Recombination Model and Hadron Productions in Relativistic Nuclear Collisions

Anand, Ankit (2022) Recombination Model and Hadron Productions in Relativistic Nuclear Collisions. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Ankit Anand (17MS069)) 17MS069_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (10MB)

Abstract

The recombination of quark and anti quark is nowadays thought to be the dominant mechanism of hadron production in the large and intermediate x (low and intermediate pT ) region of spectra in high energy nuclear collisions. Several evidences in the support of the mechanism are argued. The observation of Baryon Puzzle and Leading Particle effect at RHIC (Relativistic Heavy Ion Collider, BNL, USA) made the study on recombination model more active after 2002. Recent observation of quark number scaling in observable v2, the elliptic flow coefficient of mesons and baryons hints towards the parton recombination model in low pT region. Recent observation in the pT spectra of Ω baryon and ϕ meson at mid-rapidity exhibit the constituent quark number scaling in a wide energy range from RHIC to LHC (Large Hadron Collider), which may indicate towards the Equal Velocity Combination(EVC) model. In this project, we present a comprehensive overview of recombination models. We use Equal Velocity Combination(EVC) model to understand some of the hadron productions. Using EVC model, we find the ratios of anti hadrons to hadrons, basically, ¯p/p, ¯Λ/Λ, ¯ Ξ/Ξ, ¯ Ω/Ω. We conclude that EVC works really well for non strange particles, and as the strangeness increases, the data are not well reproduced. We also point out the reasons as strangeness chemical potential is not properly included. In this report, we first study inelastic scattering and Deep Inelastic Scattering(DIS) to understand the parton model. Then we move to the Wigner functions to understand the hadron tomography. Wigner functions can be used as the kernel functions in the distributions of the hadrons. Finally, we study the recombination model and calculate the yield ratio of hadrons using EVC model. This project would guide us to work further in this direction to find pT spectra of hadrons and understand the meson productions with charm quarks and anti quarks as constituents.

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