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B → π`ν semileptonic form factors from unquenched lattice QCD and determination of |Vub|
Conference proceeding   Open access

B → π`ν semileptonic form factors from unquenched lattice QCD and determination of |Vub|

J. A Bailey, A Bazavov, C Bernard, C Bouchard, C DeTar, D Du, A. X El-Khadra, J Foley, E. D Freeland, E Gamiz, …
Proceedings of The 32nd International Symposium on Lattice Field Theory, Vol.214, p.385
The 32nd International Symposium on Lattice Field Theory, LATTICE2014 (Columbia University New York, NY, 06/23/2014–06/28/2014)
05/21/2015
DOI: 10.22323/1.214.0385
url
https://doi.org/10.22323/1.214.0385View
Published (Version of record) Open Access

Abstract

PoS(LATTICE 2014)385 We compute the $B\to\pi\ell\nu$ semileptonic form factors and update the determination of the CKM matrix element $|V_{ub}|$. We use the MILC asqtad ensembles with $N_f=2+1$ sea quarks at four different lattice spacings in the range $a \approx 0.045$~fm to $0.12$~fm. The lattice form factors are extrapolated to the continuum limit using SU(2) staggered chiral perturbation theory in the hard pion limit, followed by an extrapolation in $q^2$ to the full kinematic range using a functional $z$-parameterization. The extrapolation is combined with the experimental measurements of the partial branching fraction to extract $|V_{ub}|$. Our preliminary result is $|V_{ub}|=(3.72\pm 0.14)\times 10^{-3}$, where the error reflects both the lattice and experimental uncertainties, which are now on par with each other.
 Physics - High Energy Physics - Lattice

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