The global spin alignment of vector mesons has been observed by the STAR collaboration at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). It provides a unique opportunity to probe the correlation between the polarized quark and antiquark in the strongly coupled quark-gluon plasma (sQGP) produced in relativistic heavy ion collisions, opening a new window to...
We present a first-order dissipative spin hydrodynamic framework, where the spin chemical potential $\omega^{\mu\nu}$ is treated as the leading term in the hydrodynamic gradient expansion, i.e., $\omega^{\mu\nu}\sim \mathcal{O}(1)$. We argue that for the consistency of the theoretical framework, the energy-momentum tensor needs to be symmetric at least up to order $\mathcal{O}(\partial)$. We...
This work involves the study of the effects of rotation on the thermal diffusion properties of the QGP medium. The noncentral heavy ion collisions could possess finite angular momentum with a finite range of angular velocity, so, rotation gets induced in the produced medium. Like other extreme conditions, the rapid rotation can conspicuously alter various properties of the QGP medium including...
Strong magnetic fields are expected to exist in the early stages of heavy ion
collisions and there is also an increasing evidence that the energy dependence of the
cross-sections can strongly affect the dynamics of a system even at a qualitative level.
This led us to the current study where we developed second-order non-resistive
relativistic viscous magnetohydrodynamics (MHD) derived from...
In non-central heavy-ion collisions, substantial orbital angular momentum (OAM) is produced and transferred to the QGP and hadronic matter, leading to effects like spin polarization and the chiral vortical effect. Previous studies have explored the impact of OAM on electrical conductivity under a non-relativistic, globally rotating QGP. In this work, we have developed a relativistic framework,...
We present a systematic Bayesian analysis of Quark-Gluon Plasma (QGP) properties at finite baryon density using measurements of Au+Au collisions at the RHIC Beam Energy Scan program. The theoretical model simulates event-by-event (3+1)D dynamics of relativistic heavy-ion collisions with the state-of-the-art hybrid hydrodynamics and hadronic transport theory. We analyze the modelโs...
We derive a linearly stable and causal theory of relativistic third-order viscous hydrodynamics from the Boltzmann equation using the relaxation-time approximation. We employ a Chapman-Enskog-like iterative solution to the Boltzmann equation to obtain the viscous correction to the distribution function. Our derivation emphasizes the necessity of incorporating a new dynamical degree of freedom:...
Momentum transport in a medium is characterized quantitatively by its shear and bulk viscosities. The shear viscous coefficient ($\eta$) governs the momentum transport transverse to the hydrodynamic flow while its bulk counterpart ($\zeta$) does the same along the flow. In the context of quark gluon plasma (QGP), both $\eta$ and $\zeta$ are very important transport coefficients, controlling...
In recent years, analyses using RHIC-BES data have been actively conducted to explore the high baryon number density region in the QCD phase diagram. Meanwhile, even in high-energy collisions, such as RHIC and LHC energies, the presence of high baryon number density matter in the forward rapidity region has been suggested [1]. This implies that, in addition to the analysis of BES data, a...
Double-slit experiment at the femtometer scale with ALICE
In non-central heavy-ion collisions, large angular momentum is generated, leading to significant vorticity and subsequent spin polarization of particles with finite spin. The global polarization of $\Lambda$ and $\overline{\Lambda}$ hyperons ($P_\Lambda$ and $P_{\overline{\Lambda}}$), measured along the direction of global angular momentum, serves as an effective probe of both vorticity and...
This is a mini-review talk.
The matter produced in an ultra-relativistic heavy-ion collision, dubbed as the QGP, posses a temperature $10^5$ times that of Sun's core and survives for a very short time ($10^{-22}$ s), producing thousands of particles which exhibit collective motion described by some global observables, e.g. charged particle multiplicity($N_{ch}$), mean transverse momentum per particle ($[p_T]$), harmonic...
