New results on narrow structure in the pion nucleon elastic scattering from the EPECUR experiment.

Abstract

The new block of high precision data from EPECUR Collaboration is presented. The data has better than 1 MeV resolution in the invariant mass and show some interesting structure for negative pions. The multichannel K-matrix analysis allows explain this structure by two narrow (~20 MeV) resonances with masses 1686 and 1710 MeV. The influence of these resonances on the other channels is discussed also.

Search for narrow resonances inπpelastic scattering from the EPECUR experiment

“…The π − p → π − p data revealed two narrow structures, at W ∼ 1.686 and at W ∼ 1.720 GeV, which were not seen in π + p scattering [30]. This clearly shows that the observed structures appear in the isospin I=1/2 sector only.…”

“…In Ref. [30], a preliminary analysis of the data from Ref. [33] was presented, with the finding that these structures could be described by two narrow (width ∼ 25 MeV) S 11 and P 11 resonances.…”