On statistical mechanics developments of clan concept in multiparticle production

Abstract

Clan concept has been introduced in multiparticle dynamics in order to interpret the wide occurrence of negative binomial (NB) regularity in n-charged particle multiplicity distributions (MDs) in various high energy collisions. The centrality of clan concept led to the attempt to justify its occurrence within a statistical model of clan formation and evolution. In this framework all thermodynamical potentials have been explicitely calculated in terms of NB parameters. Interestingly it was found that NB parameter k corresponds to the one particle canonical partition function. The goal of this paper is to explore a possible temperature T and volume V dependence of parameter k in various classes of events in high energy hadron-hadron collisions. It is shown that the existence of a phase transition at parton level from the ideal clan gas associated to the semihard component with k > 1 to the ideal clan gas of the hard component with k < 1 implies a discontinuity in the average number of particles at hadron level.

Prospects of Searching for (Un)particles From Hidden Sectors Using Rapidity Correlations in Multiparticle Production at the LHC

“…Finally, it is particularly interesting for us to note that the average number of clans has been found to be decreasing with √ s in semihard and hard processes (even approaching one in a certain class of events [3]) while the mean number of particles per clan should increase accordingly [45,46].…”

“…These parameters are related to the standard ones by: N c = k ln (1 + n /k) and n c = n / N c , where 1/k can be interpreted as a determination of the aggregation of partons into clusters/clans. Recently [45], the parameter k has been related to a phase transition at parton level implying a discontinuity in the average number of hadrons in high-energy hadronic collisions.…”

A look at multiparticle production via modified combinants

“…Due to the inability of perturbative Quantum Chromodynamics (pQCD) to provide a complete theoretical account for the observed MDs incorporating both the hard and soft processes, various phenomenological approaches had to be adopted. These can range from dynamical approaches in the form of coloured string interactions [1] and dual-parton model [2], to geometrical approaches [3,4] resulting in the fireball model [5], stochastic approaches [6,7,8] modelling high energy collision as branching [6,7,8] or clans [9].…”

How to retrieve additional information from the multiplicity distributions

“…In multiparticle production phenomenology the NBD has been obtained in the bag model [13], in the stochastic bootstrap model [14,15], in numerous descriptions using branching and stochastic processes [16,17,18], in popular and frequently used clan model [5,19,20] (for its more theoretical justification see [21,22]), or using a general form of the grand canonical partition function [23,24,25]. It also describes in a natural way different kinds of multiparton interactions [26,27,28] and the production of some specific initial gluonic states in the first phase of the interaction process, the so called "glittering glasmas" [29].…”