Study of pp Interactions at U-70

Abstract

Study of high multiplicity events is important for understanding of strong interaction nature, especially hadronization. The Thermalization project carried out on U-70 accelerator (IHEP, Protvino) is aimed at the search for collective phenomena both in quark-gluon plasma and secondary hadron system. On the level of 7 standard deviations the evidence of Bose–Einstein condensation of pions in the high multiplicity region has been confirmed at twofold increasing sampling. There are theoretical predictions that Bose-Einstein condensate is closely connected with excess of soft photon yield [S. Barshay, Phys.Lett. B227 (1989) 279]. To check up this assertion SVD Collaboration has manufactured a prototype of electromagnetic calorimeter with low energy threshold. The preliminary results are presented. Gluon dominance model (GDM) testifies this excess which can be stipulated by soft photon production. PACS numbers: 12.38.Mh, 12.40.Ee, 24.85.+p