The polarization observables T, P, and H and their impact on $\gamma p \to p\pi^0$ multipoles

TL;DR

This paper presents new, more precise polarization data for the reaction gamma p to p pi0, extending energy and angular coverage, which significantly refines the multipole analysis in neutral-pion photoproduction.

Contribution

It provides the first high-precision measurements of polarization observables T, P, and H for gamma p to p pi0, improving the multipole extraction in photoproduction analysis.

Findings

More precise polarization data than previous experiments.

Extended energy and angular coverage.

Significant narrowing of multipole error bands.

Abstract

Data on the polarization observables T, P, and H for the reaction $\gamma p\to p\pi^0$ are reported. Compared to earlier data from other experiments, our data are more precise and extend the covered range in energy and angle substantially. The results were extracted from azimuthal asymmetries measured using a transversely polarized target and linearly polarized photons. The data were taken at the Bonn electron stretcher accelerator ELSA with the CBELSA/TAPS detector. Within the Bonn-Gatchina partial wave analysis, the new polarization data lead to a significant narrowing of the error band for the multipoles for neutral-pion photoproduction.