Study of $p_{T}$ spectra of light particles using modified Hagedorn function and cosmic rays Monte Carlo event generators in proton–proton collisions at $\sqrt{s}$ = 900 GeV

Abstract

Transverse momentum spectra ($p_T$) of charged particles including $\pi ^{\pm }$, $K^{\pm }$ and (anti-)protons measured by ALICE experiment in the $p_T$ range of 0.1–2.5 GeV/c and $|\eta |$ < 0.5 are studied in pp collisions at $\sqrt{s}$ = 900 GeV using modified Hagedorn function with embedded transverse flow velocity and are compared to the predictions of EPOS–LHC, Pythia, QGSJET and Sibyll models. We find that the average transverse flow velocity ($\beta _T$) decreases with increasing the mass of the particle, while the kinetic freeze-out temperature ($T_{0}$) extracted from the function increases with the particle’s mass. The former varies from (0.36 ± 0.01) c to (0.25 ± 0.01) c for $\pi ^{\pm }$ to protons, while the latter from (76 ± 6) MeV to (95 ± 5) MeV, respectively. The fit of the models predictions also yields the same values for $T_{0}$ and $\beta _T$ as the experimental data. The only difference is in the values of n and $N_0$ which yields different values for different models. The EPOS–LHC, Pythia and QGSJET models reproduce the data in most of the $p_{T}$ range for $\pi ^{\pm }$, EPOS–LHC and Sibyll for $K^{\pm }$ up to 1.5 GeV/c and EPOS–LHC for protons up to 1.6 GeV/c. The model simulations also reproduced the behavior of increasing average transverse momentum with mass reported by the ALICE experiment.