Production of Jets at RHIC and LHC

Abstract

The main subject of the habilitation thesis is study of jets produced in high-energy proton-proton (p+p) and nucleus-nucleus (A+A) collisions at the colliders RHIC at BNL and the LHC at CERN, respectively. Jets produced in p+p collisions serve not only to test predictions of quantum chromodynamics (QCD) in perturbative regime, but they are also an important reference measurement for A+A collisions in which conditions suitable for creation of a new state of QCD matter, the quark-gluon plasma (QGP), are expected to occur. Jets, collimated showers of particles, are created in hadronization of partons originating from hard scattering in the initial phase of the collision and are thus an ideal tool to peform tomography of QGP. Direct reconstruction of jets in large and fluctuating background of particles created in the heavy-ion collision is challenging and other methods such as studies of inclusive particle production with large transverse momentum or di-hadron correlations are explored as well. The habilitation thesis summarizes in three main chapters results achieved in stud ies of inclusive jet spectra, fragmentation functions and other jet properties in p+p collisions in the ALICE experiment. Next, results on di-hadron correlations including long-range correlations in pseudorapidity (the so called ridge) in A+A collisions in the ALICE and STAR experiments are discussed. Finally, results of inclusive jet spectra and their nuclear modification factors, jet radial profile, hadron+jet correlations, and baryon/meson ratios of strange particles in jets in A+A collisions in the ALICE and STAR experiments are presented. Wherever possible the results are compared with suitable theoretical models and other experiments.