Identified particle spectra in Pb-Pb and p-Pb collisions with a modified Tsallis blast-wave model
With the recipe of the Tsallis-blast wave (TBW) model, we propose a modified version (mTBW) in which the transverse velocity profile does not depend on the radius of the emitting source. A combined fit is performed to the transverse momentum spectra of identified hadrons at a given centrality in Pb-Pb (Pb-Pb, p-Pb) collisions at $\sqrt{s_{\rm NN}}=$ 2.76 (5.02, 5.02) TeV with this modified model. It is found that the mTBW model can describe the particle spectra well up to 3 GeV/c. Moreover, we observe that the transverse flow velocity increases with centrality while the non-extensive parameter $q$ shows the opposite trend, indicating a more rapid expansion and less off-equilibrium of the system in central collisions. In addition, to check whether there is a possible early kinetic freeze-out of hadrons containing strange valence quarks at the LHC, the particle spectra are investigated by grouping them into strange and non-strange hadrons. The spectra of deuterons and $^{3}\rm He$ in Pb-Pb (p-Pb) collisions at 2.76 (5.02) TeV are also investigated in the framework of the mTBW model. The combined fit can provide insight on the degree of non-equilibrium, the radial flow and the temperature of the system at the kinetic freeze-out. Its usefulness lies in the ability to compare the results at different energies in the same colliding system and the results in different colliding systems at the same energy.