Previous ALICE studies have shown a stronger than linear relative increase of the inclusive J/ψ production at mid-rapidity as a function of the mid-rapidity charged-particle multiplicity in proton-proton collisions. Studies on Monte Carlo simulations with PYTHIA 8 attributed this behavior to
autocorrelation effects. In this regard, interesting results were obtained studying the correlation...
In relativistic heavy-ion collisions, heavy quarks (charm and beauty) are predominantly produced in the early stage of the collisions via hard partonic scattering processes. Therefore, they experience the full evolution of hot and dense QCD matter in which quarks and gluons are de-confined (Quark-Gluon Plasma, QGP) created by such collisions, and can be an effective probe to study the QGP...
The study of anisotropic flow provides strong constrains to the evolution of the medium produced in heavy ion collisions and its event-by-event geometry fluctuations. These observables have long been related to collective behaviour in the formed medium. Recent results both at RHIC and LHC provide strong evidence for the formation of such medium in smaller systems.
RHIC has had a broad...
The high collision energies available at the LHC allow for an abundant production of heavy quarks (charm and beauty), which are sensitive probes for investigating the properties of the Quark-Gluon Plasma (QGP) formed in high-energy heavy-ion collisions. Due to their large masses, they are produced in initial hard parton scattering processes on a timescale shorter than the QGP formation time...
The NA61/SHINE hadron physics program focuses on a search for the critical point and on studies of the properties of the onset of deconfinement in strongly interacting matter. For this purpose the phase diagram is scanned by changing the collision energy (from 13A to 150/158A GeV/c) and the size of the colliding system (from p+p to Pb+Pb).
The main topic of this talk are preliminary results...
Recent experimental and theoretical obsevations suggest that production of (multi-)strange hadrons and charged hadrons in (non-)deformed nuclei is a complex physical process. The properties of charged hadrons produced in deformed nucleus collisions at RHIC and LHC energies contradict many of the theoretical models result including two-component Monte Carlo Glauber model. Unlike light hadrons,...
We report the first measurement of the Ξ(1820) baryon at LHC energies by reconstructing its decay to Λ-Κ in pp collisions at 13 TeV. Recent lattice calculations on parity doubling indicate that the masses of negative-parity particles, such as Ξ(1820), may decrease at the critical temperature, while the masses of positive-parity partners, i.e. the Ξ(1530), do not. Furthermore, the lifetime of...
One of the important goals of heavy-ion collision experiments is to test the predictions of Quantum Chromodynamics(QCD). One such QCD prediction is the formation of Quark-Gluon Plasma(QGP) in the heavy-ion collision experiments. Quarkonia suppression has been suggested as a sign of formation of QGP in heavy ion collision, where it could exist as a transient state. We have developed a model to...
It is understood that multiplicity fluctuations serve as one of the important observables for the study of the critical endpoint in the beam energy scan program of RHIC.
As a matter of fact, the problem is rather subtle, and many different factors may potentially affect the observable in question.
In this work, we take into consideration the thermal fluctuations, resonance decay, as well...
The Multi-Purpose Detector (MPD) is being constructed to study the properties of extremely dense nuclear matter formed in relativistic nucleus-nucleus collisions at NICA energies. The yields of strange and charmed particles are the important observables sensitive to critical phenomena in phase transitions of the QGP-matter at high net-baryon density. Highly efficient registration of such...
Correlated dielectron pairs are a very promising probe to study the quark-gluon plasma, a deconfined state of quarks and gluons predicted by lattice quantum chromodynamics calculations in ultra-relativistic heavy-ion collisions. Electrons reach the detector without significant final state interactions. In addition, the low-mass dielectron spectrum comes from various sources, i.e. Dalitz and...
We present an object-oriented software framework for performing the anisotropic flow analysis in collisions of ions and hadrons. The framework operates on flow Q-vectors and provides an abstraction layer for the analysis of two and multi-particle correlation functions. Its modular design and flexible interface allows to use it as an external software package, which fits the scope of any...
