Browsing by Author "Zhang, Yousen"

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    Search for and studies of Quark-Gluon Plasma via dynamics and productions of heavy quarks in proton-proton and heavy ion collisions at the LHC with CMS detector
    (2023-08-29) Zhang, Yousen; Li, Wei
    Heavy flavor quarks are sensitive to both the initial stage conditions and the subsequent in-medium evolution of nuclear collisions, and thus can provide insights to the inner workings of Quark-Gluon Plasma (QGP) in large ion collisions and the origin of the collectivity in small systems. In this thesis, data collected by the CMS detector at the Large Hadron Collider (LHC) from 2016 to 2018 are analyzed. The elliptic flow (v2{2}) and v2{4}) for charm mesons using two- and four-particle correlation technique in lead-lead collisions at a nucleon-nucleon center of mass energy 5.02 TeV is presented. The splitting between v2{4}/v2{2} of light charged particles and charm mesons is hinted in peripheral collisions, indicating that the potential energy loss fluctuations may become evident in a small QGP volume. Heavy flavor hadron production and their flow are also measured in proton-proton and proton-lead collisions, to search for tiny QGP in small systems. The charm and bottom v2{2} are measured through prompt and nonprompt D0 mesons in proton-proton at 13 TeV and proton-lead collisions at 8.16 TeV, as a function of transverse momentum (pT) and charged hadron multiplicity. The positive v2{2} signal is suggested in high multiplicity proton-proton collisions. When investigating multiplicity dependence, charm v2{2} shows diminishing trend towards smaller multiplicity. The hierarchy of charm and bottom v2{2} in low pT region is also indicated in proton-lead collisions. This suggests a potential mass dependence of v2{2}. The charm baryon-to-meson production ratio is also presented as a function of event multiplicity in proton-lead collisions at a nucleon-nucleon center of mass energy 8.16 TeV. Strikingly, no multiplicity dependence is observed for charm quarks in contrast to light strange quarks, though they show similar elliptic flow signal across a large range of multiplicity. Future measurements are necessary to understand the dynamics and hadronization of heavy quarks in small systems and heavy ion collisions. The first collision at the High Luminosity LHC (HL-LHC) is expected to be delivered in 2030. CMS Collaboration is preparing for its Phase-2 Upgrade to handle the challenge of a high beam intensity at the HL-LHC era. The physics impacts of CMS Phase-2 Upgrade at HL-LHC are presented, deciphering the nature of heavy flavor physics in QGP in an unprecedented way.