Amplitude analysis of resonant production in three pions

TL;DR

This paper analyzes three-pion resonances using reaction amplitudes that respect fundamental principles, leveraging recent large data sets to study specific resonances in high-energy diffractive processes.

Contribution

It introduces a unitarity-constrained isobar model for analyzing three-pion resonances in high-energy diffractive scattering, based on recent large data sets.

Findings

Identification of the $J^{PC}=2^{-+}$ resonance in $ ho o ext{pi}$ and $f_2 o ext{pi}$ channels

Development of reaction amplitudes satisfying $S$-matrix principles

Application of the model to COMPASS data

Abstract

We present some results on the analysis of three pion resonances. The analyses are motivated by the recent release of the largest data set on diffractively produced three pions by the COMPASS collaboration. We construct reaction amplitudes that satisfy fundamental $S$-matrix principles, which allows the use of models that have physical constraints to be used in fitting data. The models are motivated by the isobar model that satisfy unitarity constraints. The model consist of a Deck production amplitude with which final state interactions are constrained by unitarity. We employ the isobar model where two of the pions form a quasi-stable particle. The analysis is performed in the high-energy, single Regge limit. We specifically discuss the examples of the three pion $J^{PC}=2^{-+}$ resonance in the $\rho\pi$ and $f_2\pi$ channels.