HADRON SPECTRA IN p plus p COLLISIONS AT RHIC AND LHC ENERGIES

We present the systematic analysis of transverse momentum (p(T)) spectra of identified hadrons in p + p collisions at Relativistic Heavy Ion Collider (root s = 62.4 and 200 GeV) and at Large Hadron Collider (LHC) energies (root s = 0.9, 2.76 and 7.0 TeV) using phenomenological fit functions. We review various forms of Hagedorn and Tsallis distributions and show their equivalence. We use Tsallis distribution which successfully describes the spectra in p + p collisions using two parameters, Tsallis temperature T which governs the soft bulk spectra and power n which determines the initial production in partonic collisions. We obtain these parameters for pions, kaons and protons as a function of center-of-mass energy (root s). It is found that the parameter T has a weak but decreasing trend with increasing root s. The parameter n decreases with increasing root s which shows that production of hadrons at higher energies are increasingly dominated by point like qq scatterings. Another important observation is with increasing root s, the separation between the powers for protons and pions narrows down hinting that the baryons and mesons are governed by same production process as one moves to the highest LHC energy.