Search for narrow resonances in $\pi p$ elastic scattering from the EPECUR experiment

TL;DR

This paper analyzes high-precision pion-proton scattering data to identify narrow resonances, revealing two new structures at specific energies that suggest potential new baryonic states.

Contribution

The study introduces a multichannel $K$-matrix approach to better describe scattering data and identifies two narrow resonances not previously confirmed.

Findings

Identification of two narrow resonant structures at 1.686 and 1.720 GeV.

Some features are due to the opening of the $K ext{Sigma}$ channel.

Enhanced data description with the addition of new resonances.

Abstract

The analysis of high-precision $\pi^{\pm}p \to \pi^{\pm}p$ cross section data from the EPECUR Collaboration based on the multichannel $K$-matrix approach is presented.The sharp structures seen in these data are studied in terms of both opening thresholds and new resonance contributions. Some prominent features are found to be due to the opening $K\Sigma$ channel. However, a complete description of the data is improved with the addition of two narrow resonant structures at $W\sim 1.686$ and $W\sim 1.720$ GeV. These structures are interpreted as manifestations of $S_{11}$ and $P_{11}$ resonances. The underlying nature of the observed phenomena is discussed.