Raghunath Sahoo

• Professor at Indian Institute of Technology Indore India

Long-range multi-particle correlations in heavy-ion collisions have shown conclusive evidence of the hydrodynamic behavior of strongly interacting matter and are associated with the final-state azimuthal momentum anisotropy. In small collision systems, azimuthal anisotropy can be influenced by the hadronization mechanism and residual jet-like corre...

In this study, we investigate the influence of deconfined QCD matter on quarkonium spin alignment in ultra-relativistic heavy-ion collisions. We estimate the spin alignment of charmonium ($J/\psi$, and $\psi$(2S)) and bottomonium ($\Upsilon$(1S), and $\Upsilon$(2S)) states by calculating the energy eigenvalues in a thermal rotating medium. We solve...

Event classifiers are the most fundamental observables to probe the system size and event topology of high-energy collisions. Significant progress has been made to establish suitable event classifiers to probe different physics processes occurring in elementary $e^{+}e^{-}$ to heavy-ion collisions in a range of center of mass energies. One of the m...

This study presents a novel approach by integrating vorticity, viscosity, and the magnetic field within a unified second-order relativistic viscous hydrodynamics framework. Using the developed framework, we estimate the global spin polarization of hyperons by analyzing vorticity evolution at the freeze-out hypersurface. The intricate interplay bet...

The global and local (longitudinal) spin polarization measurements of Λ ( Λ¯ ) hyperons by STAR and ALICE Collaborations open up an immense interest in investigating the spin polarization dynamics in heavy-ion collisions. Recent studies suggest the transverse component of the vorticity field is responsible for the global spin polarization. In contr...

The recent observation of global spin polarization of hyperons and the spin alignment of vector mesons create remarkable interest in investigating the particle polarization in the relativistic fluid produced in heavy-ion collisions at GeV/TeV energies. Among other sources of spin polarization phenomena, the Debye mass of a medium plays a crucial ro...

The Lagrangian for strongly interacting and rotating quark matter is modified with the inclusion of the spinorial connections, which in turn affect the thermodynamic equation of state and transport properties of the medium. In this work, we investigate the transport properties of quark matter under finite rotation, focusing specifically on electric...

Anisotropic flow and fluctuations are sensitive observables to the initial state effects in heavy ion collisions and are characterized by the medium properties and final state interactions. Using event-shape observables, one can constrain the probability distributions of anisotropic flow coefficients, thus reducing the linear and nonlinear contribu...

The hot and dense hadronic medium formed during the heavy-ion collisions at the Relativistic Heavy Ion Collider and Large Hadron Collider energies can show thermoelectric effects in the presence of temperature gradients and nonzero baryon chemical potential. In this article, we study the thermoelectric coefficients of an interacting hot and dense h...

The hadronic phase and its dynamics in relativistic heavy-ion collisions are topics of immense discussion. The hadronic phase contains various massive hadrons with an abundance of the lightest hadron, i.e., π-mesons (pions). In this paper, we consider that pions are in the thermal equilibrium in the hadronic phase and use second-order viscous hydro...

In this contribution, we use machine learning (ML) based models to separate the prompt and non-prompt production of heavy flavour hadrons, such as $D^0$ and J/$\psi$, in proton-proton collisions at LHC energies. For this purpose, we use PYTHIA~8 to generate events, which provides a good qualitative agreement with experimental measurements of charm...

In this paper, we explore the effects of the presence of clustered nuclear structure of $^{16}O$ in the final state elliptic flow fluctuations through $^{16}O$-$^{16}O$ collisions at $\sqrt{s_{\rm NN}}=7$ TeV within a hybrid model, IPGlasma+MUSIC+iSS+ UrQMD. We compare the results of elliptic flow fluctuations using $\alpha$-clustered nuclear struc...

The study of symmetry plane correlations (SPCs) can be useful in characterizing the direction of the anisotropic emission of produced particles in the final state. The study of SPCs provides an independent method to understand the transport properties of the system formed in heavy-ion collisions. Similar to anisotropic flow coefficients, which are...

The present investigation reports the design and development of an advanced material with a high figure of merit (FoM) for beampipe applications in particle accelerators by bringing synergy between computational and experimental approaches. Machine-learning algorithms have been used to predict the phase(s), low density, and high radiation length of...

