Experiment EPECUR for High Precision Measurements of the Pion Proton Cross Section in the Second Resonance Region

Abstract

In the search of light baryon resonances the main role is still held by partial wave analysis of the elastic pion-proton scattering. Yet most of the data available for PWA were obtained 20 years ago and earlier with an accuracy achievable at those times. One of the aims of EPECUR collaboration is to get qualitatively new experimental data in the pion-proton scattering. The experiment combines very high, better than 1 MeV, resolution in the invariant mass with high statistics. This makes it possible to look for narrow resonances with the coupling to the π p channel as low as 5%. One of such objects is 1-star N(1685) resonance. Over 3 billions triggers of both positive and negative pion beams in momentum range 820-1330 MeV/c were recorded since experiment start in 2009.