Colquhoun, B. , Dowdall, R. J., Koponen, J., Davies, C. T. H. and Lepage, G. P. (2016) B→πℓν at zero recoil from lattice QCD with physical u/d quarks. Physical Review D, 93, 034502. (doi: 10.1103/PhysRevD.93.034502)
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Abstract
The exclusive semileptonic decay B→πℓν is a key process for the determination of the Cabibbo-Kobayashi-Maskawa matrix element Vub from the comparison of experimental rates as a function of q2 with theoretically determined form factors. The sensitivity of the form factors to the u/d quark mass has meant significant systematic uncertainties in lattice QCD calculations at unphysically heavy pion masses. Here we give the first lattice QCD calculations of this process for u/d quark masses going down to their physical values, calculating the f0 form factor at zero recoil to 3\%. We are able to resolve a long-standing controversy by showing that the soft-pion theorem result f0(q2max)=fB/fπ does hold as mπ→0. We use the Highly Improved Staggered Quark formalism for the light quarks and show that staggered chiral perturbation theory for the mπ dependence is almost identical to continuum chiral perturbation theory for f0, fB and fπ. We also give results for other processes such as Bs→Kℓν.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Koponen, Dr Jonna and Colquhoun, Dr Brian and Dowdall, Dr Rachel and Davies, Professor Christine |
Authors: | Colquhoun, B., Dowdall, R. J., Koponen, J., Davies, C. T. H., and Lepage, G. P. |
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 © 2016 The Authors |
First Published: | First published in Physical Review D 93:034502 |
Publisher Policy: | Reproduced under a Creative Commons License |
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