|Vub| from B→πℓν decays and (2+1)-flavor lattice QCD

Bailey, J. A. et al. (2015) |Vub| from B→πℓν decays and (2+1)-flavor lattice QCD. Physical Review D, 92(1), 014024. (doi: 10.1103/PhysRevD.92.014024)

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Abstract

We present a lattice-QCD calculation of the B→πℓν semileptonic form factors and a new determination of the CKM matrix element |Vub|. We use the MILC asqtad (2+1)-flavor lattice configurations at four lattice spacings and light-quark masses down to 1/20 of the physical strange-quark mass. We extrapolate the lattice form factors to the continuum using staggered chiral perturbation theory in the hard-pion and SU(2) limits. We employ a model-independent z parametrization to extrapolate our lattice form factors from large-recoil momentum to the full kinematic range. We introduce a new functional method to propagate information from the chiral-continuum extrapolation to the z expansion. We present our results together with a complete systematic error budget, including a covariance matrix to enable the combination of our form factors with other lattice-QCD and experimental results. To obtain |Vub|, we simultaneously fit the experimental data for the B→πℓν differential decay rate obtained by the BABAR and Belle collaborations together with our lattice form-factor results. We find |Vub|=(3.72±0.16)×10−3, where the error is from the combined fit to lattice plus experiments and includes all sources of uncertainty. Our form-factor results bring the QCD error on |Vub| to the same level as the experimental error. We also provide results for the B→πℓν vector and scalar form factors obtained from the combined lattice and experiment fit, which are more precisely determined than from our lattice-QCD calculation alone. These results can be used in other phenomenological applications and to test other approaches to QCD.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Bouchard, Dr Chris and DeTar, Professor Carleton and Foley, Dr Justin
Authors: Bailey, J. A., Bazavov, A., Bernard, C., Bouchard, C.M., DeTar, C., Du, D., El-Khadra, A.X., Foley, J., Freeland, E.D., Gámiz, E., Gottlieb, S., Heller, U.M., Komijani, J., Kronfeld, A.S., Laiho, J., Levkova, L., Liu, Y., Mackenzie, P.B., Meurice, Y., Neil, E., Qiu, S.-W., Simone, J.N., Sugar, R., Toussaint, D., Van de Water, R.S., and Zhou, R.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review D
Publisher:American Physical Society
ISSN:1550-7998
ISSN (Online):1550-2368
Copyright Holders:Copyright © 2015 American Physical Society
First Published:First published in Physical Review D 92(1): 014024
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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