We compute the B <→> πlv semileptonic form factors and update the determination of the CKM matrix element |Vub|. We use the MILC asqtad ensembles with Nf = 2 + 1 sea quarks at four different lattice spacings in the range a ≈ 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 q2 to the full kinematic range using a functional zparameterization. The extrapolation is combined with the experimental measurements of the partial branching fraction to extract |Vub|. Our preliminary result is |Vub| = (3.72±0.14) x 10-3, where the error reflects both the lattice and experimental uncertainties, which are now on par with each other.
|Journal||Proceedings of Science|
|Publication status||Published - 2014|
|Event||32nd International Symposium on Lattice Field Theory, LATTICE 2014 - New York, United States|
Duration: 2014 Jun 23 → 2014 Jun 28
Bibliographical noteFunding Information:
∗Present address: Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 †Speaker. ‡Email: firstname.lastname@example.org §Present address: Laboratory of Biological Modeling, NIDDK, NIH, Bethesda, Maryland, USA ¶Brookhaven National Lab is operated by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the U.S. De-partment of Energy. ‖Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S.
This work was supported by the U.S. Department of Energy and National Science Foundation, by the URA Visiting Scholars’ program, and by the MINECO, Junta de Andalucia, the European Commission, the German Excellence Initiative, the European Union Seventh Framework Programme, and the European Union’s Marie Curie COFUND program. Computation for this work was done at the Argonne Leadership Computing Facility (ALCF), the National Center for Atmospheric Research (UCAR), the National Energy Resources Supercomputing Center (NERSC), the National Institute for Computational Sciences (NICS), the Texas Advanced Computing Center (TACC), and the USQCD facilities at Fermilab, under grants from the NSF and DOE.
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