Conveners
WG5-Heavy Ions and QCD: D1-S1 - Parallel - 3
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
- Kumar Meduri Chakravartula (IIT Guwahati)
- Natasha Sharma (Panjab University (IN))
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
WG5-Heavy Ions and QCD: D1-S2 - Parallel - 3
- Kumar Meduri Chakravartula (IIT Guwahati)
- Natasha Sharma (Panjab University (IN))
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
WG5-Heavy Ions and QCD: D2-S1 - Parallel - 3
- Natasha Sharma (Panjab University (IN))
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
- Kumar Meduri Chakravartula (IIT Guwahati)
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
WG5-Heavy Ions and QCD: D2-S4 - Parallel - 4
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
- Kumar Meduri Chakravartula (IIT Guwahati)
- Natasha Sharma (Panjab University (IN))
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
WG5-Heavy Ions and QCD: D3-S5 - Parallel - 3
- Natasha Sharma (Panjab University (IN))
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
- Kumar Meduri Chakravartula (IIT Guwahati)
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
WG5-Heavy Ions and QCD: D3-S6 - Parallel - 4
- Natasha Sharma (Panjab University (IN))
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
- Kumar Meduri Chakravartula (IIT Guwahati)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
WG5-Heavy Ions and QCD: D4-S7 - Parallel - 4
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
- Natasha Sharma (Panjab University (IN))
- Kumar Meduri Chakravartula (IIT Guwahati)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
WG5-Heavy Ions and QCD: D4-S8 - Parallel - 4
- Natasha Sharma (Panjab University (IN))
- Sidharth Kumar Prasad (Department of Physics, Bose Institute, Kolkata 700091, India)
- Kumar Meduri Chakravartula (IIT Guwahati)
- Bedangadas Mohanty (National Institute of Science Education and Research (NISER) (IN))
- Partha Pratim Bhaduri (Variable Energy Cyclotron Centre)
In a hard interaction at the LHC, the partons due to the QCD confinement property hadronize to form jets. The identification of jets and flavor tagging of jets is very important to many physics analyses for precise measurements of the standard model and new resonance searches. The performance studies on identifying the quark and gluon jets using different discriminators and their tagging...
Measurements of heavy-flavour tagged jets, and heavy-flavour particle azimuthal correlation with charged particles allow for comparisons of the heavy quarks (charm and beauty) production, propagation, and hadronization across different collision systems. Comparison of measurements performed in pp with p--Pb collisions can help studying the possible modification of the heavy-quark production...
Jet energy loss is investigated using the nuclear modification factor (R$_{AA}$) observable in heavy ion collisions at RHIC and LHC energies. We employ Jet Energy-loss Tomography with a Statistically and Computationally Advanced Program Envelope (JETSCAPE) framework to depict jet quenching phenomena, to analyze the multi-stage jet evolution in quark-gluon plasma (QGP) medium. In this work,...
Recent results in high-multiplicity pp collisions show features similar to those that are associated with the formation of a quark-gluon plasma in heavy-ion collisions [1]. Investigating the modification of the intra-jet properties as a function of event multiplicity in pp collisions can provide deeper insight into the nature of these effects. We will present the recent measurements of...
Heavy quarks (charm and beauty) have masses much larger than the characteristic energy scale of QCD interaction. Due to this they are typically produced in hard scattering processes with large $\{Q}^2$ and thus offer a unique perspective to study the transition from quark to hadrons in all collision systems. Recent production measurements of charm baryons and mesons in small system at...
The study of prompt direct photons, from Compton scattering and annihilation hard processes in hadronic collisions, can test perturbative quantum chromodynamics theory predictions. In pp collisions, they can be used to constrain parton distribution functions as they come directly from the parton-parton hard scatterings. The measurement of direct photon production is complicated due to the...
Heavy quarks (HQs) are considered as effective probes to study the evolution of the quark-gluon plasma (QGP). We study the dynamics of HQs in a hot QCD medium with a time-correlated noise, ฮท. We have introduced the effect of memory through ฮท and the dissipative force in the Generalized Langevin equation (GLV). We assume that the time correlations of the colored noise decay exponentially with...
There is serious disagreement between the predictions of Non-Relativistic Quantum Chromodynamics (NRQCD) and the data on $J/\psi$ polarisation which has persisted for almost a quarter of a century. We find that if we account for the effect of perturbative soft gluons on the intermediate charm-anticharm octet states in NRQCD then the polarisation problem can be resolved. In addition, this...
The production of charmonium and its suppression in heavy-ion collisions is an ideal probe to explore the Quark-Gluon Plasma (QGP) in the laboratory. Suppression can also take place in hadron-nucleus collisions due to cold nuclear matter (CNM). The hadron-nucleus collisions are therefore important as they help disentangling the effects of the QGP from those due to CNM. The Charmonium...
