Transverse momentum spectra of hadrons in high energy pp and heavy ion collisions

Abstract

We present a study of transverse momentum (p T ) spectra of unidentified charged particles in pp collisions at RHIC and LHC energies from s 62.4 GeV = to 13 TeV using Tsallis/Hagedorn function. The power law of Tsallis/Hagedorn form gives very good description of the hadron spectra in p T range from 0.2 to 300 GeV/c. The power index n of the p T distributions is found to follow a function of the type a b s + with asymptotic value a=6.8. The parameter T governing the soft bulk contribution to the spectra remains almost same over wide range of collision energies. We also provide a Tsallis/Hagedorn fit to the p T spectra of hadrons in pPb and different centralities of PbPb collisions at s 5.02 TeV NN =. The data/fit shows deviations from the Tsallis distribution which become more pronounced as the system size increases. We suggest simple modifications in the Tsallis/Hagedorn power law function and show that the above deviations can be attributed to the transverse flow in low p T region and to the in-medium energy loss in high p T region.

A three component model for hadron $$p_\mathrm {T}$$-spectra in pp and Pb–Pb collisions at the LHC

“…The same is true also for the two component model based on the sum of Boltzmann-Gibbs distribution and a power-law term [15]. But for heavy-ion collisions and high multiplicity pp collisions these models fail to describe the measured spectra in the whole available p T range and more complex models were suggested [16][17][18][19][20][21][22][23][24], some of which include the hydrodynamical flow effects via the blast-wave model (BWM) [25,26]. The BWM alone is often used to fit the spectra in a limited p T range [13,14,[27][28][29][30] (e.g., p T ∼ 0.5-3 GeV/c [30]).…”

A three component model for hadron $p_{\rm T}$-spectra in pp and Pb-Pb collisions at the LHC

“…The same is true also for the two component model based on the sum of Boltzmann-Gibbs distribution and a power-law term [11]. But for heavyion collisions and high multiplicity pp collisions these models fail to describe the measured spectra in the whole available p T range and more complex models were suggested [12][13][14][15][16][17], some of which include the hydrodynamical flow effects via the blast-wave model (BWM) [18]. The BWM alone is often used to fit the spectra in a limited p T range [10,[19][20][21](e.g., p T ∼ 0.5-3 GeV/c [21]).…”

Centrality, transverse momentum and collision energy dependence of the Tsallis parameters in relativistic heavy-ion collisions

“…A non-extensive Tsallis statistics [1,2] has been shown to provide a better description of the nature of the non-exponential transverse momentum spectrum. The description of particle spectra using the Tsallis distribution has gained lots of interest recently because these could successfully explain the underlying physics in proton-proton (pp), proton-nucleus (p−A), and nucleus-nucleus (A−A) collision systems in dedicated facilities at the Relativistic Heavy-Ion collider (RHIC) and the Large Hadron Collider (LHC) [3][4][5][6][7][8][9][10][11][12]. Transverse momentum spectra of identified hadrons have significant importance to understand the collision dynamics, particle production mechanism, and thermodynamic behavior of the system.…”

“…The thermodynamical properties in pp collisions at the LHC energies using the different forms of the Tsallis distribution can be found in Ref. [6][7][8][9]. Dependence of Tsallis parameters on the particle multiplicity, p T ranges in pp system are reported in Ref.…”