Scaling behavior of transverse momenta distributions in hadronic and   nuclear collisions
  It has been recently noticed that transverse momenta ($p_T$) distributions observed in high energy production processes exhibit remarkably universal scaling behavior. This is seen when they are in some suitable variable, replacing the usual $p_T$. On the other hand, it is also known that transverse momenta distributions in general follow a power-like Tsallis distribution, rather than an exponential Boltzmann-Gibbs, with a (generally energy dependent) nonextensivity parameter $q$. We now show that it is possible to choose a suitable variable such that $p_T$ distributions of particles produced in proton-proton interactions in a wide energy range can be fitted by the same Tsallis distribution (with the same, energy independent, value of the $q$-parameter). Similar scaling behavior in nucleus-nucleus collisions is also observed. The possible dynamical origin of the q parameter used in these fits will be discussed. 
M. Rybczynski, Z. Wlodarczyk and G. Wilk
hep-ph