Partial wave analysis of the reaction gamma p -> p omega$ and the search for nucleon resonances

TL;DR

This study performs a detailed partial wave analysis of gamma p -> p omega reactions using high-precision data, confirming known resonances and suggesting a potential new nucleon resonance around 2 GeV.

Contribution

It introduces an event-based partial wave analysis incorporating the first high-precision spin density matrix measurements for this reaction.

Findings

Confirmed dominance of t-channel pi0 exchange at forward angles.

Identified known resonances F15(1680), D13(1700), G17(2190).

Provided suggestive evidence for a new J(P)=5/2(+) state near 2 GeV.

Abstract

An event-based partial wave analysis (PWA) of the reaction gamma p -> p omega has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world's first high precision spin density matrix element measurements, available to the event-based PWA through the decay distribution of omega-> pi+ pi - pi0. The data confirm the dominance of the t-channel pi0 exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F[15](1680) and D[13](1700) near threshold, as well as the G[17](2190) at higher energies. Suggestive evidence for the presence of a J(P)=5/2(+) state around 2 GeV, a "missing" state, has also been found. Evidence for other states is inconclusive.