Study of Inclusive b-Jet Production in ALICE Experiment at LHC

The relativistic heavy-ion collisions produce a hot and dense deconfined state of QCD matter, called quark-gluon plasma (QGP). The characterization of this deconfined QCD matter is important to understand the fundamental thermodynamic and transport properties of it and how the constituents of it interact among themselves. Amongst many, one of the crucial probes to characterize the QCD matter is the heavy quark jets (charm jets, bottom jets (b-jets)), mainly produced in the primordial hard scatterings in the collisions. The measurement of b-jet production in p-Pb collisions addresses several key points like pQCD production cross-section, cold nuclear matter effect and base line for nucleus-nucleus collisions. Apart from these, the b-jet measurement in p–Pb collisions is interesting to investigate the interplay between heavy quark jets and the nuclear environment. The main focus of the thesis is to measure the bottom quark jet (b-jet) production in p-Pb collisions at √sNN = 5.02 TeV in the ALICE experiment at the LHC. We use the anti-kT jet finding algorithm with jet resolution parameter R = 0.4, as implemented in the FastJet package. The secondary vertices are searched within the reconstructed jets and the properties (large decay lengths) of the secondary vertices are used to tag the b-jets among other flavor jets. In order to obtain the b-jet yields, the tagged jets yields are corrected for tagging efficiency and purity, obtained from Monte Carlo simulations and data driven approach. Finally the b-jet yields are corrected for detector effects using Unfolding method and the systematic uncertainties are estimated. The measured pT-differential production cross section for b-jets in p-Pb collisions at √sNN = 5.02 TeV has been compared with NLO pQCD calculations (POWHEG+PYTHIA). The measurement of b-jet cross-section agrees well with the NLO pQCD calculations within the experimental and theoretical uncertainties. Apart from the experimental measurements, the thesis includes the phenomenological study of heavy quark propagation and chromo-electromagnetic field fluctuations present in the QGP medium. We estimate the effect of the color field fluctuations on the heavy quark transport coefficients (drag and diffusion coefficient), shear viscosity to entropy density ratio (η/s) of the QGP; and nuclear modification factors (RAA) of open charm (D mesons), open beauty mesons (B mesons) and hidden charm (J/Ψ) mesons. We find that these fluctuations result a reduction of the drag and diffusion coefficients of heavy quarks, as these fluctuations cause heavy quarks to gain energy. We also observe that the value of η/s of the QGP medium increases with the inclusion of these fluctuations and make the calculation of η/s closer to the value obtained in lattice QCD (LQCD) and functional renormalization group calculations. The calculated RAA of the heavy-flavor mesons can describe the measured RAA of D-mesons and B-mesons at the CMS and the ALICE experiments within their uncertainties, when the effect of these fluctuations is included along with the energy loss processes.