Comprehensive Study of Identified Hadron Spectra, π± , K± and p(p̄) in PbPb Collisions at √sNN= 5.36 TeV with the ALICE Detector at CERN

In ultra-relativistic heavy-ion collisions, the Large Hadron Collider (LHC) at CERN recreates, for a brief instant, the conditions that existed microseconds after the Big Bang. Under such extreme conditions, ordinary nuclear matter transitions into a de- confined state of strongly interacting quarks and gluons, the fundamental degrees of freedom of Quantum Chromodynamics (QCD), forming what is known as the Quark Gluon Plasma (QGP). One of the central goals of modern nuclear physics and a primary objective of the ALICE (A Large Ion Collider Experiment) experi- ment at the LHC, is to comprehend the properties of this primordial state of matter, including its evolution, expansion, and eventual hadronization into the particles we observe. With its exceptional tracking and particle identification (PID) capabilities, ALICE offers a unique opportunity to measure identified hadron spectra and ex- plore the microscopic characteristics of this medium. By investigating how matter responds to heating to trillions of degrees and com- pression to energy densities significantly higher than those found in atomic nuclei, this thesis presents a precision study of identified hadron production, specifically pions (π ± ), kaons (K ± ), and protons (p, p̄) in lead–lead (PbPb) collisions at a center √ of mass energy per nucleon pair of sNN = 5.36 TeV. A dedicated analysis frame- work was developed to extract particle yields by employing information from the Time Projection Chamber (TPC) and Time of Flight (TOF) detectors, enabling robust particle species separation over a broad range of transverse momenta (pT ) and colli- sion centralities. Exploiting the high-stat dataset from the LHC Run 3, high precision pT spectra across several centrality intervals are obtained by reconstructing, calibrating, and correcting raw particle yields. Each stage of the analysis, from PID using TPC and TOF signals to the evaluation of efficiency and acceptance corrections was rigorously validated to ensure stability and reliability throughout the entire pT range. The cor- rected spectra provide a quantitative foundation for future physics studies and serve as essential benchmarks for theoretical models describing the transport properties, collective dynamics, and hadronization mechanisms of strongly interacting QCD matter. In addition to the PbPb study, this thesis applies the same analysis strategy to oxy- √ gen–oxygen (OO) collisions at sNN = 5.36 TeV, recorded during the first light-ion run at the LHC. As the smallest genuine nucleus–nucleus system ever collided at the LHC, OO provides a unique link between proton-induced (pp, p–Pb) and heavy- ion (Xe–Xe, Pb–Pb) reactions. Using identical reconstruction and correction proce- dures, the OO spectra allow a direct and unbiased comparison of particle production across a wide range of system sizes. When the results are expressed as a function of charged-particle multiplicity (dNch /dη), the OO measurements align smoothly with established PbPb trends, reinforcing the emerging picture that many bulk observ- ables scale primarily with final-state multiplicity rather than the mass number of the colliding nuclei. By combining PbPb and OO results, this thesis provides new in- sight into final-state collectivity, strangeness production, baryon enhancement, and kinetic freeze-out dynamics in light-ion collisions.