Introduction, news

• Евгений Солдатов

Quark counting rules for the inclusive cross-section for the production of particles with large transverse momenta at midrapidities

• Vladimir Vechernin (St. Petersburg State University)

The theoretical approach developed earlier for the microscopic description of cumulative phenomena in proton-nucleus interactions and taking into account only the interaction of a nucleon with a flucton is generalized to the case of interaction of two fluctons in a collision of nuclei. On this basis, an analysis of the pion production process in AA collisions in a new cumulative region of central rapidities and large transverse momenta, accessible for experimental study at the SPD and MPD facilities of the NICA collider, is carried out. It is shown that the contribution of the flucton-flucton interaction with the emission of a quark fragmentation into a pion dominates in this region. The asymptotic behavior of the cross section of this process is calculated at high initial energies near the kinematic boundary of the process and the quark counting rules for the inclusive cross section in the region of central rapidities and high transverse momenta are formulated. The obtained expressions give an explicit form of the dependence of the inclusive cross section of cumulative pion production on the initial energy and the so-called cumulative number near the kinematic boundary of the AA collision. It is verified that the new microscopic approach, developed to describe the inclusive production of particles in the new cumulative region, when applied to describe elastic and quasi-elastic processes with large momentum transfer, correctly reproduces the previously obtained quark counting rules for these processes. It is shown that according to the obtained new quark counting rules, the decrease of the inclusive cross section with increasing initial energy turns out to be significantly slower than for elastic and quasi-elastic processes. At the same time, it contains an additional small factor depending on the deviation of the cumulative number x from its maximum possible value A.