We demonstrate high prediction accuracy of three important properties that determine the initial geometry of the heavy-ion collision (HIC) experiments by using supervised machine learning (ML) methods. These properties are the impact parameter, the eccentricity, and the participant eccentricity. Although ML techniques have been used previously to determine the impact parameter of these...
In this talk, I will discuss the technical challenges in analytic computations of multi-loop integrals that appear in higher-order perturbative computations. I will explain the techniques for computing integrals with massive internal propagators needed for two-loop QCD corrections for Higgs decays and NNLO QCD corrections for ttj production. The inclusion of massive internal propagators often...
The proton spin crisis is a long-term issue in spin physics, implying that the quark only carries a fraction of the proton's spin.
To compensate for the proton's spin, the spin sum rules are given.
These rules state that in a longitudinally polarized proton, the spin carried by the quarks and gluons, as well as their orbital angular momentum (OAM), must add to the proton spin.
This...
Singular factors originating from the QCD factorisation of scattering amplitudes in soft and collinear limits play a prominent role in both organising and computing high-order perturbative contributions to hard-scattering cross sections. In this talk, I will report on recent work with eprint number 2208.05840. We start from the factorisation structure of scattering amplitudes in the collinear...
One of the classic ways of studying QCD events in high energy experiments is to measure the Event Shape variables e.g., Thrust, Jet Broadening, Angularity etc. which are observables designed to characterize several properties including the geometric shape of hadron distribution in the event. In this talk, we will discuss a more general global event shape "angularity" for deep inelastic...
In this talk, I discuss the calculation of all helicity amplitudes for four-parton scattering in three-loop massless QCD. Our results allow us, for the first time, to verify completely the structure of quadrupole IR divergences at this perturbative order in QCD. From the high-energy limit of the amplitudes, we have extracted the three-loop gluon Regge trajectory in full QCD. Our findings...
The ALICE experiment at the LHC is designed to study the hot and dense medium produced in ultrarelativistic heavy-ion collisions. Due to their short lifetimes, resonances are useful tools to understand the mechanism of particle production and properties of the hadronic phase created after these collisions. The yield of resonances might be modified with respect to expectations due to in-medium...
Hadronic resonances are effective tools for studying the hadronic phase in ultrarelativistic heavy-ion collisions.ย In fact, their lifetime is comparable to that of the hadronic phase, and resonances are sensitive to effects such as rescattering and regeneration processes, which might affect the resonance yields and shape of the transverse momentum spectra. These processes can be studied...
The short-lived resonances, like $K^{*0}$, are a good candidate to probe the hadronic phase of the matter formed in heavy-ion collisions. Due to its short lifetime, the decay daughters may interact with the hadronic medium, resulting in a change in the properties of the resonances. The decay daughters may undergo various in-medium effects like rescattering and re-generation. Hence $K^{*0}/K$ ...
Ultraperipheral lead-lead collisions produce very large photon fluxes that fundamental quantum-mechanical processes can be observed and well studied. The first measurement of $\tau$ lepton pair in ultraperipheral PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV with data collected by CMS during the LHC Run 2 will be presented. The study paves the way for the determination of the...
Global observables such as the pseudorapidity distributions of particle multiplicities in the final state are crucial to shed light into the physics processes involved in hadronic collisions. In proton-lead (p-Pb) collisions at LHC energies, such measurements provide an important baseline to understand lead-lead (Pb-Pb) results by disentangling hot nuclear matter effects from cold nuclear...
There have been several signatures of quark-gluon plasma (QGP) seen in the TeV proton+proton collisions at the Large Hadron Collider (LHC) energies, some of those include long-range ridge-like correlations, strangeness enhancement, comparable freeze-out temperature with a deconfinement transition temperature, etc.. Although so far it is inconclusive to conclude on the formation of QGP in TeV...
The proliferating list of experimentally discovered heavy quark exotic hadrons calls for urgent first principles theoretical investigations. We present a status update of our ongoing calculation of tetra-quark states composed of a bottom and a charm quark in isospin I=0, axial-vector ($J^P=1^+$) channel using first principles Lattice Quantum Chromodynamics.
These calculations are performed...
Effective field theories (EFTs) provide us a powerful way of organising low-energy physics of interest in quantum field theories. The Physics of QCD at very low temperature and at very high temperature are well described by; respectively, theory of pions, and an effective weak coupling expansion. These EFTs usually depend on hierarchy of scales, and usually become ineffective when temperature...
We present here for the first time the impact-parameter dependent saturated dipole model (bSat or IP-Sat) with a fit [1] to the leading neutron structure function HERA data in one pion exchange approximation. We estimate the magnitude of gluon saturation effects by performing a fit to the same data with the linearised version of the considered dipole amplitude and comparing both models. Our...
Event-by-event fluctuations of the mean transverse momentum, $\langle p_{\rm T}\rangle$, of charged particles produced in Pb-Pb and Xe-Xe collisions at $\sqrt{s_\rm{NN}}$ = 5.02 TeV and $\sqrt{s_\rm{NN}}$ =5.44 TeV, respectively, are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations are observed in both collision systems...
