Eta Photoproduction as a Test of the Extended Chiral Symmetry

TL;DR

This paper investigates eta photoproduction off protons to test extended chiral symmetry, finding a preference for pseudoscalar coupling and highlighting the need for more comprehensive electromagnetic data.

Contribution

It introduces an effective Lagrangian approach that mixes pseudoscalar and pseudovector eta couplings to estimate chiral symmetry violation.

Findings

Data favors pseudoscalar coupling at 91%

Current electromagnetic data is insufficient for conclusive results

The mixing ratio estimates symmetry breaking

Abstract

We analyze the $\gamma p \to \eta p$ process from threshold up to 1.2 GeV, employing an effective Lagrangian approach that allows for a mixing of eta couplings of pseudoscalar and pseudovector nature. The mixing ratio of the couplings may serve as a quantitative estimation of the $SU_L(3)\times SU_R(3)$ extended chiral symmetry violation in this energy regime. The data analyzed (differential cross sections and asymmetries) show a preference for the pseudoscalar coupling -- 91% of pseudoscalar coupling component for the best fit. We stress that a more conclusive answer to this question requires a more complete electromagnetic multipole database than the presently available one.