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Title: Axial, scalar, and tensor charges of the nucleon from 2+1+1-flavor lattice QCD

Here, we present results for the isovector axial, scalar, and tensor charges gu–dA, gu–dS, and gu–dT of the nucleon needed to probe the Standard Model and novel physics. The axial charge is a fundamental parameter describing the weak interactions of nucleons. The scalar and tensor charges probe novel interactions at the TeV scale in neutron and nuclear β-decays, and the flavor-diagonal tensor charges guT, gdT, and gsT are needed to quantify the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The lattice-QCD calculations were done using nine ensembles of gauge configurations generated by the MILC Collaboration using the highly improved staggered quarks action with 2+1+1 dynamical flavors. These ensembles span three lattice spacings a ≈ 0.06,0.09, and 0.12 fm and light-quark masses corresponding to the pion masses Mπ ≈ 135, 225, and 315 MeV. High-statistics estimates on five ensembles using the all-mode-averaging method allow us to quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, lattice volume, and light-quark masses for the connected contributions. Our final estimates, in the ¯MS scheme at 2 GeV, of the isovector charges are gu–dA = 1.195(33)(20), gu–dS = 0.97(12)(6), and gu–dT = 0.987(51)(20). The first errormore » includes statistical and all systematic uncertainties except that due to the extrapolation Ansatz, which is given by the second error estimate. Combining our estimate for gu–dS with the difference of light quarks masses (md–mu)QCD = 2.67(35) MeV given by the Flavor Lattice Average Group, we obtain (MN – MP)QCD = 2.59(49) MeV. Estimates of the connected part of the flavor-diagonal tensor charges of the proton are guT = 0.792(42) and gdT = –0.194(14). Combining our new estimates with precision low-energy experiments, we present updated constraints on novel scalar and tensor interactions, εS,T, at the TeV scale.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ; ORCiD logo [1] ;  [3] ; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Univ. of Washington, Seattle, WA (United States)
  3. Univ. of California, Berkeley, CA (United States)
Publication Date:
Report Number(s):
LA-UR-16-20522
Journal ID: ISSN 2470-0010; PRVDAQ
Grant/Contract Number:
AC52-06NA25396; KA-1401020; AC02-05CH11231; FG02-97ER4014
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 94; Journal Issue: 5; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
Precision Neutron Decay Matrix Elements (PNDME) Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; atomic and nuclear physics
OSTI Identifier:
1343698
Alternate Identifier(s):
OSTI ID: 1328532