Pseudoscalar and Scalar Meson Photoproduction Interpreted by Regge Phenomenology

TL;DR

This paper uses Regge phenomenology to analyze pseudoscalar and scalar meson photoproduction, comparing data sets and predicting high-energy polarization observables, revealing differences in experimental results and meson exchange contributions.

Contribution

It provides a Regge-based model for meson photoproduction that clarifies discrepancies in experimental data and predicts polarization observables at high energies.

Findings

SLAC and Gluex data show discrepancies in $ heta$-independent measurements.

Regge model predicts opposite beam polarization asymmetries for scalar and pseudoscalar mesons.

Vector meson exchange dominates, with minimal pseudovector contribution.

Abstract

We have evaluated pseudoscalar and scalar neutral pion photoproduction in $\vec{\gamma}p\to\pi^0p$ and $\vec{\gamma}p\to a_0^0p$ above the resonance region and within Regge phenomenology. Our fit, including GlueX $\Sigma$ pseudoscalar photoproduction data, shows that previous SLAC $\Sigma$ measurements for $\vec{\gamma}p \to \pi^0p$ above $E_\gamma = 4~\mathrm{GeV}$ are at variance with SLAC data with more recent measurements made by GlueX in vicinity of $E_\gamma = 9~\mathrm{GeV}$. The Regge model predicts that the beam polarization asymmetry $\Sigma$ of the scalar meson is opposite to that of pseudoscalar meson photoproduction, however, the cross sections are similar. While the vector natural parity meson exchange is dominant in both cases, the contribution of the pseudovector unnatural parity meson exchange is very small. Using Regge phenomenology, we predicted high energy behavior for double polarized observables $\mathbb{E}$, $\mathbb{F}$, $\mathbb{G}$, and $\mathbb{H}$ for the reactions $\gamma p\to \pi^0p$ and $\gamma p\to a_0^0p$.