In relativistic heavy-ion collisions, the formation of a deconfined and thermalized state of partons, known as quark-gluon plasma (QGP), leads to enhanced production of strange hadrons in contrast to proton-proton ( p p ) collisions, which are taken as baseline. This observation is known as strangeness enhancement in heavy-ion collisions and is con...

The hot and dense hadronic medium formed during the heavy-ion collisions at the RHIC and LHC energies can show thermoelectric effects in the presence of temperature gradients and non-zero baryon chemical potential. In this article we study the thermoelectric coefficients of an interacting hot and dense hadron gas using the relativistic Boltzmann tr...

Recent observations of quark-gluon plasma (QGP) like signatures in high-multiplicity proton-proton (pp) collisions, have compelled the heavy-ion physics community to re-examine small collision systems for proper baseline studies. Event shape-based studies in pp collisions have succeeded to a certain extent in identifying the rare events mimicking s...

In ultra-relativistic collisions of nuclei at the Large Hadron Collider, the created QCD environment rapidly changes, leading to a non-adiabatic evolution of the quantum states involved. Considering this, we first examine the pre-equilibrium state of QCD matter and its effect on the initially produced charmonium using a temperature-independent Hami...

We study the diffusion properties of an interacting hadron gas and evaluate the diffusion coefficient matrix for the baryon, strange, electric, and charm quantum numbers. For the first time, this study sheds light on the charm current and estimates the diffusion matrix coefficient for the charmed states by treating them as a part of the quasitherma...

We developed a deep learning feed-forward network for estimating elliptic flow (v2) coefficients in heavy-ion collisions from RHIC to LHC energies. The success of our model is mainly the estimation of v2 from final state particle kinematic information and learning the centrality and the transverse momentum (pT) dependence of v2 in wide pT regime. T...

In this work, we observed that quarkonia traversing through the medium does not carry the same temperature as the medium due to the relativistic Doppler shift effect. The implicit temperature of the particle depends on its velocity, and here we showed how quarkonia velocity (vQ) or transverse momentum (pT ) influences the dissociation and regenerat...

In non-central heavy-ion collisions, the inhomogeneous expansion of the fireball creates an anisotropic flow in the transverse plane, indicating a quadrupole pattern of the longitudinal vorticity along the beam direction, which is responsible for the local polarization of Λ-hyperons. In this study, we explore the centrality and transverse momentum...

Relativistic heavy ion collisions provide the necessary conditions for forming a hot and dense thermalized partonic medium called Quark Gluon Plasma (QGP). This short-lived phase rapidly cools down hydrodynamically and, as a result of confinement, hadronizes near the critical temperature (Tc ' 156 MeV) to form a medium with hadronic degrees of free...

In the present study, we consider a viscous medium with non-zero vorticity, which is coupled with the spin of the particles and gives rise to spin polarization in the system. Here, the spin polarization tensor is obtained using a tensor decomposition method. We obtained the global spin polarization of Λ-hyperon using the vortical QGP evolution. Thi...

The O-O and p-O collisions are being studied to understand the origin of collectivity and test hydrodynamics in small systems. This research offers a key opportunity to explore the effects seen in high-multiplicity pp, p-Pb, and peripheral Pb-Pb collisions with similar charged-particle multiplicities. Analyzing the initial-state effects on the fina...

In ultra-relativistic collisions of nuclei at the Large Hadron Collider, the created QCD environment rapidly changes, leading to a non-adiabatic evolution of the quantum states involved. Considering this, we first examine the pre-equilibrium state of QCD matter and its effect on the initially produced charmonium using a temperature-independent Hami...

Relativistic heavy-ion collisions produce quark-gluon plasma (QGP), which is locally thermalized. Due to electrically charged particles (quarks), QGP exhibits interesting thermoelectric phenomena during its evolution, resulting in an electromagnetic (EM) field in the medium. In this study, for the first time, we estimate the induced electric field...

The hot and dense QCD matter, known as the Quark-Gluon Plasma (QGP), is explored through heavy-ion collision experiments at the LHC and RHIC. Jets and heavy flavors, produced from the initial hard scattering, are used as hard probes to study the properties of the QGP. Recent experimental observations on jet quenching and heavy-flavor suppression ha...

