Prabat Ranjan Pujahari

We report studies of charge-independent (CI) and charge-dependent (CD) two-particle differential-number correlation functions, R2Δη,Δφ, and transverse momentum (pT) correlation functions, P2Δη,Δφ, of charged particles in s=2.76TeV pp collisions with the PYTHIA and HERWIG models. Model predictions are presented for inclusive charged hadrons (h±), as well as pions (π±), kaons (K±), and (anti-)protons (p/p) in the ranges 0.2

The observation of a wide variety of physical phenomena in the context of the formation of a strongly interacting QCD matter in heavy-ion nuclear collisions at the LHC has drawn significant attention to the high energy heavy-ion physics community. The appearance of a varieties of similar phenomena as in heavy-ion in the high multiplicity proton-proton and proton-nucleus collisions at the LHC energies has triggered further investigation to understand the dynamics of particle production mechanism in a highly dense and small QCD medium. The CMS collaboration uses many different probes in these studies ranging from the particle production cross section to multi-particle correlations. In this proceeding, I report a few selected recent CMS results from the small systems with the main focus on the measurement of collective phenomena in high multiplicity pp and pPb collisions.

The discovery of hot and dense quantum chromodynamics (QCD) matter, known as Quark-Gluon Plasma (QGP), is an essential milestone in understanding the finite temperature QCD medium. Experimentalists around the world collect an unprecedented amount of data in heavy ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and at the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland. The experimentalists analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe just after the Big Bang. Recent advancements in theory, experimental techniques, and high computing facilities help us to better interpret experimental observations in heavy ion collisions. The exchange of ideas between experimentalists and theorists is crucial for the characterization of QGP. The motivation of this first conference, named Hot QCD Matter 2022 is to bring the community together to have a discourse on this topic. In this paper, there are 36 sections discussing various topics in the field of relativistic heavy ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This paper begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP. Finally, it concludes with an overview of experimental results.

We presented a study of charge-independent (CI) and charge-dependent (CD) two-particle differential number correlation functions R2 and transverse momentum correlation functions P2 in pp collisions at s=2.76 TeV with the PYTHIA and HERWIG models.Calculations were presented for unidentified hadrons in three pT ranges 0.2 < pT≤ 2.0 GeV/c, 2.0 < pT≤ 5.0 GeV/c, and 5.0 < pT≤ 30.0 GeV/c.PYTHIA and HERWIG both qualitatively reproduce the near-side peak and away-side ridge correlation features reported by experiments.At low pT, both models produce narrower near-side peaks in P2 correlations than in R2 as reported by the ALICE collaboration in p–Pb and Pb–Pb collisions.This suggests that the narrower shape of the P2 near-side peak is largely determined by the pT dependent angular ordering of hadrons produced in jets.Both PYTHIA and HERWIG predict widths that decrease with increasing pT.Widths extracted for P2 correlators are typically significantly narrower than those of the R2 counterparts [1].