Extensive research at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) on Pb-Pb and Au-Au collisions have helped us develop and understand the properties of the quark-gluon plasma (QGP) in heavy-ion collisions. Recent investigation suggests that QGP-droplets may occur in small collision systems such as high-multiplicity pp collisions. O-O collisions are...
The strongly interacting matter created in relativistic heavy-ion collisions possesses several conserved quantum numbers, such as baryon number, strangeness, and electric charge. The diffusion process of these charges can be characterized by a diffusion matrix that describes the mutual influence of the diffusion of various charges. We derive the Kubo relations for evaluating diffusion...
Utilizing Zubarev's nonequilibrium statistical operator, we derive the second-order expression for the dissipative tensors in relativistic spin hydrodynamics, namely the rotational stress tensor ($\tau_{\mu\nu}$), boost heat vector ($q_\mu$), shear stress tensor ($\pi_{\mu\nu}$), and bulk viscous pressure ($\Pi$). The emergence of the first two terms, $\tau_{\mu\nu}$ and $q_\mu$, is attributed...
In heavy-ion collisions, the Chiral Magnetic Wave (CMW) is theorized to produce an electric quadrupole moment, leading to differences in elliptic flow between positively and negatively charged particles. This CMW signal can be detected by examining the correlation between charge-dependent elliptic flow and event charge asymmetry. This study focuses on the difference in covariance of elliptic...
The study of light nuclei production in relativistic heavy-ion collisions provides valuable insights into the properties of the dense, hot medium produced in these collisions, which is assumed to mimic conditions of the early universe. In this work, we analyze the production of light (anti-)nuclei, such as $d$, $\bar{d}$, $t$, and $^3\text{He}$, in the framework of the Hadron Resonance Gas...
We investigate the validity of the $\Lambda$ single-particle potential ($\Lambda$ potential) in dense matter that is based on chiral effective field theory (chiral EFT) that is sufficiently repulsive to solve the hyperon puzzle of neutron stars. We discuss that the model calculations with the $\Lambda$ potential are consistent with the $\Lambda$ hypernuclear spectroscopy [1] and the $\Lambda$...
Recent experiments involving isobar collisions of $^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr have been carried out at the Relativistic Heavy Ion Collider (RHIC). These studies aim to explore various phenomena, including the initial conditions of the collision process, baryon stopping, the chiral magnetic effect, and collective flow, which are all essential for...
One of the objectives of the STAR experiment is to study the phase transition from hadronic matter to Quark Gluon Plasma (QGP). This can be investigated by studying the collective flow of various particle types produced in heavy-ion collisions, particularly by testing whether the number of constituent quark (NCQ) scaling holds or breaks across different energies. Specifically, the elliptic...
We study multi-particle azimuthal correlations in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. We use initial conditions obtained from a Monte-Carlo Glauber model and evolve them within a viscous relativistic hydrodynamics framework that eventually gives way to a transport model in the late hadronic stage of the evolution. We compute the multi-particle symmetric and asymmetric cumulants and...
In this work, we address the problem of longitudinal spin polarization of ฮ hyperons produced in relativistic heavy-ion collisions. We employ a relativistic kinetic theory framework that incorporates spin degrees of freedom treated classically, combined with the freeze-out parametrization used in previous investigations. This approach allows us to include dissipative correctionsโstemming from...
In proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ = 13 TeV, gold-gold collisions at energies ranging from $\sqrt{s}$ = 7.7 GeV to 200 GeV, and lead-lead collisions at 2.76 TeV and 5.02 TeV, Bose-Einstein correlations of charged hadrons are examined across the entire multiplicity spectrum of reconstructed charged particles. The CMS data are then compared with results from...
The Hanbury Brown-Twiss (HBT) interferometry technique uses the two-particle correlation function to extract the three HBT radii, which measure the spatial and temporal dimensions of the particle emission source at freeze-out in heavy-ion collisions. In this study, we have employed a hybrid model combining hydrodynamic evolution with hadronic transport to simulate the collision dynamics in the...
