Calculation of nucleon strange quark content with dynamical overlap quarks

TL;DR

This paper directly computes the nucleon strange quark content using lattice QCD with overlap quarks, achieving precise results that agree with previous indirect methods.

Contribution

It presents a direct calculation of the nucleon strange quark content using dynamical overlap quarks and advanced statistical techniques, improving accuracy over prior indirect estimates.

Findings

The y parameter is 0.024(45) at the physical point.

Results agree with earlier spectrum-based calculations.

Uses low-mode averaging and all-to-all propagators for improved statistics.

Abstract

We calculate the nucleon strange quark content directly from disconnected three-point functions. Numerical simulations are carried out in two-flavor QCD using the overlap quark action with up and down quark masses down to a fifth of the physical strange quark mass. To improve the statistical accuracy, we calculate the nucleon two-point functions with the low-mode averaging technique, whereas the all-to-all quark propagator is used for the disconnected quark loop. We obtain the y parameter, which is the ratio of the strange and light quark contents, y = 0.024(45) at the physical point. This is in a good agreement with our earlier calculation from the nucleon spectrum through the Feynman-Hellmann theorem.