High-pT processes in proton- and deuteron-nucleus collisions at TeV energies are the best presently available way to study the partonic structure of the nucleus in a high-density regime. Jet production over a wide range of phase space can significantly constrain the current knowledge of nuclear parton distribution functions (nPDFs), which are substantially less well understood than the corresponding PDFs in protons and which have only recently begun to be treated in a spatially-dependent way. An accurate knowledge of nPDFs is crucial for a definitive control of perturbative processes in a cold nuclear environment, since high-pT probes are used to quantitatively investigate the hot QCD matter created in ultrarelativistic nucleus-nucleus collisions. Furthermore, jets from low Bjorken-x partons can probe the transition from the dilute to saturated nuclear regimes.

The jet production in proton-proton, proton-nucleus and nucleus-nucleus collisions at relativistic and ultrarelativistic energies using the HIJING is studied and discussed. We analyzed the distributions of multiplicity of secondary charged particles, their pseudorapidity, rapidity and the transverse mass as a function of the number of jets. These parameters are used to estimate energy density and temperature of the hadronic matter to get the signal about QGP formation. For ultrarelativistic energy we considered pp at 14 TeV, PbPb at 5.5 TeV, pPb at 8.8 TeV and ArAr at 6.3 TeV, same as in ALICE and also at 25.0 GeV as relativistic energy. We obtained some insights about some properties of jets and their influences on the characteristics of the secondary particles produced in relativistic and ultrarelativistic hadronic collisions. In this text the background information about the jet production is presented in chapter 1. Chapter 2 contains description of the HIJING parameters. Chapter 3 is a description of the ALICE detectors. The results obtained by using the HIJING for pp, pA and AA interactions are presented and discussed in Chapter 4. Chapter 5 summarizes the conclusions.

Here, we develop a new formalism to describe the inclusive production of small radius jets in heavy-ion collisions, which is consistent with jet calculations in the simpler proton-proton system. Only at next-to-leading order (NLO) and beyond, the jet radius parameter R and the jet algorithm dependence of the jet cross section can be studied and a meaningful comparison to experimental measurements is possible. We are able to consistently achieve NLO accuracy by making use of the recently developed semi-inclusive jet functions within Soft Collinear Effective Theory (SCET). Additionally, single logarithms of the jet size parameter [alpha]$n\atop{s}$lnnR leading logarithmic (NLLR) accuracy in proton-proton collisions. The medium modified semi-inclusive jet functions are obtained within the framework of SCET with Glauber gluons that describe the interaction of jets with the medium. We also present numerical results for the suppression of inclusive jet cross sections in heavy ion collisions at the LHC and the formalism developed here can be extended directly to corresponding jet substructure observables.