English

Nucleon axial, tensor, and scalar charges and $\sigma$-terms in lattice QCD

High Energy Physics - Lattice 2025-02-11 v1 High Energy Physics - Experiment High Energy Physics - Phenomenology Nuclear Theory

Abstract

We determine the nucleon axial, scalar and tensor charges at the continuum limit by analyzing three Nf=2+1+1N_f=2+1+1 twisted mass fermion ensembles with all quark masses tuned to approximately their physical values. We include all contributions from valence and sea quarks. We use the Akaike Information Criterion to evaluate systematic errors due to excited states and the continuum extrapolation. For the nucleon isovector axial charge we find gAud=1.250(24)g_A^{u-d}=1.250(24), in agreement with the experimental value. We compute the axial, tensor and scalar charges for each quark flavor. The axial charge provides crucial information on the intrinsic spin carried by quark in the nucleon and the the latter two provide input for experimental searches of physics beyond the standard model. Moreover, we extract the nucleon σ\sigma-terms and find σπN=41.9(8.1)\sigma_{\pi N}=41.9(8.1) MeV, for the strange σs=30(17)\sigma_{s}=30(17) MeV and for the charm σc=82(29)\sigma_{c}=82(29) MeV. We also present preliminary results on the isovector quantities using a fourth ensemble at smaller lattice spacing.

Cite

@article{arxiv.2502.05274,
  title  = {Nucleon axial, tensor, and scalar charges and $\sigma$-terms in lattice QCD},
  author = {Constantia Alexandrou and Simone Bacchio and Jacob Finkenrath and Christos Iona and Giannis Koutsou and Yan Li and Gregoris Spanoudes},
  journal= {arXiv preprint arXiv:2502.05274},
  year   = {2025}
}

Comments

11 pages, 4 figures, 41th International Symposium on Lattice Field Theory - Lattice2024