Partial-wave decomposition of the diffractively produced $\pi^-\pi^+\pi^-\eta$ final state at COMPASS

TL;DR

This paper presents the first high-statistics partial-wave analysis of the diffractive $ o ext{multi-meson}$ final state at COMPASS, aiming to explore the light meson spectrum and search for exotic hybrid states.

Contribution

It provides a comprehensive partial-wave decomposition of a complex diffractive reaction, including decay channels relevant for hybrid meson hypotheses, advancing the understanding of light meson spectroscopy.

Findings

First high-statistics partial-wave analysis of this reaction

Includes decay channels predicted for hybrid mesons

Provides data to test hybrid meson hypotheses

Abstract

One of the prime goals of the COMPASS experiment at CERN is the study of the light meson spectrum, with a particular emphasis on the search for exotic states. We present the first high-statistics partial-wave decomposition of the diffractive reaction $\pi^-+p\to \pi^-\pi^+\pi^-\eta+p$, which spans a wide range of decay channels, such as $f_1(1285)\pi^-$, $a_2^-(1320)\eta$, $\eta^\prime\pi^-$, and $\rho(770)a_0^-(980)$. This analysis also includes decay channels, i.e. $f_1(1285)\pi^-$ and $\eta^\prime\pi^-$, predicted by theoretical models for the lightest hybrid meson and providing the opportunity to verify the hybrid meson hypothesis of the $\pi_1(1600)$.