From elementary particles to stars

The 50th anniversary of National Institute of Physics and Nuclear Engineering (IFIN-HH) coincides with half a century from the discovery of relativistic heavy ions in the primary cosmic radiation. Therefore, an analysis of connections between Particle Physics and Cosmology seems to be indicated at this anniversary. The Relativistic Nuclear Physics could be a bridge between the two fields. Important information on the Universe evolution after Big-Bang, can be obtained in ultrarelativistic nuclear collisions. To compare the processes following the Big Bang with those of quark-gluon plasma formation, expected at collider energies, it is necessary to know the thermodynamic conditions for each stage as well as the time evolution of the systems. In this work, some comparisons of the experimental results and simulations on thermodynamic parameters obtained in relativistic and ultrarelativistic nuclear collisions are discussed and compared with some recent cosmological observations. The existence of similar values of the thermodynamic parameters for equivalent moments in the evolutions of the two systems could be an important tool in a deeper understanding of the Universe. (authors)