The properties of the QGP medium produced in relativistic heavy-ion collisions can be explored using the directed flow ($v_{1}$) of the azimuthal angle distribution in momentum space. Hydrodynamic and nuclear transport models indicate that $v_{1}$ in the midrapidity region is sensitive to expanding participant matter during the early collision stages. Spectator nucleons influence the directed...
Transverse momentum fluctuations serve as a powerful tool for probing the properties and evolution dynamics of the system formed in high energy heavy-ion collisions. Momentum fluctuations are sensitive to the equation of state as well as to the bulk-viscosity of the QCD system. An observable known as $v_{0}(p_{T})$ which quantifies the momentum fluctuations has been suggested to measure in...
The underlying events (UE) in proton-proton (p$-$p) collisions encompass aspects of the interaction not attributed to the primary hard scattering, but arising from accompanying interactions of the rest of the proton.
Traditionally, UE studies involve defining topological regions relative to the leading particle in an event, with the transverse region being especially sensitive to UE...
We study the flavor dependance of the Chiral Magnetic Effect (CME) using two of the primary correlators used to characterize the charge separation effect. These are the correlator $\Delta\gamma $ and the correlator $R_{{\psi}_2}$. We use the AMPT (A Multiphase Transport Model) model to study the sensitivity of these correlators to two and three flavors of quarks. The AMPT model used has a...
Higgs Boson is characterized by J$^\pi$ = 0$^+$ and fundamentally forms the cosmos by interacting with other particles to impart mass in standard model discovered in 2012 at CERN. This study is focused on Z$\gamma$ channel of Higgs with branching ratio of $\beta(H \rightarrow Z\gamma) = (1.57 \pm 0.09) \times 10^{-3}$. Feynman diagram for Z$\gamma$ channel is similar to $\gamma$$\gamma$...
Photons as a probe of the strongly interacting matter in heavy ion collisions
Baryon dynamics from recent measurements on directed flow and polarisation
A baryon-rich medium is created in low-energy heavy-ion collisions. Using a hydrodynamic model that incorporates finite baryon density, we investigate the role of baryon stopping and diffusion in RHIC-BES phenomenology, focusing on the directed flow ($v_1$) observable. The $v_1$ splitting between protons and anti-protons has been an elusive observable for a long time, primarily due to improper...
The evolution of the strongly interacting medium formed in heavy-ion collison is modelled with multi-stage models. The models are driven by a large number of parameters that quantify the properties of the medium and the initial stage of the heavy-ion collision. The need to find model parameters which give the best description of the experimental data imposes a multidimensional optimization...
We use the Recombination Model to explain the hadron production data at center of mass energies 62.4, 200 and 2760 GeV at LHC and RHIC. The Recombination model considers the effective valence quark energy and momentum without taking the sea quarks and gluons explicitly into account. This model has been quite successful in explaining the larger-than-expected baryon-to-meson ratio and the...
One of the prime objectives of heavy ion collisions (HIC) is to find experimental evidence of the deconfinement phase transition from hadronic matter to quark-gluon plasma (QGP) in the reaction products of heavy ion collisions. Various hadronic models are used to study the investigation of the signature of QGP. One of the most successful models is the hybrid UrQMD-hydro model. It is a...
In relativistic nuclear collisions, spatial anisotropies characterized by initial eccentricity, triangularity, and higher-order eccentricities arise from the geometry of the collision and fluctuations in the initial energy density distribution. These spatial anisotropies subsequently manifest as momentum anisotropies in the final-state particles through the collective expansion of the hot and...
As recently observed by the STAR and ALICE collaborations, the global and local spin polarization of $\Lambda$-hyperons provides new insights into spin dynamics in heavy-ion collisions. There are various contributing factors that could be the source of hyperon polarization. However, among them, the vorticity field is widely considered as the primary source of particle polarization in heavy-ion...
