Search of critical effects in NA61/SHINE

Abstract

NA61/SHINE is a multi-purpose experiment to study hadron-proton, hadron-nucleus and nucleus-nucleus collisions at the CERN Super Proton Synchrotron (SPS). The experiment performs unique measurements for the physics of strong interactions as well as important reference measurements for neutrino and cosmic-ray physics. The primary goals of the experiment are the study of the onset of deconfinement and the search for the critical point of the strongly interacting matter, to uncover the mechanism of thermalisation and to test the validity of statistical models. For this purpose, a two-dimensional scan was performed by varying the beam momentum (13$A$--158$A$~GeV/$c$) and the size of colliding systems (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb). In this contribution, we present recent NA61/SHINE results on the search for critical effects in spectra and fluctuations. We see no clear indication for the onset of deconfinement for intermediate colliding systems. Nevertheless, results from p+p interactions on spectra and onset of deconfinement reveal anomalous behaviour in proximity to transition energy. In fluctuation analysis of collisions of medium size nuclei at the top SPS energy, no prominent signal of critical point was observed.