https://doi.org/10.1051/epjconf/201817501008
Nucleon axial coupling from Lattice QCD
1
Lawrence Berkeley National Laboratory, Berkeley, CA
2
University of California, Berkeley, CA
3
University of North Carolina, Chapel Hill, NC
4
RIKEN-BNL, Brookhaven National Laboratory, Upton, NY
5
Lawrence Livermore National Laboratory, Livermore, CA
6
Forschungszentrum Jülich, Jülich, Germany
7
University of Liverpool, Liverpool, UK
8
The College of William & Mary, Williamsburg, VA
9
Rutgers, Piscataway, NJ
10
University of Glasgow, Glasgow, UK
11
NVIDIA Corporation, Santa Clara, CA
12
Thomas Jefferson National Accelerator Facility, Newport News, VA
* Speaker, e-mail: chiachang@lbl.gov
Published online: 26 March 2018
We present state-of-the-art results from a lattice QCD calculation of the nucleon axial coupling, gA, using Möbius Domain-Wall fermions solved on the dynamical Nf = 2 + 1 + 1 HISQ ensembles after they are smeared using the gradient-flow algorithm. Relevant three-point correlation functions are calculated using a method inspired by the Feynman-Hellmann theorem, and demonstrate significant improvement in signal for fixed stochastic samples. The calculation is performed at five pion masses of mπ ~ {400, 350, 310, 220, 130} MeV, three lattice spacings of a ~ {0.15, 0.12, 0.09} fm, and we do a dedicated volume study with mπL ~ {3.22, 4.29, 5.36}. Control over all relevant sources of systematic uncertainty are demonstrated and quantified. We achieve a preliminary value of gA = 1.285(17), with a relative uncertainty of 1.33%.
© The Authors, published by EDP Sciences, 2018
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (http://creativecommons.org/licenses/by/4.0/).
