Onset of deconfinement and critical point searches in NA61/SHINE experiment at SPS

<!--HTML-->Studies of the phase diagram of the strongly interacting matter is one of the hottest topics in high energy physics. While the transition from hadronic matter to Quark-Gluon Plasma (onset of deconfinement) is now rather uncontroversial, the difficulties in obtaining a unique and quantitative prediction of the QGP signal within the QCD theoretical framework remain and the scientific community still awaits the confirmation of an experimental observation of the critical endpoint of the transition line. In this talk, we will briefly report some recent results obtained by the NA61/SHINE Collaboration on those important issues. In particular, we will present the study of the proton-proton momenta intermittency phenomenon as a possible approach to the search of the QCD critical point. Up to now, an indication of second-order fluctuations has been observed in the freeze-out state of central Si+Si collisions at the NA49 Super Proton Synchrotron (SPS) experiment with beam energy √sNN=17.2 GeV. As its direct successor, the NA61/SHINE experiment is carrying on this search with the ability to scan the QCD phase diagram by varying the colliding nuclei (system size) and the collision energy.