Multiplicity Studies and Effective Energy in ALICE at the LHC

Abstract

In this work we explore the possibility to perform ``effective energy'' studies in very high energy collisions at the CERN Large Hadron Collider (LHC). In particular, we focus on the possibility to measure in $pp$ collisions the average charged multiplicity as a function of the effective energy with the ALICE experiment, using its capability to measure the energy of the leading baryons with the Zero Degree Calorimeters. Analyses of this kind have been done at lower centre--of--mass energies and have shown that, once the appropriate kinematic variables are chosen, particle production is characterized by universal properties: no matter the nature of the interacting particles, the final states have identical features. Assuming that this universality picture can be extended to {\it ion--ion} collisions, as suggested by recent results from RHIC experiments, a novel approach based on the scaling hypothesis for limiting fragmentation has been used to derive the expected charged event multiplicity in $AA$ interactions at LHC. This leads to scenarios where the multiplicity is significantly lower compared to most of the predictions from the models currently used to describe high energy $AA$ collisions. A mean charged multiplicity of about 1000-2000 per rapidity unit (at $\eta \sim 0$) is expected for the most central $Pb-Pb$ collisions at $\sqrt{s_{NN}}=5.5TeV$.

arXiv comment12 pages, 19 figures. In memory of A. Smirnitskiy

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Cited by in corpus (5)

• Charged-Particle Multiplicity in Proton-Proton Collisions
• Prospects of searching for (un)particles from Hidden Sectors using rapidity correlations in multiparticle production at the LHC
• Universality of multiplicity distribution in proton-proton and electron-positron collisions
• A multi-differential investigation of strangeness production in pp collisions with ALICE
• First observation of strange baryon enhancement with effective energy in pp collisions at the LHC