The second Hot QCD Matter 2024 conference at IIT Mandi focused on various ongoing topics in high-energy heavy-ion collisions, encompassing theoretical and experimental perspectives. This proceedings volume includes 19 contributions that collectively explore diverse aspects of the bulk properties of hot QCD matter. The topics encompass the dynamics...

Charmonia suppression has been considered as a smoking gun signature of quark-gluon plasma. However, the Large Hadron Collider has observed a lower degree of suppression as compared to the Relativistic Heavy Ion Collider energies, due to regeneration effects in heavy-ion collisions. Though proton collisions are considered to be the baseline measure...

The first measurement of the multiplicity dependence of intra-jet properties of leading charged-particle jets in proton–proton (pp) collisions is reported. The mean charged-particle multiplicity and jet fragmentation distributions are measured in minimum-bias and high-multiplicity pp collisions at center-of-mass energy $$\sqrt{s}$$ s = 13 TeV using...

Recently, with the upgradation of LHC, it is realized that study of heavy-flavored hadrons, namely [Formula: see text] and [Formula: see text] in hadronic collisions, could reveal the possibility of thermalization of charm quarks. With this motivation, we study the production dynamics of these hadrons using a pQCD-inspired Monte Carlo event generat...

A bstract The p T -differential production cross sections of non-prompt D ⁰ , D ⁺ , and $$ {\textrm{D}}_{\textrm{s}}^{+} $$ D s + mesons originating from beauty-hadron decays are measured in proton–proton collisions at a centre-of-mass energy $$ \sqrt{s} $$ s = 13 TeV. The measurements are performed at midrapidity, | y | < 0 . 5, with the data samp...

We developed a deep learning feed-forward network for estimating elliptic flow ($v_2$) coefficients in heavy-ion collisions from RHIC to LHC energies. The success of our model is mainly the estimation of $v_2$ from final state particle kinematic information and learning the centrality and the transverse momentum ($p_{\rm T}$) dependence of $v_2$ in...

Deuterons are atomic nuclei composed of a neutron and a proton held together by the strong interaction. Unbound ensembles composed of a deuteron and a third nucleon have been investigated in the past using scattering experiments, and they constitute a fundamental reference in nuclear physics to constrain nuclear interactions and the properties of n...

The present investigation reports the design and development of an advanced material with a high figure of merit (FoM) for beampipe applications in particle accelerators by bringing synergy between computational and experimental approaches. Machine learning algorithms have been used to predict the phase(s), low density, and high radiation length of...

We study the diffusion properties of an interacting hadron gas and evaluate the diffusion coefficient matrix for the baryon, strange, electric, and charm quantum numbers. For the first time, this study sheds light on the charm current and estimates the diffusion matrix coefficient for the charmed states by treating them as a part of the quasi-therm...

A bstract The angular correlations between charged Ξ baryons and associated identified hadrons (pions, kaons, protons, Λ baryons, and Ξ baryons) are measured in pp collisions at $$ \sqrt{s} $$ s = 13 TeV with the ALICE detector to give insight into the particle production mechanisms and balancing of quantum numbers on the microscopic level. In part...

In relativistic heavy-ion collisions, the formation of a deconfined and thermalized state of partons, known as quark-gluon plasma, leads to enhanced production of strange hadrons in contrast to proton-proton (pp) collisions, which are taken as baseline. This observation is known as strangeness enhancement in heavy-ion collisions and is considered o...

Quarkonium production in ultra-relativistic collisions plays a crucial role in probing the existence of hot QCD matter. This study explores quarkonia states dissociation and regeneration in the hot QCD medium while considering momentum anisotropy. The net quarkonia decay width arises from two essential processes: collisional damping and gluonic dis...

Studying the thermodynamics of the systems produced in ultra-relativistic heavy-ion collisions is crucial in understanding the QCD phase diagram. Recently, a new avenue has opened regarding the implications of large initial angular momentum and subsequent vorticity in the medium evolution in high-energy collisions. This adds a new type of chemical...

A study of strange hadron production associated with hard scattering processes and with the underlying event is conducted to investigate the origin of the enhanced production of strange hadrons in small collision systems characterised by large charged-particle multiplicities. For this purpose, the production of the single-strange meson \( {\textrm{...

A bstract The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ s NN = 5 . 02 TeV down to transverse momentum ( p T ) of 0.5 GeV/ c and 2 GeV/ c , respectively, with ALICE. The results obtained in p-Pb collision...

