Conveners
Collective Dynamics: (1)
- Jun Takahashi (University of Campinas UNICAMP (BR))
Collective Dynamics: (2)
- James Lawrence Nagle (University of Colorado Boulder)
Collective Dynamics: (3)
- Marco Van Leeuwen (Nikhef National institute for subatomic physics (NL))
Directed and elliptic flow ($v_{1}$, $v_{2}$) are sensitive to the dynamics of heavy-ion collisions at the early stage of the system evolution and the equation of state (EoS) of the medium. The $v_1$ slope ($dv_1/dy$) at mid-rapidity of net-baryons is expected to be sensitive to the first-order phase transition. Also, triangular flow ($v_3$) provides valuable information on the initial...
Most of our experimentally-driven knowledge about the early stages of a heavy-ion collision comes from analysis of measurements made near mid-rapidity. However, much information about the dynamics is encoded in rapidity-dependent behavior, and there exists a large amount of experimental data available to constrain this rapidity dependence. To leverage this information, we perform a systematic...
Using a (3+1)-dimensional hybrid framework with parametric initial conditions, we study the rapidity-dependent directed flow $v_1(y)$ of identified particles, including pions, kaons, protons, and lambdas in heavy-ion collisions. Cases involving Au+Au collisions are considered, performed at $\sqrt{s_{\rm NN}}$ ranging from 7.7 to 200 GeV. The dynamics in the beam direction is constrained using...
The $f_0(980)$ is a candidate exotic hadron, first observed by $\pi\pi$ scattering in the 1970โs. Its configuration still remains controversialโ it can be a normal $s\bar{s}$ meson, a tetraquark $s\bar{s}q\bar{q}$ state, a $q\bar{q}g$ hybrid, or a $\mathrm{K}\bar{\mathrm{K}}$ molecule. Relativistic heavy ion collisions are in a unique position to identify the $f_0(980)$ quark content by the...
Intermediate pT jets (minijets) are created by initial hard scatterings in heavy-ion collision experiments. They can constitute a significant portion of the particle multiplicity but do not lend themselves to hydrodynamic treatment as their transverse momenta are larger than the typical saturation scale of the bulk matter.Their orientation is independent of the underlying event and they can...
The early dynamics in heavy-ion collisions involves a rapid, far from equilibrium evolution. This early pre-equilibrium stage of the dynamics can be modeled using kinetic equations. The effect of this pre-equilibrium stage on final observables derived from transverse momenta of emitted particles is negligible. Therefore, the kinetic equations in the relaxation time approximation for a...
We simulate the space-time dynamics of high-energy collisions based on a microscopic kinetic description, in order to determine the range of applicability of an effective description in relativistic viscous hydrodynamics [1,2]. We find that hydrodynamics provides a quantitatively accurate description of collective flow when the average inverse Reynolds number $\mathrm{Re}^{โ1}$ is sufficiently...
The formation of light nuclei in heavy-ion collisions can be explained by two models: the thermal model and the coalescence model. The thermal model proposes that light nuclei originate from a thermal source where they are in equilibrium with other particles in the fireball. However, due to their low binding energies, the formed nuclei are unlikely to survive the high-temperature conditions of...
This talk presents a measurement of higher order flow harmonics with order number up to 10 in lead-lead (PbPb) collisions at $\sqrt{s_{_{\mathrm{NN}}}} = 5.02$~TeV, using data collected by the CMS experiment. Higher order flow harmonics probe the initial geometry of heavy ion collisions as well as the viscous damping of flow coefficients during the evolution of the quark-gluon plasma (QGP). By...
It is a fundamental question to understand what is the effective carrier of conserved quantum charges inside a proton at high energy. The net baryon and electric charge rapidity distributions in relativistic heavy-ion collisions can elucidate how different
conserved charges are transported along the longitudinal direction during the collision. Recent preliminary measurements in isobar...
We report the first direct evidence of thermalization of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collision, by studying the fluctuation of mean transverse momentum per particle ($\langle p_t \rangle$) in ultra-central Pb+Pb collision. The recent experimental data from the ATLAS collaboration at the Large Hadron Collider (LHC), provides measurement of variance of...
This talk presents a measurement of longitudinal decorrelation in $pp$ collisions with ATLAS. The deposited energy in the transverse $(x,y)$ plane is expected to vary, depending on the longitudinal $(z)$ slice examined, which is correlated with the rapidity of the produced particles. Thus, particles from different rapidity slices will have flow vectors that differ in magnitude and orientation...
Deciphering the process of hadronization has long been a formidable challenge, in part due to its non-perturbative nature. Over the years, various phenomenological models have emerged, all attempting to unravel the complexity of hadron production. Despite their different theoretical foundations, many of these models successfully account for the average yield of hadrons. This has spurred the...
In heavy-ion collisions, the measurements of anisotropic flow coefficient ($v_n$) offer insights into collective hydrodynamic expansion and transport properties of the produced medium at higher collision energies, while they are sensitive to the compressibility of the nuclear matter and nuclear equation of state at lower collision energies. The second phase of the Beam Energy Scan program...
Due to large pressure gradients at early times, standard hydrodynamic model simulations of relativistic heavy-ion collisions do not become reliable until $O(1)$ fm/$c$ after the collision. To address this one often introduces a pre-hydrodynamic stage that models the early evolution microscopically, typically as a conformal, weakly interacting gas. In such an approach the transition from the...
Studying the production and collectivity of light and hyper-nuclei in high-energy nuclear collisions in the high baryon density region can help us understand how they form and how hyperons interact with nucleons under finite pressure.
In this talk, we will present the first results on the energy dependence of directed flow $v_1$ of light and hyper-nuclei (p, d, $^3$He, and $\Lambda$,...
We present a novel multi-fluid approach to simulate heavy-ion collisions in the region of RHIC Beam Energy Scan and FAIR experiments. This region of collision energies from few to few tens of GeV is particularly interesting for the exploration of dense baryon matter and search of the critical point of QCD. However, fluid-dynamical modelling here poses notable challenges. Contraction of the...
We perform a systematic study on the local and global spin polarization of $\Lambda$ and $\overline{\Lambda}$ hyperons in relativistic heavy-ion collisions at beam energy scan energies via the (3+1)-dimensional CLVisc hydrodynamics model with AMPT and SMASH initial conditions. Following the quantum kinetic theory, we decompose the polarization vector as the parts induced by thermal vorticity,...
Characterization of the quark--gluon plasma (QGP) created in ultrarelativistic heavy-ion collisions requires identifying observables sensitive to the different phases of the collision. Previous studies have shown that measurements of the azimuthal anisotropic flow and the complex interplay between its harmonics can provide valuable information on the QGP transport properties.
In this talk,...
