B_s → Kℓv form factors with 2+1 flavors

¹ Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
² Department of Physics and Astronomy, Seoul National University, Seoul, South Korea
³ Department of Computational Mathematics, Science and Engineering and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, 48824, USA
⁴ Department of Physics, Washington University, St. Louis, Missouri, 63130, USA
⁵ School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
⁶ Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
⁷ Department of Physics, Syracuse University, Syracuse, New York 13244, USA
⁸ Department of Physics, University of Illinois, Urbana, Illinois 61801, USA
⁹ Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
¹⁰ School of the Art Institute of Chicago, Chicago, Illinois 60603, USA
¹¹ CAFPE and Departamento de Física Teórica y del Cosmos, Universidad de Granada, Granada, Spain
¹² Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA
¹³ American Physical Society, Ridge, New York 11961, USA
¹⁴ Institute for Advanced Study, Technische Universität München, D-85748 Garching, Germany
¹⁵ Department of Physics, University of Colorado, Boulder, CO 80309, USA
¹⁶ RIKEN-BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973, USA
¹⁷ Department of Physics, University of California, Santa Barbara, California 93106, USA
¹⁸ Department of Physics, University of Arizona, Tucson, Arizona 85721, USA

^* Speaker, e-mail: sg@indiana.edu

Published online: 26 March 2018

Abstract

Using the MILC 2+1 flavor asqtad quark action ensembles, we are calculating the form factors f₀ and f₊ for the semileptonic B_s → Kℓv decay. A total of six ensembles with lattice spacing from ≈ 0.12 to 0.06 fm are being used. At the coarsest and finest lattice spacings, the light quark mass m’_l is one-tenth the strange quark mass m’_s. At the intermediate lattice spacing, the ratio m’_l/m’_s ranges from 0.05 to 0.2. The valence b quark is treated using the Sheikholeslami-Wohlert Wilson-clover action with the Fermilab interpretation. The other valence quarks use the asqtad action. When combined with (future) measurements from the LHCb and Belle II experiments, these calculations will provide an alternate determination of the CKM matrix element |V_ub|.