This Letter presents the most precise measurement to date of the matter-antimatter imbalance at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair s NN = 5.02 TeV . Using the Statistical Hadronization framework, it is possible to obtain the value of the electric charge and baryon chemical potentials, μ Q = − 0.18 ± 0.90 MeV...

The ALICE experiment was proposed in 1993, to study strongly-interacting matter at extreme energy densities and temperatures. This proposal entailed a comprehensive investigation of nuclear collisions at the LHC. Its physics programme initially focused on the determination of the properties of the quark–gluon plasma (QGP), a deconfined state of qua...

In proton-proton and heavy-ion collisions, the study of charm hadrons plays a pivotal role in understanding the QCD medium and provides an undisputed testing ground for the theory of strong interaction, as they are mostly produced in the early stages of collisions via hard partonic interactions. The lightest open charm, D 0 meson ( c u ¯ ), can ori...

The inclusive production of the charm-strange baryon Ω c 0 is measured for the first time via its semileptonic decay into Ω − e + ν e at midrapidity ( | y | < 0.8 ) in proton-proton (pp) collisions at the center-of-mass energy s = 13 TeV with the ALICE detector at the LHC. The transverse momentum ( p T ) differential cross section multiplied by the...

The two-particle momentum correlation functions between charm mesons ( D * ± and D ± ) and charged light-flavor mesons ( π ± and K ± ) in all charge combinations are measured for the first time by the ALICE Collaboration in high-multiplicity proton–proton collisions at a center-of-mass energy of s = 13 TeV . For DK and D * K pairs, the experimental...

Nuclei having $4n$ number of nucleons are theorized to possess clusters of $\alpha$ particles ($^4$He nucleus). The Oxygen nucleus ($^{16}$O) is a doubly magic nucleus, where the presence of an $\alpha$-clustered nuclear structure grants additional nuclear stability. In this study, we exploit the anisotropic flow coefficients to discern the effects...

Collectivity is an essential feature of the strongly interacting matter formed in the deconfined phase of quarks and gluons in the nucleus-nucleus (A-A) collisions at relativistic energies. Extensive experimental evidence from heavy-ion collisions at RHIC and LHC energies has conclusively demonstrated the collective behavior. Moreover, the compelli...

The existence of different phases of matter produced in relativistic heavy-ion collisions requires a hadronic description, creating much interest in the hadronic phase. We explore the possibility of thermalization and applicability of hydrodynamics in a hadron gas medium using the Knudsen number (Kn). Kn << 1 implies a system with a large number of...

Short-lived hadronic resonances with widely varying lifetimes provide an excellent tool to study the hadronic phase produced in relativistic heavy ion collisions. The dynamics of these particles, especially the K∗(892)0 meson, and thus varying yields has been used extensively to study the hadronic phase lifetime. In this work we employ an alternati...

The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high p T ) charged hadron, in p p and central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collision s NN = 5.02 TeV. The large uncorrelated background in central Pb-Pb collisions is co...

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high p T ) hadron trigger in proton-proton and central Pb-Pb collisions at s NN = 5.02 TeV . A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb colli...

Long-range multi-particle correlations in heavy-ion collisions have shown conclusive evidence of the hydrodynamic behavior of strongly interacting matter, and are associated with the final-state azimuthal momentum anisotropy. In small collision systems, azimuthal anisotropy can be influenced by the hadronization mechanism and residual jet-like corr...

Measurements of the p T -dependent flow vector fluctuations in Pb–Pb collisions at s NN = 5.02 TeV using azimuthal correlations with the ALICE experiment at the Large Hadron Collider are presented. A four-particle correlation approach [ALICE Collaboration, ] is used to quantify the effects of flow angle and magnitude fluctuations separately. This p...

High-energy cosmic ray experiments consistently report an excess of secondary cosmic ray muons at ground level, defying predictions from prevalent high-energy interaction models: a phenomenon known as the “Muon Puzzle”. The universal enhancement of strangeness and baryon production in p-p, p-Pb, and Pb-Pb collisions seen by the ALICE collaboration...

The strongly interacting quarks and gluons plasma (QGP) phase is a must to exhibit the collective behavior. Experimental observations from heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) revealed such collective phenomena. Additionally, intriguing features like strangeness enhancement further s...

