Semileptonic form factor ratio B_s->D_s/B->D and its application to BR(B^0_s->\mu^+\mu^-)

We present a (2+1)-flavor lattice QCD calculation of the form factor ratio between the semileptonic decays $\bar{B}^0_s \to D^+_sl^-\bar{\nu}$ and $\bar{B}^0 \to D^+l^-\bar{\nu}$. This ratio is an important theoretical input to the hadronic determination of the $B$ meson fragmentation fraction ratio $f_s/f_d$ which enters in the measurement of $\mathrm{BR}(B^0_s\to \mu^+\mu^-)$. Small lattice spacings and high statistics enable us to simulate the decays with a dynamic final $D$ meson of small momentum and reliably extract the hadronic matrix elements at nonzero recoil. We report our preliminary result for the form factor ratio at the corresponding momentum transfer of the two decays $f_0^{(s)}(M^2_\pi)/f_0^{(d)}(M^2_K)$.Comment: 7 pages, 6 figures. Talk presented at The XXIX International Symposium on Lattice Field Theory - Lattice 2011, July 10-16, 2011, Squaw Valley, Lake Tahoe, California; Minor errors corrected, references and graphs update

Semileptonic B to D decays at nonzero recoil with 2+1 flavors of improved staggered quarks. An update

The Fermilab Lattice and MILC collaborations are completing a comprehensive program of heavy-light physics on MILC (2+1)-flavor asqtad ensembles with lattice spacings as small as 0.045 fm and light-to-strange-quark mass ratios as low as 1/20. We use the Fermilab interpretation of the clover action for heavy valence quarks and the asqtad action for the light valence quarks. The central goal of the program is to provide ever more exacting tests of the unitarity of the CKM matrix. We present preliminary results for one part of the program, namely the analysis of the semileptonic decay B -> D l nu at nonzero recoil.Comment: 7 pp, 7 figs, Lattice 201

Semileptonic B to D decays at nonzero recoil with 2+1 flavors of improved staggered quarks

The Fermilab Lattice-MILC collaboration is completing a comprehensive program of heavy-light physics on the MILC (2+1)-flavor asqtad ensembles with lattice spacings as small as 0.045 fm and light-to-strange-quark mass ratios as low as 1/20. We use the Fermilab interpretation of the clover action for heavy valence quarks and the asqtad action for light valence quarks. The central goal of the program is to provide ever more exacting tests of the unitarity of the CKM matrix. We give a progress report on one part of the program, namely the analysis of the semileptonic decay B to D at both zero and nonzero recoil. Although final results are not presented, we discuss improvements in the analysis methods, the statistical errors, and the parameter coverage that we expect will lead to a significant reduction in the final error for |V_cb| from this decay channel.Comment: 7 pages, 3 figures, LATTICE 2011 conferenc

The Dwarf Galaxy Population at z ∼ 0.7: A Catalog of Emission Lines and Redshifts from Deep Keck Observations

We present a catalog of spectroscopically measured redshifts over $0 < z < 2$ and emission line fluxes for 1440 galaxies. The majority ($\sim$65\%) of the galaxies come from the HALO7D survey, with the remainder from the DEEPwinds program. This catalog includes redshifts for 646 dwarf galaxies with $\log(M_{\star}/M_{\odot}) < 9.5$. 810 catalog galaxies did not have previously published spectroscopic redshifts, including 454 dwarf galaxies. HALO7D used the DEIMOS spectrograph on the Keck II telescope to take very deep (up to 32 hours exposure, with a median of $\sim$7 hours) optical spectroscopy in the COSMOS, EGS, GOODS-North, and GOODS-South CANDELS fields, and in some areas outside CANDELS. We compare our redshift results to existing spectroscopic and photometric redshifts in these fields, finding only a 1\% rate of discrepancy with other spectroscopic redshifts. We measure a small increase in median photometric redshift error (from 1.0\% to 1.3\%) and catastrophic outlier rate (from 3.5\% to 8\%) with decreasing stellar mass. We obtained successful redshift fits for 75\% of massive galaxies, and demonstrate a similar 70-75\% successful redshift measurement rate in $8.5 < \log(M_{\star}/M_{\odot}) < 9.5$ galaxies, suggesting similar survey sensitivity in this low-mass range. We describe the redshift, mass, and color-magnitude distributions of the catalog galaxies, finding HALO7D galaxies representative of CANDELS galaxies up to \textit{i}-band magnitudes of 25. The catalogs presented will enable studies of star formation (SF), the mass-metallicity relation, SF-morphology relations, and other properties of the $z\sim0.7$ dwarf galaxy population.Comment: 23 pages, 19 Figures, updated to version accepted by ApJ

Lattice QCD and Particle Physics

Contribution from the USQCD Collaboration to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021).Comment: 27 pp. main text, 4 pp. appendices, 30 pp. reference

Lattice QCD and Particle Physics

Contribution from the USQCD Collaboration to the Proceedings of the US Community Study on the Future of Particle Physics (Snowmass 2021)