# Constructing new pseudoscalar meson nonets with the observed $X(2100)$, $X(2500)$, and $\eta(2225)$

## TL;DR

This paper proposes new classifications for recently observed pseudoscalar mesons, suggesting they form two new nonets based on mass spectra and decay analysis, with further experimental verification needed.

## Contribution

It introduces a novel assignment of observed mesons into two new pseudoscalar nonets based on spectral and decay analysis, expanding the understanding of meson classification.

## Key findings

- X(2120) and η(2225) may form a nonet with π(2070) and K(2150)
- X(2500), X(2370), π(2360), and K(2414) form another nonet
- Further experimental data are necessary to confirm these nonet assignments

## Abstract

Stimulated by the BESIII observation of $X(2100)$, $X(2500)$, and $\eta(2225)$, we try to pin down new pseudoscalar meson nonets including these states. The analysis of mass spectra and the study of strong decays indicate that $X(2120)$ and $\eta(2225)$ associated with $\pi(2070)$ and the predicted kaon $K(2150)$ may form a new pseudoscalar meson nonet. In addition, more experimental data for $X(2100)$ are necessary to determine its structure of nonets. Then, $X(2500)$, $X(2370)$, $\pi(2360)$, and the predicted kaon $K(2414)$ can be grouped into another new nonet. These assignments to the discussed pseudoscalar states can be further tested in experiment.