arXiv subjects

G. R. Che

Publications and source records attributed to G. R. Che.

416 records · Page 24Linked to original sources

arXiv2021

Identified particle spectra in Pb-Pb, Xe-Xe and p-Pb collisions with Tsallis blast-wave model

We investigate the identified hadrons transverse momentum ($p_{\rm T}$) spectra in Pb-Pb (Pb-Pb, Xe-Xe, p-Pb) collisions at $\sqrt{s_{\rm NN}}=$ 2.76 (5.02, 5.44, 5.02) TeV in the framework of Tsallis-blast wave (TBW) model with a linear transverse velocity profile and with a constant velocity profile. In this model, the Tsallis temperature ($T$), the average radial flow velocity ($\langle β\rangle$) and the degree of non-equilibrium ($q$) of the system are common for all hadrons when a combined fit is performed to the $p_{\rm T}$ spectra of different particles at a given centrality. It is found that the model can describe the particle spectra well up to 3 GeV/c. For both profiles, the transverse flow velocity decreases from central to peripheral collisions while the non-extensive parameter $q$ exhibits the opposite behavior, indicating a more rapid expansion and less off-equilibrium of the system in more central collisions. Moreover, we observe that in central collisions $\langle β\rangle$ and $q$ ($T$) from the fit with the linear profile are smaller (is slightly larger) than those (that) with the constant profile, while in peripheral collisions $\langle β\rangle$, $T$ and $q$ from the former are compatible with those from the latter. We also derived and discussed the relation between the Tsallis temperature and the thermal temperature. In addition, to check whether a scenario of an early freeze-out of strange particles at the LHC exists, the particle spectra are investigated by grouping them into strange and non-strange hadrons. The combined fit gives an insight on the degree of non-equilibrium, the radial flow and the Tsallis temperature of the system at the kinetic decoupling. It provides a comparison between the results at different energies in the same collision system and the results in different collision systems at the same or similar energy.

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arXiv2019

Universal scaling of meson and baryon spectra in p-Pb collisions at 5.02 TeV

We systematically investigate the scaling property of mesons (pions and kaons) and baryons (protons, ${\rm Λ}$, ${\rm Ξ}$ and ${\rm Ω}$) transverse momentum ($p_{\rm T}$) spectra at different centrality classes (0-5$\%$, 5-10$\%$, 10-20$\%$, 20-40$\%$, 40-60$\%$, 60-80$\%$ and 80-100$\%$) in proton-lead collisions with center of mass energy per nucleon pair 5.02 TeV. In the low $p_{\rm T}$ region with $p_{\rm{T}}\leq $ 3.9 (3.1, 2.5, 2.7, 2.4 and 2.8) GeV/c, a universal scaling independent of the centrality is observed in the pion (kaon, proton, ${\rm Λ}$, ${\rm Ξ}$ and ${\rm Ω}$) spectra when a dilatation, $p_{\rm T}\rightarrow p_{\rm T}/K$, is applied. Here $K$ is a scaling parameter depending on the centrality class. We find that the rates at which ln$K$ changes with the logarithmic value of the average value of the number of participating nucleons, ln$\langle N_{\rm{part}}\rangle$, are stronger for baryons than those for mesons. In the high $p_{\rm T}$ region, there is a deviation from the scaling. The more peripheral the collisions are, the more obvious the violation of the scaling is. In the framework of the colour string percolation (CSP) model, we show that mesons and baryons are generated from the decay of clusters formed by strings overlapping in the transverse plane with the same size dispersion but with different mean size. The mean size of clusters for baryons is smaller than that of mesons. For the same hadrons at different centrality classes, the mean size of clusters decreases with the increase of centrality. The fragmentation functions for cluster decay are different for different hadrons, while they are universal for the same hadrons at different centrality classes. The universal scaling of the meson and baryon spectra in the low $p_{\rm T}$ region can be quantitatively understood with the CSP model at the same time.

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