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

摘要

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