Fixed-t analyticity as a constraint in single energy partial wave analyses of meson photoproduction reactions

TL;DR

This paper introduces a novel fixed-t analyticity constraint method for single-energy partial wave analyses of meson photoproduction, improving the extraction of baryon resonance information from experimental data.

Contribution

It develops an iterative fixed-t analyticity approach that constrains partial wave solutions, tested with pseudo and real data, enhancing analysis accuracy in meson photoproduction.

Findings

Successful application to pseudo data demonstrating ambiguity reduction.

Analysis of experimental data from MAMI and GRAAL shows improved partial wave solutions.

Method provides a new constraint technique for baryon spectroscopy studies.

Abstract

Partial wave amplitudes of meson photoproduction reactions are an important source of information in baryon spectroscopy. We investigate a new approach in single-energy partial wave analyses of these reactions. Instead of using a constraint to theoretical models in order to achieve solutions which are continuous in energy, we enforce the analyticity of the amplitudes at fixed values of the Mandelstam variable $t$. We present an iterative procedure with successive fixed-$t$ amplitude analyses which constrain the single-energy partial wave analyses and apply this method to the $\gamma p \to \eta p$ reaction. We use pseudo data, generated by the EtaMAID model, to test the method and to analyze ambiguities. Finally, we present an analytically constrained partial wave analysis using experimental data for four polarization observables recently measured at MAMI and GRAAL in the energy range from threshold to $\sqrt{s}=1.85$ GeV.