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Radial flow and differential freeze-out in proton-proton collisions at \(\sqrt{s} = 7\) TeV at the LHC

  • Arvind Khuntia
  • Himanshu Sharma
  • Swatantra Kumar Tiwari
  • Raghunath SahooEmail author
  • Jean Cleymans
Regular Article - Theoretical Physics
  • 16 Downloads

Abstract.

We analyse the transverse momentum (\(p_{T}\))-spectra as a function of charged-particle multiplicity at midrapidity (\(\vert y\vert < 0.5\)) for various identified particles, such as \(\pi^{\pm}\), \(K^{\pm}\), \(K_{S}^{0}\), \(p+\overline{p}\), \(\phi\), \( K^{\ast 0} + \overline{K^{\ast 0}}\), and \(\Lambda + \bar{\Lambda}\) in proton-proton collisions at \( \sqrt{s} = 7\) TeV using Boltzmann-Gibbs Blast Wave (BGBW) model and thermodynamically consistent Tsallis distribution function. We obtain the multiplicity-dependent kinetic freeze-out temperature (\( T_{\rm kin}\)) and radial flow (\(\beta\)) of various particles after fitting the pT-distribution with BGBW model. Here, \( T_{\rm kin}\) exhibits mild dependence on multiplicity class while \( \beta\) shows almost independent behaviour. The information regarding Tsallis temperature and the non-extensivity parameter (q are drawn by fitting the \( p_{\rm T}\)-spectra with Tsallis distribution function. The extracted parameters of these particles are studied as a function of charged particle multiplicity density (\(\rm{d} N_{ch}/ \rm{d} \eta\)). In addition to this, we also study these parameters as a function of particle mass to observe any possible mass ordering. All the identified hadrons show a mass ordering in temperature, non-extensive parameter and also a strong dependence on multiplicity classes, except the lighter particles. It is observed that as the particle multiplicity increases, the q-parameter approaches to Boltzmann-Gibbs value, hence a conclusion can be drawn that system tends to thermal equilibrium. The observations are consistent with a differential freeze-out scenario of the produced particles.

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Copyright information

© SIF, Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • Arvind Khuntia
    • 1
  • Himanshu Sharma
    • 1
  • Swatantra Kumar Tiwari
    • 1
  • Raghunath Sahoo
    • 1
    Email author
  • Jean Cleymans
    • 2
  1. 1.Discipline of Physics, School of Basic SciencesIndian Institute of Technology IndoreIndoreIndia
  2. 2.UCT-CERN Research Centre and Department of PhysicsUniversity of Cape TownRondeboschSouth Africa

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