The event-by-event fluctuations of conserved quantities, such as, baryon number, strangeness and electric charge in ultrarelativistic heavy-ion collisions are related to thermodynamic properties of the produced hot and dense system and may reveal the properties of the quark--gluon plasma and the QCD phase diagram. In the present work, the net-charge fluctuations are studied in terms of the...
Two-particle charge-dependent correlations (balance functions) are sen- sitive to the production and transport of conserved quantum numbers in the medium created in hadronic collisions. In this contribution, recent ALICE measurements of the balance functions of charge, strangeness, and baryon numbers are presented. Balance functions for all combinations of identified charged-hadron (ฯ, K, p)...
Lattice QCD predicts an ordering of the ratios of baryon number fluctuations in the vicinity of critical point in the QCD phase diagram i.e, $\frac{\chi_6}{\chi_2}<\frac{\chi_5}{\chi_1}<\frac{\chi_4}{\chi_2}<\frac{\chi_3}{\chi_1}$ where $\chi_n$ is the nth order cumulant of baryon number fluctuation. Taking the analog of baryon density as order parameter in the spin model, these inequalities...
The Taylor expansion of thermodynamic observables at a finite baryon chemical potential $\mu_B$ is a well-known approach to circumvent the fermion sign problem. The reliability of a Taylor estimate is determined by the radius of convergence, a reasonable estimate of which requires sufficiently higher order calculations in $\mu_B$. But, owing to the associated difficulty and limitations of...
The hadron resonance gas (HRG) model which considers a grand canonical ensemble of all the experimentally established hadrons and resonance states, is very successful in reproducing the LQCD results of the hadronic phase of the strongly interacting matter. Various extensions of the HRG model have been made to improve its agreement with LQCD results. One such extension is the implementation of...
Thermal photons from the QGP provide important information about the interaction among the plasma constituents. The photon production rate from a thermally equilibrated plasma is proportional to the transverse spectral function $\rho_T$(๐0=|๐โ |,๐โ ). Photon production rates can also be calculated from the difference between $\rho_T$(transverse) and $\rho_L$(longitudinal) correlator as...
In heavy-ion collisions, a strong magnetic field ($\sim$ 10$^{15}$ T) is expected to be created, which together with the presence of a non-zero vector and axial currents, gives rise to a collective excitation in the quark--gluon plasma (QGP) called the Chiral Magnetic Wave (CMW). The experimental signature of the CMW is charge-dependent elliptic flow, $v_{2}$. In particular, the normalized...
We study the effect on thermal vorticity near the QCD critical point. To evaluate thermal vorticity, we solve the equations for the relativistic causal hydrodynamics in (3+1) dimensions. The effects of the critical point is incorporated through the equation of state and the scaling behaviour of the transport coefficients. We observed a significant suppression in thermal vorticity at late times...
Experiments conducted in the last decade to search for the Chiral Magnetic Effect (CME) in heavy-ion collisions have been inconclusive. Isobar program at RHIC was conducted to address this problem. Also, in order to study the CME, a new approach known as the Sliding Dumbbell Method (SDM) [1] has been developed. This method searches for the back-to-back charge separation on an...
Loosely bound light nuclei are produced in abundance in heavy-ion collisions. There are two main possible models to explain their production mechanism - the thermal model and the coalescence model. Thermal model suggests that the light nuclei are produced from a thermal source, where they are in equilibrium with other species present in the fireball. However, due to the small binding energies,...
The fireball of quarks and gluons formed in relativistic heavy ion collisions converts to hadrons as it cools below the chiral crossover temperature $(T_{CO})$. The hadrons so formed may further interact till a point where the densities are low enough to make the reaction rates negligible. After this the yields of individual species do not change significantly and get essentially fixed. This...
We study the thermoelectric response of a thermal medium of deconfined quarks and gluons in the framework of relativistic kinetic theory. The response of the medium is quantified by the Seebeck and Nernst coefficients which relate the mutually longitudinal and transverse components, respectively, of the induced electric field and the temperature gradient. To obtain the above coefficients, we...
Photons provide snapshots of the evolution of relativistic heavy-ion collisions as they are emitted at all stages and do not interact with the medium strongly. With access to the versatility of RHIC, measurements of low momentum direct photons are made possible across different system size and beam energies. An excess of direct photons, above prompt photon production from hard scattering...
Elastic light-by-light scattering, $\gamma\gamma\rightarrow\gamma\gamma$, is a pure quantum mechanical process, also proposed as a sensitive channel to study physics beyond the standard model. We present the first combination of $\gamma\gamma\rightarrow\gamma\gamma$ cross-section measurement at the LHC, using lead-lead data recorded by the ATLAS and CMS collaborations at 5.02 TeV with the aim...
