Abstract
The differential cross-section in squared momentum transfer of ρ , ρ 0 , ω , ϕ , f 0 980 , f 1 1285 , f 0 1370 , f 1 1420 , f 0 1500 , and J / ψ produced in high-energy virtual photon-proton ( γ ∗ p ), photon-proton ( γ p ), and proton-proton ( p p ) collisions measured by the H1, ZEUS, and WA102 Collaborations is analyzed by the Monte Carlo calculations. In the calculations, the Erlang distribution, Tsallis distribution, and Hagedorn function are separately used to describe the transverse momentum spectra of the emitted particles. Our results show that the initial- and final-state temperatures increase from lower squared photon virtuality to a higher one and decrease with the increase of center-of-mass energy.
Highlights
In high-energy collisions, it is interesting for us to describe the excitation and equilibrium degrees of an interacting system because of the two degrees related to the reaction mechanism and evolution process of the collision system [1,2,3,4,5,6,7,8,9,10]
The initial temperature Ti can be extracted by fitting the transverse momentum pT spectra of particles by using some distributions such as the Erlang distribution [19,20,21], Tsallis distribution [22, 23], Hagedorn function [24], and Lévy–Tsallis function [25]
Because the same experimental condition is used in statistics, lots of events are in equilibrium if they consist of a large statistical system which can be described by the grand canonical ensemble
Summary
In high-energy collisions, it is interesting for us to describe the excitation and equilibrium degrees of an interacting system because of the two degrees related to the reaction mechanism and evolution process of the collision system [1,2,3,4,5,6,7,8,9,10]. In high-energy collisions, different types of temperature are used [11,12,13,14,15,16,17,18], which usually refer to the initial temperature Ti, quark-hadron transition temperature Ttr, chemical freeze-out temperature Tch, kinetic freeze-out or final-state temperature (“confinement” temperature) Tkin or T0, and effective temperature Tef f or T, etc. The initial temperature Ti is the temperature of emission source or interacting system when a projectile particle or nucleus and a target particle or nucleus undergo the initial stage of a collision. It represents the excitation degree of the emission source or that of an interacting system in the initial state of collisions, and it is usually meant as describing the interacting system after thermalization. The initial temperature Ti can be extracted by fitting the transverse momentum pT spectra of particles by using some distributions such as the Erlang distribution [19,20,21], Tsallis distribution [22, 23], Hagedorn function [24], and Lévy–Tsallis function [25]
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