heavy-light mesons. A first round of tests which focuses on the B_s meson has been completed using quenched lattices, and results are presented here for the kinetic B_s mass, the B_s^* - B_s splitting, and f_{B_s}. The next project, already underway, is to compute the B and B_s decay constants and spectra on the n_f = 2+1 and 3 MILC lattices. We report on progress with one set of these configurations.

hep-lat↗
arXiv2001

Heavy-light physics using NRQCD-staggered actions

One leading source of uncertainty in the lattice computation of semi-leptonic form factors in B decay, and to a lesser extent B meson decay constants, comes from the extrapolation of the light quark mass to the physical up/down mass. This talk presents first explorations of simulating the light quark with staggered fermion actions, which are free of the spurious zero modes that effect Wilson-like Dirac operators and are less costly. Methods for fitting to Euclidean-time NRQCD-staggered meson propagators are discussed, and some preliminary spectrum results are presented.

hep-lat↗
arXiv2000

Can One Study Heavy Meson Semileptonic Decays on Coarse Anisotropic Lattices ?

Exploratory studies of heavy meson semileptonic decays on coarse lattices using Symanzik improved glue, NRQCD heavy and D234 light quarks are discussed. Comparisons are made between calculations on anisotropic and isotropic lattices. We find evidence that having an anisotropy helps in extracting better signals at higher momenta.

hep-lat↗
arXiv2000

One-Loop Self Energy and Renormalization of the Speed of Light for some Anisotropic Improved Quark Actions

One-loop corrections to the fermion rest mass M_1, wave function renormalization Z_2 and speed of light renormalization C_0 are presented for lattice actions that combine improved glue with clover or D234 quark actions and keep the temporal and spatial lattice spacings, a_t and a_s, distinct. We explore a range of values for the anisotropy parameter χ= a_s/a_t and treat both massive and massless fermions.

hep-lat↗
arXiv1997

B Meson Decay Constants Using NRQCD

Recent results for B meson decay constants with NRQCD b-quarks and clover light quarks are discussed. Perturbative matching factors through O($α/M$) are now available and incorporated into the analyses. An O($αa$) improvement term to the heavy-light axial current is identified and included. The slope of $f_{PS}\sqrt{M_{PS}}$ versus $1/M_{PS}$ is significantly reduced by these corrections.

hep-lat↗
arXiv1994

Lattice Gauge Theory: Status Report 1994

We report on recent developments and results from Lattice Gauge Theory. These include determinations of the strong coupling constant $α_s$ and the b-quark mass $M_b$ and an update on the Kaon B parameter $B_K$. Lattice results for heavy meson decay constants and semileptonic B and D meson decay form factors are reviewed. The first attempts to study the Isgur-Wise function and the radiative Penguin decay process, $B \rightarrow K^*\,γ$, on the lattice are discussed. (Review talk presented ICHEP 94, Glasgow, July 1994) OHSTPY-HEP-T-94-016

hep-ph↗