# Nucleon resonances in $\gamma p \to \omega p$ reaction

## TL;DR

This study analyzes high-precision experimental data on $oldsymbol{ ext{γ} p o ext{ω} p}$ reactions using an effective Lagrangian approach, identifying key nucleon resonances and extracting their parameters.

## Contribution

It introduces a comprehensive analysis of spin observables and cross sections within an effective Lagrangian framework, identifying specific nucleon resonances involved in the reaction.

## Key findings

- All CLAS data are well described by the model.
- Identified key nucleon resonances contributing to the reaction.
- Extracted resonance parameters align with PDG values.

## Abstract

The most recent high-precision data on spin observables $\Sigma$, $T$, $P'$, $E$, $F$ and $H$ reported by the CLAS Collaboration together with the previous data on differential cross sections and spin-density-matrix elements reported by the CLAS, A2, GRAAL, SAPHIR and CBELSA/TAPS Collaborations for the reaction $\gamma p \to \omega p$ are analyzed within an effective Lagrangian approach. The reaction amplitude is constructed by considering the $t$-channel $\pi$ and $\eta$ exchanges, the $s$-channel nucleon and nucleon resonances exchanges, the $u$-channel nucleon exchange and the generalized contact current. The latter accounts effectively for the interaction current and ensures that the full photoproduction amplitude is gauge invariant. It is shown that all the available CLAS data can be satisfactorily described by considering the $N(1520)3/2^-$, $N(1700)3/2^-$, $N(1720)3/2^+$, $N(1860)5/2^+$, $N(1875)3/2^-$, $N(1895)1/2^-$ and $N(2060)5/2^-$ resonances in the $s$-channel. The parameters of these resonances are extracted and compared with those quoted by PDG.