$$B \to \pi \ell \nu$$ and $$B_s \to K \ell \nu$$ form factors and $$V_{ub}$$ from 2+1flavor lattice QCD with domainwall light quarks and relativistic heavy quarks
We calculate the form factors for B → πℓν and B _{s} → Kℓν decay in dynamical lattice quantum chromodynamics (QCD) using domainwall light quarks and relativistic bquarks. We use the (2+1)flavor gaugefield ensembles generated by the RBC and UKQCD collaborations with the domainwall fermion action and Iwasaki gauge action. For the bquarks we use the anisotropic clover action with a relativistic heavyquark interpretation. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as M _{π} ≈ 290 MeV. We simultaneously extrapolate our numerical results to the physical lightquark masses and to the continuum and interpolate in the pion/kaon energy using SU(2) “hardpion” chiral perturbation theory for heavylight meson form factors. We provide complete systematic error budgets for the vector and scalar form factors f + (q ^{2}) and f _{0}(q ^{2}) for both B → πℓν and B _{s} → Kℓν at three momenta that span the q ^{2} range accessible in our numerical simulations. Next we extrapolate these results to q ^{2} = 0 using a modelindependent zparametrization based on analyticity and unitarity. We present our final results for f _{+}(q ^{2}) and f _{0}(q ^{2})as the coefficientsmore »
 Authors:

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 Univ. of Southampton, Southampton (United Kingdom)
 Brookhaven National Lab. (BNL), Upton, NY (United States)
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 Boston Univ., Boston, MA (United States)
 Publication Date:
 Report Number(s):
 FERMILABPUB15019T
Journal ID: ISSN 15507998; arXiv eprint number arXiv:1501.05373; TRN: US1600873
 Grant/Contract Number:
 AC0207CH11359
 Type:
 Accepted Manuscript
 Journal Name:
 Physical Review. D, Particles, Fields, Gravitation and Cosmology
 Additional Journal Information:
 Journal Volume: 91; Journal Issue: 7; Journal ID: ISSN 15507998
 Publisher:
 American Physical Society (APS)
 Research Org:
 Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
 Sponsoring Org:
 USDOE Office of Science (SC), High Energy Physics (HEP) (SC25)
 Contributing Orgs:
 RBC Collaboration; UKQCD Collaboration
 Country of Publication:
 United States
 Language:
 English
 Subject:
 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
 OSTI Identifier:
 1221234
 Alternate Identifier(s):
 OSTI ID: 1180799
Flynn, J. M., Izubuchi, T., Kawanai, T., Lehner, C., Soni, A., Van de Water, R. S., and Witzel, O.. $B \to \pi \ell \nu$ and $B_s \to K \ell \nu$ form factors and $V_{ub}$ from 2+1flavor lattice QCD with domainwall light quarks and relativistic heavy quarks. United States: N. p.,
Web. doi:10.1103/PhysRevD.91.074510.
Flynn, J. M., Izubuchi, T., Kawanai, T., Lehner, C., Soni, A., Van de Water, R. S., & Witzel, O.. $B \to \pi \ell \nu$ and $B_s \to K \ell \nu$ form factors and $V_{ub}$ from 2+1flavor lattice QCD with domainwall light quarks and relativistic heavy quarks. United States. doi:10.1103/PhysRevD.91.074510.
Flynn, J. M., Izubuchi, T., Kawanai, T., Lehner, C., Soni, A., Van de Water, R. S., and Witzel, O.. 2015.
"$B \to \pi \ell \nu$ and $B_s \to K \ell \nu$ form factors and $V_{ub}$ from 2+1flavor lattice QCD with domainwall light quarks and relativistic heavy quarks". United States.
doi:10.1103/PhysRevD.91.074510. https://www.osti.gov/servlets/purl/1221234.
@article{osti_1221234,
title = {$B \to \pi \ell \nu$ and $B_s \to K \ell \nu$ form factors and $V_{ub}$ from 2+1flavor lattice QCD with domainwall light quarks and relativistic heavy quarks},
author = {Flynn, J. M. and Izubuchi, T. and Kawanai, T. and Lehner, C. and Soni, A. and Van de Water, R. S. and Witzel, O.},
abstractNote = {We calculate the form factors for B → πℓν and Bs → Kℓν decay in dynamical lattice quantum chromodynamics (QCD) using domainwall light quarks and relativistic bquarks. We use the (2+1)flavor gaugefield ensembles generated by the RBC and UKQCD collaborations with the domainwall fermion action and Iwasaki gauge action. For the bquarks we use the anisotropic clover action with a relativistic heavyquark interpretation. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as Mπ ≈ 290 MeV. We simultaneously extrapolate our numerical results to the physical lightquark masses and to the continuum and interpolate in the pion/kaon energy using SU(2) “hardpion” chiral perturbation theory for heavylight meson form factors. We provide complete systematic error budgets for the vector and scalar form factors f + (q2) and f0(q2) for both B → πℓν and Bs → Kℓν at three momenta that span the q2 range accessible in our numerical simulations. Next we extrapolate these results to q2 = 0 using a modelindependent zparametrization based on analyticity and unitarity. We present our final results for f+(q2) and f0(q2)as the coefficients of the series in z and the matrix of correlations between them; this provides a parametrization of the form factors valid over the entire allowed kinematic range. Our results agree with other threeflavor latticeQCD determinations using staggered light quarks, and have comparable precision, thereby providing important independent crosschecks. Both B → πℓν and Bs → Kℓν decays enable determinations of the CabibboKobayashiMaskawa matrix element Vub. Furthermore, we perform a combined zfit of our numerical B → πℓν formfactor data with the experimental measurements of the branching fraction from BABAR and Belle leaving the relative normalization as a free parameter; we obtain Vub = 3.61(32)×103, where the error includes statistical and all systematic uncertainties. The same approach can be applied to the decay Bs → Kℓν to provide an alternative determination of Vub once the process has been measured experimentally. In anticipation of future experimental measurements, we make predictions for B → πℓν and Bs → Kℓν differential branching fractions and forwardbackward asymmetries in the Standard Model.},
doi = {10.1103/PhysRevD.91.074510},
journal = {Physical Review. D, Particles, Fields, Gravitation and Cosmology},
number = 7,
volume = 91,
place = {United States},
year = {2015},
month = {4}
}