Isovector Axial Vector Form Factors of the Nucleon from Lattice QCD with $N_f=2+1$ $\mathcal{O}(a)$-improved Wilson Fermions

Abstract

We present the analysis of isovector axial vector nucleon form factors on a set of $N_f=2+1$ CLS ensembles with $\mathcal{O}(a)$-improved Wilson fermions and Lüscher-Weisz gauge action. The set of ensembles covers a pion mass range of $130-353$MeV with lattice spacings between $0.05$fm and $0.09$fm. In particular, the set includes a $L/a=96$ ensemble at the physical pion mass. For the purpose of the form factor extraction, we employ both the summed operator insertion method (summation method) and explicit two-state fits in order to account for excited-state contributions to the nucleon correlation functions. To describe the $Q^2$-behavior of the form factors, we perform $z$-expansion fits. Finally, we present HBChPT-inspired chiral and continuum extrapolations of the axial charge and radius.

Comments: 10 pages, 3 figures, 1 table. Talk presented at the 38th International Symposium on Lattice Field Theory (Lattice 2021), 26-30 July, 2021, Zoom/Gather@Massachusetts Institute of Technology