B→πℓν at zero recoil from lattice QCD with physical u/d quarks

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)

113888.pdf - Published Version
Available under License Creative Commons Attribution.



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
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 (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
Related URLs:

University Staff: Request a correction | Enlighten Editors: Update this record

Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
573721Phenomenology from Lattice QCD and Collider PhysicsChristine DaviesScience & Technologies Facilities Council (STFC)ST/J000442/1P&A - PHYSICS & ASTRONOMY
630801Phenomenology from Lattice QCD and collider physicsChristine DaviesScience & Technologies Facilities Council (STFC)ST/L000466/1S&E P&A - PHYSICS & ASTRONOMY