Strangeness of nucleons from $N_f=2+1+1$ lattice QCD

TL;DR

This paper computes the strange electromagnetic form factors of the nucleon using advanced lattice QCD simulations at the physical point, achieving unprecedented precision and eliminating chiral extrapolation uncertainties.

Contribution

First lattice QCD calculation of strange nucleon form factors at the continuum limit with physical quark masses, reducing systematic uncertainties.

Findings

Strange electric and magnetic radii are determined.

Strange magnetic moment is quantified.

Errors are an order of magnitude smaller than experimental uncertainties.

Abstract

We present the strange electromagnetic form factors of the nucleon using lattice QCD simulations with degenerate light, a strange, and a charm quark in the sea with masses tuned to their physical values. For the first time, the strange electromagnetic form factors are computed at the continuum limit using only ensembles simulated with physical quark masses, eliminating the need for chiral extrapolations and their associated systematic uncertainty. We obtain the momentum transfer dependence of the form factors using the $z$-expansion and provide the strange electric and magnetic radii, as well as the strange magnetic moment. When combining our statistical errors and systematic uncertainties stemming from the momentum transfer dependence fit, our errors are an order of magnitude smaller than those associated with experimental determinations of the strange electromagnetic form factor.