We use lattice QCD to calculate the form factors f+(q2) and f0(q2) for the semileptonic decay Bs→Kℓν. Our calculation uses six MILC asqtad 2+1 flavor gauge-field ensembles with three lattice spacings. At the smallest and largest lattice spacing the light-quark sea mass is set to 1/10 the strange-quark mass. At the intermediate lattice spacing, we use four values for the light-quark sea mass ranging from 1/5 to 1/20 of the strange-quark mass. We use the asqtad improved staggered action for the light valence quarks, and the clover action with the Fermilab interpolation for the heavy valence bottom quark. We use SU(2) hard-kaon heavy-meson rooted staggered chiral perturbation theory to take the chiral-continuum limit. A functional z expansion is used to extend the form factors to the full kinematic range. We present predictions for the differential decay rate for both Bs→Kμν and Bs→Kτν. We also present results for the forward-backward asymmetry, the lepton polarization asymmetry, ratios of the scalar and vector form factors for the decays Bs→Kℓν and Bs→Dsℓν. Our results, together with future experimental measurements, can be used to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |$$V_{ub}$$|.
Bazavov, A., Bernard, C., DeTar, C., Du, Daping, El-Khadra, A. X., Freeland, E. D., Gámiz, E., Gelzer, Z., Gottlieb, Steven, Heller, U. M., Kronfeld, A. S., Laiho, J., Liu, Yuzhi, Mackenzie, P. B., Meurice, Y., Neil, E. T., Simone, J. N., Sugar, R., ... Zhou, Ran (2019). <math display='inline'> <mrow> <msub> <mrow> <mi>B</mi> </mrow> <mrow> <mi>s</mi> </mrow> </msub> <mo stretchy='false'>→</mo> <mi>K</mi> <mo>ℓ</mo> <mi>ν</mi> </mrow> </math> decay from lattice QCD. Physical Review. D., 100(3). https://doi.org/10.1103/PhysRevD.100.034501
@article{osti_1546825,
author = {Bazavov, A. and Bernard, C. and DeTar, C. and Du, Daping and El-Khadra, A. X. and Freeland, E. D. and Gámiz, E. and Gelzer, Z. and Gottlieb, Steven and Heller, U. M. and others},
title = {<math display='inline'>
<mrow>
<msub>
<mrow>
<mi>B</mi>
</mrow>
<mrow>
<mi>s</mi>
</mrow>
</msub>
<mo stretchy='false'>→</mo>
<mi>K</mi>
<mo>ℓ</mo>
<mi>ν</mi>
</mrow>
</math>
decay from lattice QCD},
annote = {We use lattice QCD to calculate the form factors f+(q2) and f0(q2) for the semileptonic decay Bs→Kℓν. Our calculation uses six MILC asqtad 2+1 flavor gauge-field ensembles with three lattice spacings. At the smallest and largest lattice spacing the light-quark sea mass is set to 1/10 the strange-quark mass. At the intermediate lattice spacing, we use four values for the light-quark sea mass ranging from 1/5 to 1/20 of the strange-quark mass. We use the asqtad improved staggered action for the light valence quarks, and the clover action with the Fermilab interpolation for the heavy valence bottom quark. We use SU(2) hard-kaon heavy-meson rooted staggered chiral perturbation theory to take the chiral-continuum limit. A functional z expansion is used to extend the form factors to the full kinematic range. We present predictions for the differential decay rate for both Bs→Kμν and Bs→Kτν. We also present results for the forward-backward asymmetry, the lepton polarization asymmetry, ratios of the scalar and vector form factors for the decays Bs→Kℓν and Bs→Dsℓν. Our results, together with future experimental measurements, can be used to determine the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element |$V_{ub}$|.},
doi = {10.1103/PhysRevD.100.034501},
url = {https://www.osti.gov/biblio/1546825},
journal = {Physical Review. D.},
issn = {ISSN 2470-0010},
number = {3},
volume = {100},
place = {United States},
publisher = {American Physical Society (APS)},
year = {2019},
month = {08}}
APS, New York; Arizona U.; Colorado U.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Granada U., Theor. Phys. Astrophys.; Illinois U., Urbana; Indiana U.; Iowa U.; Michigan State U.; RIKEN BNL; Sch. Art Inst. of Chicago; Syracuse U.; Syracuse Univ., NY (United States); TUM-IAS, Munich; Univ. of Colorado, Boulder, CO (United States); Utah U.; Washington U., St. Louis
Sponsoring Organization:
US Department of Energy; USDOE Office of Science (SC), High Energy Physics (HEP)