We demonstrate that the early stages of the bottom-up thermalization scenario [1] are well described by the adiabatic hydrodynamization framework, thus providing novel analytic results on the thermalization process of QCD in a heavy ion collision. These results provide an intuitive explanation of why a gas of quarks and gluons can relax so quickly towards equilibrium, and provide a starting...
High-energy heavy-ion collisions offer a unique and precise way to probe nuclear structures by providing a snapshot of the nuclear distribution at the time of the collision, which is complementary to low-energy nuclear physics experiments.
In this talk, we present a comprehensive scan of flow observables, including anisotropic flow coefficients, nonlinear flow modes, and normalized...
The multiplicity distribution measures the probability of obtaining a certain number of particles in a given collision and is one of the first observables measured in data at each new collision type and center of mass energy. It is relevant since is one of the fundamental observables to describe the global properties of the interactions and is sensitive to non-linear QCD evolution in the...
Multiplicity distributions of primary charged particles are sensitive to non-linear QCD evolution in the initial state. We present the distributions in various pseudorapidity ranges in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV. Charged particles are reconstructed using the Inner Tracking System that has been upgraded for Run3 at LHC and is operation starting in 2022. The data are...
In heavy ion collisions, the initial state geometry plays a crucial role in determining final state observables such as elliptic flow $v_2$ and radial flow reflected by event-wise average transverse momentum $[p_{\rm T}]$. The initial state geometry is influenced by several nuclear shape parameters, including quadrupole deformation (β), triaxiality (γ) [1], nuclear radius (r), and skin depth...
The early stage of high-energy nuclear collisions is dominated by strong gluon fields called the evolving Glasma. This stage can be probed by heavy quarks (HQs), charm and beauty, since they are produced almost immediately by hard scatterings. We study the propagation of HQs in the evolving Glasma fields, by solving the relativistic kinetic equations that couple the HQs to the fields...
The collective properties of nuclear structure, such as radii and deformations, leave distinct signatures in the initial and consequently final stages of relativistic heavy-ion collisions. Collisions of deformed nuclear enhance the fluctuations of harmonic flow coefficients $v_n$ and event-wise mean transverse momentum $[p_T]$, therefore offering a viable approach to establish clear...
In this poster, we present the ATLAS measurement of the centrality dependence of the dijet per-event yield at center-of-mass energy 8.16 TeV in $p$+Pb collisions. The per-event yield of unfolded dijet pairs is presented in terms of kinematic variables that allow for full characterization of the partonic scattering system, i.e. the average $p_{\mathrm{T}}$ of the dijet, $p_{\mathrm{T,Avg}} =...
The jet quenching parameter $\hat q$ encodes jet medium interactions during the entire quark-gluon plasma evolution in heavy-ion collisions. For a long time, the impact of pre-equilibrium stages has not been properly treated in jet quenching calculations, although recent studies find large values for $\hat q$ in the earliest (glasma) stage. For the first time, we show that QCD kinetic theory...
We present a Monte-Carlo implementation of the EKRT initial-state model (MC-EKRT) [1]. Our new MC-EKRT event generator is based on collinearly factorized, dynamically fluctuating pQCD minijet production, supplemented with a saturation conjecture that controls the low-$p_T$ particle production. Previously, the EKRT model has been very successful in describing low-$p_T$ observables at...
Constraining the three-dimensional structure of the initial state and transport properties of the Quark-Gluon Plasma (QGP) at different temperatures ($T$) and baryon chemical potentials ($\mu_B$) is a critical objective of heavy-ion programs at RHIC and the LHC. This work presents comprehensive measurements on both topics for various event-shape and centrality selections of Au+Au collisions at...
The pseudorapidity density of charged particles with different values of minimum transverse momentum ($p_\mathrm{T}$) thresholds of 0.15, 0.5, 1, and 2 GeV/c is measured in pp collisions at $\sqrt{s} =$ 5.02 and 13 TeV with the ALICE Run 2 set-up. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity ($\eta$) within ±0.8 and...
The study of strongly interacting matter under external conditions (such as high temperatures and/or baryon densities) provides unique insights into its fundamental theory, Quantum Chromodynamics (QCD). A nonzero angular momentum imposed on a QCD system can bring rich and intriguing phenomena, with the proton spin structure being a perfect example. A much larger QCD system with substantial...
Universality is omnipresent when certain classes of microscopic theories are coarse-grained into effective macroscopic descriptions. Hydrodynamic theories are such macroscopic descriptions in long-wavelength, low-frequency limits of many quantum field theories. On the phenomenological side, hydrodynamics not only serves as a successful macroscopic description of the Quark-gluon plasma (QGP) in...
We present a new study of two-particle correlations as extracted with the CMS experiment in 8.16 TeV proton-lead (pPb) events with large rapidity gaps in the proton going region. Recent comparisons of the cross sections of such events measured in CMS as a function of the rapidity gaps (i.e., regions devoid of any particle activity) with several generators suggest that such events have...
