3pi photo-production with CLAS

TL;DR

This paper analyzes the production of a three-pion system in photon-proton interactions at energies of 4.8-5.4 GeV using CLAS data, enabling study of excited mesons decaying into three pions.

Contribution

It presents a partial wave analysis of the 3π system, demonstrating suppression of baryon recoil events for clearer meson resonance investigation.

Findings

Successful partial wave analysis of 3π system.

Identification of meson decay channels in the 1-2 GeV range.

Reduction of baryon recoil event contamination.

Abstract

The $3\pi$ system produced in the reaction $\gamma p \to \pi^{+}\pi^{+}\pi^{-} n$ at $4.8-5.4$ GeV is investigated from the E01-017 (g6c) running of CLAS. This energy range allows for the study of excited mesons in the 1-2 GeV mass range, in their decay to $3\pi$, proceeding through $\rho \pi$ and $f_2 \pi$ emissions. At these energies, there is significant overlap in phase space for events with $\rho$ and $f_2$ production, recoiling off an excited baryon, such as the $\Delta(1232)$, $N^*(1520)$ and $N^*(1680)$. We show that after few kinematic selections, events of the latter type are suppressed in the final data set, allowing us to perform a PWA on the $3\pi$ system.