Normalization discrepancies in photoproduction reactions

TL;DR

This paper investigates normalization discrepancies in photoproduction reaction data from different experiments, highlighting their impact on coupling constant determinations and emphasizing the importance of consistent normalization methods.

Contribution

It provides a comprehensive survey of normalization issues in photoproduction data, comparing results from tagged and untagged photon beams and analyzing their effects on partial wave analyses.

Findings

CLAS results are about half of older untagged beam data.

CLAS results agree with recent tagged beam experiments like LEPS.

Normalization discrepancies significantly affect coupling constant extractions.

Abstract

Recent CLAS photoproduction results using a tagged bremsstrahlung photon beam for the ground-state pseudoscalar meson photoproduction channels ($K^+ \Lambda$, $K^+ \Sigma^0$, $\eta p$, $\pi^+ n$ and $\pi^0 p$) show a normalization discrepancy with older results from SLAC, DESY and CEA that used an untagged bremsstrahlung beam. The CLAS results are roughly a factor of two smaller than the older data. The CLAS $K^+\Lambda$ and $K^+\Sigma^0$ results are in excellent agreement with the latest LEPS results that also employed a tagged beam. For the vector meson ($\omega p$ and $\phi p$) channels, CLAS agrees with SLAC results that employed a linearly polarized beam using laser back-scattering, as well as Daresbury data that also came from tagged photon experiment. We perform a global survey of these normalization issues and stress on their significant effect on the coupling constants used in various partial wave analyses.