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arXiv · 1205.7013

Neutral B-meson mixing from three-flavor lattice QCD: Determination of the SU(3)-breaking ratio ξ

A. Bazavov·C. Bernard·C. M. Bouchard·C. DeTar·M. Di Pierro·A. X. El-Khadra·R. T. Evans·E. D. Freeland·E. Gamiz·Steven Gottlieb·U. M. Heller·J. E. Hetrick·R. Jain·A. S. Kronfeld·J. Laiho·L. Levkova·P. B. Mackenzie·E. T. Neil·M. B. Oktay·J. N. Simone·R. Sugar·D. Toussaint·R. S. Van de Water
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Abstract

We study SU(3)-breaking effects in the neutral B_d-\bar B_d and B_s-\bar B_s systems with unquenched N_f=2+1 lattice QCD. We calculate the relevant matrix elements on the MILC collaboration's gauge configurations with asqtad-improved staggered sea quarks. For the valence light-quarks (u, d, and s) we use the asqtad action, while for b quarks we use the Fermilab action. We obtain ξ=f_{B_s}\sqrt{B_{B_s}}/f_{B_d}\sqrt{B_{B_d}}=1.268+-0.063. We also present results for the ratio of bag parameters B_{B_s}/B_{B_d} and the ratio of CKM matrix elements |V_{td}|/|V_{ts}|. Although we focus on the calculation of ξ, the strategy and techniques described here will be employed in future extended studies of the B mixing parameters ΔM_{d,s} and ΔΓ_{d,s} in the Standard Model and beyond.

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A. Bazavov, C. Bernard, C. M. Bouchard, C. DeTar, M. Di Pierro, A. X. El-Khadra, R. T. Evans, E. D. Freeland, E. Gamiz, Steven Gottlieb, U. M. Heller, J. E. Hetrick, R. Jain, A. S. Kronfeld, J. Laiho, L. Levkova, P. B. Mackenzie, E. T. Neil, M. B. Oktay, J. N. Simone, R. Sugar, D. Toussaint, R. S. Van de Water. 2012-05-31. Neutral B-meson mixing from three-flavor lattice QCD: Determination of the SU(3)-breaking ratio ξ. https://doi.org/10.1103/physrevd.86.034503

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