Strangeness in the Nucleon

TL;DR

This paper investigates the hidden strangeness in the nucleon using an extended chiral constituent quark model, providing theoretical calculations that align well with various experimental indications of strangeness content.

Contribution

The work extends the chiral constituent quark model to include detailed calculations of strange quark parameters in the nucleon, offering a comprehensive theoretical analysis.

Findings

Consistent results with experimental data on strange quark contributions.

Calculated values for strange spin polarization and magnetic moments.

Enhanced understanding of nucleon structure regarding strangeness.

Abstract

There are several different experimental indications, such as the strangeness contribution to the magnetic moment of the proton, sigma_{\pi N} term, strange spin polarization, ratio of strange and non strange quark flavor distributions which suggest that the nucleon contains a hidden strangeness component which is contradictory to the naive constituent quark model. Chiral constituent quark model with configuration mixing (\chiCQM_{{\rm config}}) is known to provide a satisfactory explanation of the ``proton spin problem'' and related issues. In the present work, we have extended the model to carry out the calculations for the parameters pertaining to the strange quark content of the nucleon, for example, the strange spin polarization \Delta s, strange components of the weak axial vector form factors \Delta \Sigma and \Delta_8 as well as F and D, strangeness magnetic moment of the proton \mu_p^s, the strange quark content in the nucleon f_s coming from the \sigma_{\pi N} term, the ratios between strange and non-strange quarks \frac{2 s}{u+d} and \frac{2 s}{\bar u+ \bar d}, contribution of strangeness to angular momentum sum rule etc.. Our result demonstrates the broad consistency with the experimental observations as well as other theoretical considerations.