The analysis of reactions $\pi N\to two mesons + N$ within reggeon exchanges. 1. Fit and results

TL;DR

This paper employs reggeon exchange techniques to analyze reactions producing two mesons and a nucleon at high energies, fitting data from multiple reactions to study various meson resonances and their properties.

Contribution

It introduces a direct reggeon exchange approach for simultaneous description of mass and momentum transfer distributions in meson production reactions, expanding analysis to multiple related processes.

Findings

Successful simultaneous fits to multiple meson spectra

Identification of resonance parameters for various mesons

Enhanced understanding of meson production mechanisms

Abstract

The novel point of this analysis is a direct use of reggeon exchange technique for the description of the reactions $\pi N\to two mesons + N$ at large energies of the initial pion. This approach allows us to describe simultaneously distributions over $M$ (invariant mass of two mesons) and $t$ (momentum transfer squared to nucleons). Making use of this technique, the following resonances (as well as corresponding bare states), produced in the $\pi N\to \pi^0\pi^0 N$ reaction are studied: $f_0(980)$, $f_0(1300)$, $f_0(1200-1600)$, $f_0(1500)$, $f_0(1750)$, $f_2(1270)$, $f_2(1525)$, $f_2(1565)$, $f_2(2020)$, $f_4(2025)$. Adding data for the reactions $p\bar p({\rm at rest, from liquid H_2})\to \pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta$, $\pi^0\eta\eta$ and $p\bar p({\rm at rest, from gaseous H_2})\to \pi^0\pi^0\pi^0$, $\pi^0\pi^0\eta$, $\pi^0\eta\eta$, we have performed simultaneous $K$-matrix fits of two-meson spectra in all these reactions. The results of combined fits to the above-listed isoscalar $f_J$-states and to isovector ones, $a_0(980)$, $a_0(1475)$, $a_2(1320)$, are presented.