EPECUR – Investigation of narrow baryon resonances Konovalova Elena St. Petersburg Nuclear Physics Institute (PNPI) with collaboration Institute of Theoretical and Experimental Physics (ITEP)

1.Introduction 2.Aim of our research 3.Description of the setup 4.Monte Carlo’ method 5.First results and summary Outline:

Introduction The problem of exotic resonances existance: Quantum chromodynamics doesn’t forbid such states but we haven’t experimental confirmation. Anti-Decuplet of Baryons (anti-decuplet in the chiral solution model by Diakonov, Petrov and Polyakov): horizontal lines - strangeness, sloping lines - charge. The problem of “missing” resonances: The Quark model of nucleons predicts existance of 434 baryons although the experiments are founded 135 (Rev.Part.Phys.)

Aim of Research Investigation of baryon resonance characteristics by precision measurement of the differential cross section of elastic pion- nucleon scattering (π - p→π - p) in the momentum range MeV/c. Energy resolution of the incident π-mesons achieved on the setup is approximately 0.1% and allows to investigate the fine structures (resonances) with small width.

Description of the Setup Structural elements of the setup: 1. Liquid hydrogen target (Φ=40 mm, L=256 mm) 2. Proportional chambers (step 1 mm) 3. Drift chambers (side of the cell hexagonal structure= 10 mm). Detection efficiency of tracks ~ 99% 4. Scintillation counters 5.Scintillation hodoscopes 6. Vacuum tube

Monte Carlo' Method 1) track of the particle and momentum (beam) are taken from real experimental data 2) the interaction points are distributed uniformly along the length of the target 3) to the point of interaction overlap all the geometric conditions that exist at the actual processing of the measurements 4) event is modeled uniformly over the phase space

Some Results 1. Sessions are performed at the accelerator ITEP (Moscow). As a result it was recorded ~ 2.95 billion of trigger events of which about 1.5% (~ 44 million) - the elastic events π-p — scattering. 2. It was created Monte Carlo model of the experimental setup which allows to: - simulate the events of the elastic π-p - scattering -obtain acceptance for the setup of this reaction. 3. Preliminary results are obtaned and we continues processing the experimental data.

Cross Section Dependence of the Scattering Angle Рlab = 1060 MeV/с Preliminary