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arXiv · 2502.06305

The isoscalar non-singlet axial form factor of the nucleon from lattice QCD

Alessandro Barone·Dalibor Djukanovic·Georg von Hippel·Jonna Koponen·Harvey B. Meyer·Konstantin Ottnad·Hartmut Wittig
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Abstract

We present our progress on the computation of the axial form factor of the nucleon with flavour structure $u+d-2s$ from lattice QCD. We employ a set of $N_f=2+1$ CLS ensembles with $O(a)$-improved Wilson fermions and the L\"uscher-Weisz gauge action, with lattice spacings ranging from $0.05\,\text{fm}$ to $0.086\,\text{fm}$ and pion masses spanning between $130\,\text{MeV}$ and $350\,\text{MeV}$. We employ multiple source-sink separations and use the summation method to suppress the contamination from excited states. We use a $z$-expansion on each ensemble to parametrize the $Q^2$-dependence of the form factor and simultaneously fit the available source-sink separations for all $Q^2\leq 0.7 \,{\rm GeV}^2$. We outline our analysis of the stability of the fits varying the ans\"atze and different estimations of the covariance matrix and report on our strategy for a comprehensive determination of the physical form factor.

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Alessandro Barone, Dalibor Djukanovic, Georg von Hippel, Jonna Koponen, Harvey B. Meyer, Konstantin Ottnad, Hartmut Wittig. 2025-02-10. The isoscalar non-singlet axial form factor of the nucleon from lattice QCD. https://arxiv.org/abs/2502.06305

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