K + K − pairs may be produced in photonuclear collisions, either from the decays of photoproduced ϕ ( 1020 ) mesons or directly as nonresonant K + K − pairs. Measurements of K + K − photoproduction probe the couplings between the ϕ ( 1020 ) and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above t...

A bstract The production yields of the Σ(1385) ± and Ξ(1530) ⁰ resonances are measured in pp collisions at $$ \sqrt{s} $$ s = 13 TeV with ALICE. The measurements are performed as a function of the charged-particle multiplicity ⟨d N ch / d η ⟩, which is related to the energy density produced in the collision. The results include transverse momentum...

A Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies,...

Relativistic heavy-ion collisions produce quark-gluon plasma (QGP), which is locally thermalized. QGP with higher thermal conductivity advances towards global thermalization. Being made of electrically charged particles (quarks), QGP exhibits interesting thermoelectric phenomena during its evolution, resulting in the induction of an electric field...

A bstract Results on the transverse spherocity dependence of light-flavor particle production ( π , K, p, ϕ , K *0 , $$ {\textrm{K}}_{\textrm{S}}^0 $$ K S 0 , Λ, Ξ) at midrapidity in high-multiplicity pp collisions at $$ \sqrt{s} $$ s = 13 TeV were obtained with the ALICE apparatus. The transverse spherocity estimator $$ \left({S}_{\textrm{O}}^{p_{...

A bstract Measurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV and the corresponding nuclear modification factor $$ {R}_{\textrm{pPb}}^{\textrm{ch}\ \textrm{jet}} $$ R pPb ch jet are presented, using data collected wi...

A bstract The ALICE Collaboration reports a search for jet quenching effects in high-multiplicity (HM) proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV, using the semi-inclusive azimuthal-difference distribution ∆ φ of charged-particle jets recoiling from a high transverse momentum (high- p T , trig ) trigger hadron. Jet quenching may broaden...

This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s = 13 TeV . Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4 < | Δ η | < 1.8 and a transverse...

The global and local polarization measurements of Λ (Λ) hyperons by STAR and ALICE Collaborations open up an immense interest in investigating the polarization dynamics in heavy-ion collisions. Recent studies suggest the transverse component of the vorticity field is responsible for the global spin polarization, while the longitudinal component of...

The first measurement of the cross section for incoherent photonuclear production of J / ψ vector mesons as a function of the Mandelstam | t | variable is presented. The measurement was carried out with the ALICE detector at midrapidity, | y | < 0.8 , using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of s NN...

Strong transient magnetic fields are generated in noncentral relativistic heavy-ion collisions. These fields induce anisotropy within the strongly interacting medium that, in principle, can affect the thermodynamic properties of the medium. We use the Polyakov loop extended Nambu Jona-Lasinio model to study the quark matter subjected to an external...

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c + baryons, z...

The production of K * ( 892 ) ± meson resonance is measured at midrapidity ( | y | < 0.5 ) in Pb − Pb collisions at s N N = 5.02 TeV using the ALICE detector at the CERN Large Hadron Collider. The resonance is reconstructed via its hadronic decay channel K * ( 892 ) ± → K S 0 π ± . The transverse momentum distributions are obtained for various cent...

The production mechanisms of charmonium states in both hadronic and heavy-ion collisions hold great significance for investigating the hot and dense QCD matter. Studying charmonium polarization in ultrarelativistic collisions can also provide insights into the underlying production mechanisms. With this motivation, we explore the J/ψ and ψ(2S) pola...

A bstract Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at $$ \sqrt{s} $$ s = 13 TeV and p–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV. The correlation functions are measured as a function of relative azimuthal angle ∆ φ and pseudorapidity sep...

The charged-particle transverse momentum spectra (\(p_\textrm{T}\)-spectra) measured by the ALICE collaboration for pp collisions at \(\sqrt{s} =\) 7 and 13 TeV have been studied using a thermodynamically consistent form of Tsallis non-extensive statistics. The Tsallis distribution function is fitted to the \(p_{\textrm{T}}\)-spectra and the result...

The recent observation of global polarization of Λ (Λ) hyperons and spin alignment of ϕ and K * 0 vector mesons create remarkable interest in investigating the particle polarization in the relativistic fluid produced in heavy-ion collisions at GeV/TeV energies. Among other sources of polarization, the Debye mass of a medium plays a crucial role in...

Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the CERN Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle...