Tsallis statistics approach to the transverse momentum distributions in p-p collisions

Transverse momentum distributions of negatively charged pions produced in p-p interactions at beam momenta 20, 31, 40, 80 and 158 GeV/c are studied using the Tsallis distribution as a parametrization. Results are compared with higher energies data and changes of parameters with energy are determined. Different Tsallis-like distributions are compared.Comment: 6 pages, 9 figure

System size dependence of the log-periodic oscillations of transverse momentum spectra

Recently the inclusive transverse momentum distributions of primary charged particles were measured for different centralities in $Pb+Pb$ collisions. A strong suppression of the nuclear modification factor in central collisions around $p_T \sim 6-7$ GeV/c was seen. As a possible explanation, the hydrodynamic description of the collision process was tentatively proposed. However, such effect, (albeit much weaker) also exists in the ratio of data/fits, both in nuclear $Pb+Pb$ collisions, and in the elementary $p+p$ data in the same range of transverse momenta for which such an explanation is doubtful. As shown recently, in this case, assuming that this effect is genuine, it can be attributed to a specific modification of a quasi-power like formula usually used to describe such $p_T$ data, namely the Tsallis distribution. Following examples from other branches of physics, one simply has to allow for the power index becoming a complex number. This results in specific log-periodic oscillations dressing the usual power-like distribution, which can fit the $p+p$ data. In this presentation we demonstrate that this method can also describe $Pb+Pb$ data for different centralities. We compare it also with a two component statistical model with two Tsallis distributions recently proposed showing that data at still larger $p_T$ will be sufficient to discriminate between these two approaches.Comment: 6 pages, 8 figures. Contibution to the XLIV International Symposium on Multiparticle Dynamics proceeding

On wounded constituents in nuclear collisions

In this talk we summarize the main results of our recent paper, Phys. Rev. C94, 014902, where we explore predictions of the wounded quark model for particle production and the properties of the initial state formed in ultra-relativistic collisions of atomic nuclei.Comment: 5 pages, 3 figures. Talk at XLVI International Symposium on Multiparticle Dynamics given by M