Improved Vcs determination using precise lattice QCD form factors for D → Klν
Improved Vcs determination using precise lattice QCD form factors for D → Klν
We provide a 0.8%-accurate determination of Vcs from combining experimental results for the differential rate of D→K semileptonic decays with precise form factors that we determine from lattice QCD. This is the first time that Vcs has been determined with an accuracy that allows its difference from 1 to be seen. Our lattice QCD calculation uses the highly improved staggered quark (HISQ) action for all valence quarks on gluon field configurations generated by the MILC Collaboration that include the effect of u, d, s, and c HISQ quarks in the sea. We use eight gluon field ensembles with five values of the lattice spacing ranging from 0.15 fm to 0.045 fm and include results with physical u/d quarks for the first time. Our calculated form factors cover the full q2 range of the physical decay process and enable a Standard Model test of the shape of the differential decay rate as well as the determination of Vcs from a correlated weighted average over q2 bins. We obtain|Vcs|=0.9663(53)latt(39)exp(19)ηEW(40)EM, where the uncertainties come from lattice QCD, experiment, short-distance electroweak, and electromagnetic corrections, respectively. This last uncertainty, neglected for D→Kν hitherto, now needs attention if the uncertainty on Vcs is to be reduced further. We also determine Vcs values in good agreement using the measured total branching fraction and the rates extrapolated to q2=0. Our form factors enable tests of lepton flavor universality violation. We find the ratio of branching fractions for D0→K- with μ and e in the final state to be Rμ/e=0.9779(2)latt(50)EM in the Standard Model, with the uncertainty dominated by that from electromagnetic corrections.
Chakraborty, Bipasha
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Parrott, W.G.
ccaa90f3-70b3-42f9-8aac-f61e71cab02e
Bouchard, C.
a5aee64c-92e2-497f-85a9-e0de83e57a7f
Davies, C.T.H.
41024db5-1cf1-42ab-81c0-5862d5a7ef68
Koponen, J.
c9b31cce-939e-4662-b07e-a26d56d589ac
Lepage, G.P.
4d8d525a-d030-49c1-8254-c346734b4648
24 August 2021
Chakraborty, Bipasha
7bc388c0-e36c-47a7-b5f2-a27839178e48
Parrott, W.G.
ccaa90f3-70b3-42f9-8aac-f61e71cab02e
Bouchard, C.
a5aee64c-92e2-497f-85a9-e0de83e57a7f
Davies, C.T.H.
41024db5-1cf1-42ab-81c0-5862d5a7ef68
Koponen, J.
c9b31cce-939e-4662-b07e-a26d56d589ac
Lepage, G.P.
4d8d525a-d030-49c1-8254-c346734b4648
HPQCD Collaboration
(2021)
Improved Vcs determination using precise lattice QCD form factors for D → Klν.
Physical Review D, 104 (3), [034505].
(doi:10.1103/PhysRevD.104.034505).
Abstract
We provide a 0.8%-accurate determination of Vcs from combining experimental results for the differential rate of D→K semileptonic decays with precise form factors that we determine from lattice QCD. This is the first time that Vcs has been determined with an accuracy that allows its difference from 1 to be seen. Our lattice QCD calculation uses the highly improved staggered quark (HISQ) action for all valence quarks on gluon field configurations generated by the MILC Collaboration that include the effect of u, d, s, and c HISQ quarks in the sea. We use eight gluon field ensembles with five values of the lattice spacing ranging from 0.15 fm to 0.045 fm and include results with physical u/d quarks for the first time. Our calculated form factors cover the full q2 range of the physical decay process and enable a Standard Model test of the shape of the differential decay rate as well as the determination of Vcs from a correlated weighted average over q2 bins. We obtain|Vcs|=0.9663(53)latt(39)exp(19)ηEW(40)EM, where the uncertainties come from lattice QCD, experiment, short-distance electroweak, and electromagnetic corrections, respectively. This last uncertainty, neglected for D→Kν hitherto, now needs attention if the uncertainty on Vcs is to be reduced further. We also determine Vcs values in good agreement using the measured total branching fraction and the rates extrapolated to q2=0. Our form factors enable tests of lepton flavor universality violation. We find the ratio of branching fractions for D0→K- with μ and e in the final state to be Rμ/e=0.9779(2)latt(50)EM in the Standard Model, with the uncertainty dominated by that from electromagnetic corrections.
Text
PhysRevD.104.034505
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Accepted/In Press date: 15 July 2021
Published date: 24 August 2021
Identifiers
Local EPrints ID: 491647
URI: http://eprints.soton.ac.uk/id/eprint/491647
ISSN: 2470-0010
PURE UUID: 02366ed7-d7d4-4093-9ed5-fde5ce6bbb43
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Date deposited: 03 Jul 2024 09:32
Last modified: 11 Jul 2024 05:06
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Contributors
Author:
W.G. Parrott
Author:
C. Bouchard
Author:
C.T.H. Davies
Author:
J. Koponen
Author:
G.P. Lepage
Corporate Author: HPQCD Collaboration
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