Evidence for Narrow N*(1685) Resonance in Quasifree Compton Scattering on the Neutron

TL;DR

This study provides evidence for a narrow nucleon resonance at 1.685 GeV in quasifree Compton scattering on the neutron, indicating a potentially new resonance with unique properties and stronger neutron excitation.

Contribution

First measurement of quasi-free Compton scattering on the neutron revealing a narrow resonance at 1.685 GeV, supporting the existence of a new nucleon state.

Findings

Identification of a narrow peak at W~1.685 GeV in neutron Compton scattering

Evidence of a resonance with width ≤ 30 MeV

Stronger photoexcitation on the neutron compared to the proton

Abstract

The first study of quasi-free Compton scattering on the neutron in the energy range of $E_{\gamma}=0.75 - 1.5$ GeV is presented. The data reveals a narrow peak at $W\sim 1.685$ GeV. This result, being considered in conjunction with the recent evidence for a narrow structure at $W\sim 1.68$GeV in the $\eta$ photoproduction on the neutron, suggests the existence of a new nucleon resonance with unusual properties: the mass $M\sim 1.685$GeV, the narrow width $\Gamma \leq 30$MeV, and the much stronger photoexcitation on the neutron than on the proton.