Confirmation of the X(1835) and observation of the resonances X(2120) and X(2370) in J/psi->gamma pi^+pi^-eta'

TL;DR

This study confirms the X(1835) resonance and reports the observation of two new resonances, X(2120) and X(2370), in J/psi decays, using a large data sample from the BESIII detector, with high statistical significance.

Contribution

The paper provides the first confirmation of X(1835) with higher significance and reports the discovery of two new resonances in J/psi decay channels, expanding understanding of these states.

Findings

X(1835) confirmed with >20σ significance

X(2120) observed with >7.2σ significance

X(2370) observed with >6.4σ significance

Abstract

With a sample of (225.2\pm2.8)*10^{6} J/psi events registered in the BESIII detector, J/psi->gamma pi^+ pi^- eta' is studied using two eta' decay modes: eta'->pi^+ pi^- eta and eta' -> gamma rho^0. The X(1835), which was previously observed by BESII, is confirmed with a statistical significance that is larger than 20\sigma. In addition, in the pi^+pi^-eta' invariant mass spectrum, the X(2120) and the X(2370), are observed with statistical significances larger than 7.2\sigma and 6.4\sigma, respectively. For the X(1835), the angular distribution of the radiative photon is consistent with expectations for a pseudoscalar.