Universality of particle production and energy balance in hadronic and nuclear collisions

Aditya Nath Mishra,Edward K G Sarkisyan,Alexander S Sakharov,Raghunath Sahoo

doi:10.1051/epjconf/201612001007

Abstract

The multihadron production in nucleus-nucleus and (anti)proton-proton col- lisions is studied by exploring the collision-energy and centrality dependencies of the mean multiplicity in the existing data. The study is performed in the framework of the re- cently proposed effective-energy approach which combines the constituent quark picture and Landau hydrodynamics counting for the centrality-defined effective energy of partic- ipants. Within this approach, the multiplicity energy dependence and the pseudorapidity spectra from the most central nuclear collisions are well reproduced. The study of the multiplicity centrality dependence reveals a new scaling between the measured pseudora- pidity spectra and the calculations. Using this scaling, called the energy balanced limiting fragmentation scaling, the pseudorapidity spectra are well reproduced for all centralities. The scaling clarifies some differences in the multiplicity and midrapidity density central- ity dependence from RHIC and LHC. A similarity in the multiplicity energy dependence in the most central collisions and centrality data is shown. Predictions are drawn for the mean multiplicities to be measured in hadronic and heavy-ion collisions at the LHC. 1. In this report, we discuss our recent results on the universality of multiparticle production in nucleus-nucleus (AA) and hadronic interactions in view of a new scaling obtained (1). The study ex- ploites concept of effective energy (2) employed for the data interpreted in terms of the approach of the dissipating energy of quark participants (3, 4), or, for brevity, the participant dissipating energy (PDE) approach. This approach combines the constituent quark picture together with Landau relativistic hy- drodynamics and interrelates different types of collisions. The earlier observations (2) are made by studying the dependencies of the pseudorapidity density and transverse energy pseudorapidity den- sity at midrapidity on the collision center-of-mass (c.m.) energy in hadronic and the most central (head-on) AA collisions and on the number of nucleon participants, or centrality, in AA collisions in the entire available energy range of the existing data. The complementarity of the measurements in

Highlights

Non-central and head-on AA collisions is shown
In the framework of the participant dissipating energy (PDE) approach, we extend the previous studies of the charged particle mean multiplicity [3, 4] to LHC energies
This makes the secondary particle production to be basically driven by the amount of the initial effective energy deposited by constituent quarks

Summary

Nch and

Ncphp are the mean multiplicities in AA and nucleon-nucleon collisions, respectively, and Npart is the number of participants. √OsnNNe can see that the calculated Nch/(0.5Npart) values follow the measurements from AA collisions from a few GeV up to the TeV LHC energy. This points to the universality of the multiparticle production in the different types of collisions. This becomes even clearer when the 200 GeV PHOBOS data are multiplied by a factor of 2.87 which allows matching the ALICE data from the highly central collisions. ) and, as expected, due to a slight non-centrality It is noticeable how well the PDE picture allows one to reproduce the pseudorapidity density distributions in AA interactions in the full-η range, from central-η to forward-η.

Predictions for LHC

ISR bubble chamber