Search for narrow resonances inπpelastic scattering from the EPECUR experiment

Abstract

The analysis of high-precision π ± p → π ± 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 KΣ channel. However, a complete description of the data is improved with the addition of two narrow resonant structures at W ∼ 1.686 and W ∼ 1.720 GeV. These structures are interpreted as manifestations of S11 and P11 resonances. The underlying nature of the observed phenomena is discussed.

Towards Precision Spectroscopy of Baryonic Resonances

“…The analysis of photoproduction data could also benefit from improved data on pion-induced reactions, as recently achieved for elastic pion-nucleon scattering [6]. In Ref.…”

Compton scattering off proton in the third resonance region

“…energy range of around 1.6 -1.8 GeV [15,16]. The observed sharp structures seen in the beam asymmetry data with widths of around 25 MeV is thought to correlate with the narrow enhancement in the data of η photoproduction off the nucleon [17,18] and high-precision measurements of πp elastic differential cross sections [19,20]. So, Compton scattering off the nucleon in the resonance region is not only a suitable process to study helicity couplings of known resonances, but also an ideal tool to search for possible exotic states that might be weakly coupled to the πN state.…”

New narrow N(1685) and N(1726)? Remarks on the interpretation of the neutron anomaly as an interference phenomenon

“…, the precise data for the [18] and [19] reactions revealed two narrow structures at and 1.72 GeV (Figs. 3-5, respectively).…”

“…This work was supported by the High Energy Department, Petersburg Nuclear Physics Institute; by the INFN Section of Catania; and by the Ruhr Uni- cross section (figure from [19]). Red solid lines correspond to the calculations based on the Kmatrix approach with two narrow resonances.…”

“…Red solid lines correspond to the calculations based on the Kmatrix approach with two narrow resonances. See [19] for details.…”