Transizione di fase di deconfinamento in cromodinamica quantistica su reticolo nel regime di quark molto massivi

The focus of this work is to analyze the deconfinement phase transition taking place in QCD at high temperatures of the order of hundreds of MeV, or, equivalently, of 1012 Kelvin. These temperatures were realized in nature during the first few fractions of a microsecond after the Big Bang and influenced the expansion of the early Universe. Today, they are reproduced in a large, ongoing experimental programme of high-energy collisions of heavy nuclei. In particular, we wish to investigate the nature (and the order) of the deconfinement transition as a function of the quark masses and the temperature, focusing on the region of large quark masses. The work is divided as follows: After introducing the basic notions relevant for quantum field theory at finite temperature and the expected phase structure for different values of the quark masses, we describe how to discretize QCD on a lattice, focusing the attention on the HEX-smeared Wilson clover fermions action; then we explain the numerical tools and the data analysis techniques used in the simulations. In the fifth chapter the results are presented and in the last chapter, we will discuss some concluding remarks.