German Title: Ein relativisches Diffusionsmodell für die Erzeugung geladener Hadronen in asymmetrischen Kollisionen

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Abstract

Charged-hadron production in asymmetric heavy-ion collisions at relativistic energies is investigated to enhance our understanding of the non-perturbative regime of Quantum Chromodynamics. We extend the three source Relativistic Diffusion model, a nonequilibrium-statistical model, by substituting the underlying phenomenological distributions with microscopic distributions based on the parton model. The mid-rapidity source is computed through gluon-gluon interactions using $k_T$-factorization within the framework of gluon saturation, while the two fragmentation sources are determined by quark-gluon interactions using hybrid-factorization and the parton distribution functions. The concept of the fragmentation sources is grounded in the phenomenon of baryon stopping but requires an extension through a diffusion process in rapidity space allowing to explain charged-hadron production. The final hadronisation stage is modeled based on parton-hadron duality. We calculate the pseudorapidity distributions for deuteron-gold (d-Au) at {$\sqrt{s_{NN}}=200$ GeV} and proton-lead (p-Pb) at {$\sqrt{s_{NN}}=5.02$ and $8.16$ TeV} numerically from solutions of the corresponding Fokker-Planck equation and compare them with experimental data from RHIC and LHC. In order to address non-analytical integrals and to utilize the numerical procedures required for the computations, a novel and self-developed $\Cpp$ program is utilized. The centrality-dependent distributions of produced charged hadrons obtained from the model calculations exhibit good agreement with the experimental data. The model calculations also highlight the significance of the fragmentation sources in comprehending the centrality dependence of produced hadrons, with particular emphasis on their pronounced influence in ultra-peripheral collisions.