Possible observation of phase transitions in nucleon-nucleon systems

Abstract

A simple condition of deep cooling for observation of phase transitions in compressed fewnucleon systems was recently proposed. Here we have checked it using data obtained in the first physical experiment with accelerated nuclei at JINR synchrophasotron. Our study was inspired by a remark made by A.M. Baldin et al that one of peaks in observed double differential crosssection may arise due to an "excited state of deuterium nucleus". We have established that one of the peaks in the cross-section corresponds indeed to the dibaryon reported by WASA-at-COSY Collaboration. Another peak in the same region may be explained by interference of several usual baryon resonances. Even a more amazing fact has been established in a kinematical regions which were considered till now as a contribution of elastic deuteron-deuteron and nucleon(inside deuteron)-deuteron scattering. More careful calculations have shown that it is not the case. Trying to understand the nature of these peaks we looked over many dibaryons reported by different experimental groups and found that they may be excellently explained in terms of light dibaryons with equidistant mass spectrum observed by Yu.A. Troyan in a very different experiment. A natural explanation of these dibaryons may be given on basis of generalized coherent states discovered by A. Perelomov. These light dibaryons can be an experimental evidence for the pion Bose-Einstein condensate appearance in compressed and cooled nucleon systems. The condensate emerges due to a nonperturbative effect described by Bogoliubov's transformation which produces a pion state beyond the range of the Fock space. It should be also noted that this state of pion field has a mathematical and physical prototype in quantum optics, known there as the squeezed vacuum. Further experimental studies based on modern experimental facilities and more abundant statistics are necessary to verify our conclusions. September 15-20, 2014 JINR, Dubna, Russia * Speaker. . The dashed and dotted curves correspond to approximations of the first two peaks by the Gaussian functions which maxima positions are given in the insertion. XXII International Baldin Seminar on High Energy Physics Problems

Coherent dibaryons

“…The possibility of deep cooling by CP was checked using data of paper [4] in which a hint on existence of an "excited state of deutron" was noticed already in 1979. Our analysis showed [5,6] that subtle contours of the dibaryon which was observed by WASA-at-COSY Collaboration [7] are seen indeed in a right place suggested in [4]. Hereafter these data are referred to as the Stavinskii group experiment (SGE) and data from [3] as the Troyan experiment (TE) data.…”

“…The main surprise waited for us in the range of two other peaks observed in SGE, which were never analyzed before but identified a priori with elastic d-d and d-N scattering. Calculations revealed this is definitely not so, and the peaks correspond very surprisingly to transitions between different dibaryons from TE [5,6]. It will be shown below that an explanation of this unexpected result is connected with elucidation of a transverse momentum anomaly found out in data of EVA group [8] in paper [2].…”

“…Indeed, due to Landau-Peierls uncertainty relation, masses of target and incident deuterons in the initial state were not fixed exactly and some of the excited dibaryon levels might show themselves in the peaks observed. Overwhelming contribution of projectile's excited states as compared with target's ones, which was established in [5,6], may be a manifestation of the relativistic effect of time dilation that allows highly excited states to exist much longer in the incident deuteron (see section 5).…”

“…Transformation of creation and annihilation operators corresponding to (5) is the following (in vector notations):…”

On possible contribution of partons’ orbital momentum to the proton spin

“…Results of experiment [12,13] fulfilled already in 1993 give a possible candidate for the phenomenon. A detailed analysis of the papers [12,13] may be found in [14]. Below we sketch a probable theoretical approach to description of these data.…”