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Title: A percent-level determination of the nucleon axial coupling from Quantum Chromodynamics

Here, the axial coupling of the nucleon, g A, is the strength of its coupling to the weak axial current of the Standard Model, much as the electric charge is the strength of the coupling to the electromagnetic current. This axial coupling dictates, for example, the rate of β-decay of neutrons to protons and the strength of the attractive long-range force between nucleons. Precision tests of the Standard Model in nuclear environments require a quantitative understanding of nuclear physics rooted in Quantum Chromodynamics, a pillar of this theory. The prominence of g A makes it a benchmark quantity to determine from theory, a difficult task as the theory is non-perturbative. Lattice QCD provides a rigorous, non-perturbative definition of the theory which can be numerically implemented. In order to determine g A, the lattice QCD community has identified two challenges that must be overcome to achieve a 2% precision by 2020: the excited state contamination must be controlled, and the statistical precision must be markedly improved. Here we report a calculation of g A QCD =1.271 ± 0.013, using an unconventional method11 that overcomes these challenges.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [1] ;  [11] ;  [12] ;  [13]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States); Univ. of North Carolina, Chapel Hill, NC (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Forschungszentrum Julich, Julich (Germany); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Univ. of Liverpool, Liverpool (United Kingdom)
  6. College of William and Mary, Williamsburg, VA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  7. Rutgers, The State Univ. of New Jersey, Piscataway, NJ (United States); Univ. of Washington, Seattle, WA (United States)
  8. Univ. of Glasgow, Glasgow (United Kingdom); College of William and Mary, Williamsburg, VA (United States)
  9. NVIDIA Corp., Santa Clara, CA (United States)
  10. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  11. College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
  12. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  13. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
RBRC-1283; BNL-203631-2018-JAAM
Journal ID: ISSN 0028--0836
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Nature
Additional Journal Information:
Journal Name: Nature; Journal ID: ISSN 0028--0836
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26); RIKEN
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
OSTI Identifier:
1436461