Nucleon axial coupling from Lattice QCD


We present state-of-the-art results from a lattice QCD calculation of the nucleon axial coupling, $g_A$, using M$$"obius Domain-Wall fermions solved on the dynamical $N_f = 2 + 1 + 1$ HISQ ensembles after they are smeared using the gradient-flow algorithm. Relevant three-point correlation functions are calculated using a method inspired by the Feynman-Hellmann theorem, and demonstrate significant improvement in signal for fixed stochastic samples. The calculation is performed at five pion masses of $m_\pi\sim \400, 350, 310, 220, 130$̃MeV, three lattice spacings of $a\sim\0.15, 0.12, 0.09$̃fm, and we do a dedicated volume study with $m_\pi L\sim\3.22, 4.29, 5.36$. Control over all relevant sources of systematic uncertainty are demonstrated and quantified. We achieve a preliminary value of $g_A = 1.285(17)$, with a relative uncertainty of 1.33$$%.

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Enrico Rinaldi
Enrico Rinaldi
Research Scientist

My research interests include artificial intelligence and quantum computing applied to particle physics and quantum many-body systems.