We consider causal higher order theories of relativistic viscous hydrodynamics in the case of one-dimensional boost-invariant expansion and study the associated dynamical attractor. We obtain the evolution equations for inverse Reynolds number as a function of inverse Knudsen number. The solutions of these equations exhibit attractor behavior which we analyze in the context of Lyapunov...
The NA61/SHINE experiment at the CERN SPS has recently extended its program for the energy scan with Pb ions. In the past, the NA49 experiment, which preceded the NA61/SHINE, has also recorded data for Pb–Pb collisions at different energies. Together, the two experiments cover wide range of collision energies in the beam momentum range of 13–150A GeV/c provided by CERN SPS. Analysis of the new...
Recently anomaly related transports have attracted lot of interests in various fields. Ranged from low energy physics and in condensed matter up to high energy physics and in heavy ion collisions, physicists are interested to study the effects of microscopic anomaly over the macroscopic scales. Historically this stream is initiated by the work of Vilenkin in 1979 [ A.~Vilenkin, Phys. Rev. D ...
We use several methods to study the case of chiral anomaly with a non-relativistic dispersion relation $H=\frac{p^2}{2m}+\lambda\sigma\cdot p$, which might be useful in special condensed matter state. where $H$ means halmitonian.$\lambda$ is just a constant coeffecient.
we will show the results with different explanations in each methods. For example, the anomaly disappears for the lack of...
Various flow observables, defined based on the Fourier decomposition, have provided valuable information on the initial state fluctuations, final state correlations and the QGP properties. In spite of the success of the flow measurements and the hydrodynamic descriptions, one essential question is why the Fourier expansion is a natural way to analyze the flow data. In this talk, I will address...
Flow correlations and fluctuations are sensitive probes to the initial geometry and the quark-gluon plasma (QGP) in relativistic heavy ion collisions. Model comparisons are essential to decipher the properties of the QGP. In this talk, we study the correlations between flow harmonics $v_2$, $v_3$, and $v_4$ over a wide centrality range with two-particle correlations in PbPb collisions at...
The hadronic interaction cross section for (multi)strange hadrons are expected to be small. Hence, the study of azimuthal anisotropy of (multi)strange hadrons allows one to access the collective properties of early stages in heavy-ion collisions. The STAR experiment recently recorded high statistics data for Au+Au collisions at a new centre-of-mass energies ($\sqrt{s_{NN}}$) of 54.4 GeV...
Two-particle angular correlations are used to investigate properties of the Quark-Gluon Plasma (QGP) formed in high-energy heavy-ion collisions. They are sensitive to different effects of the evolution of the collision, such as collective effects, initial conditions and jet properties.
In small systems (such as pp or p--A collisions), an unexpected double-ridge structure has been observed...
The measurement of modification of jet yields in heavy-ion collisions provides a powerful method to probe the dynamics of the hot, dense medium formed in these collisions at the LHC. Jet quenching in heavy-ion collisions is expected to depend on the flavor of the fragmenting parton. For light partons, energy loss via gluon bremsstrahlung is expected to dominate, while in the case of...
The Chiral Magnetic Effect (CME) manifests itself via a separation of electric charge along the direction of the magnetic field, produced by spectator protons in heavy-ion collisions. The experimental searches for the CME, based on the charge-dependent angular correlations [1] have, however, remained inconclusive till date, because the observed features of charge separation in data are also...
We present new results for fluctuations of the baryon number for QCD with
Nf=2+1 quark flavours at non-zero temperature and chemical potential [1].
These are extracted from a framework based on a combination of lattice QCD
and Dyson-Schwinger equations. In previous works ([2], see [3] for a review)
we found a critical end point in the region ($T^c,\mu_B^c$)=(120,500) MeV.
We discuss...
sPHENIX is a planned upgrade at RHIC designed to quantify the properties of quark-gluon plasma created in relativistic heavy ions collisions with a particular focuses on the measurements of jets and upsilon states. A crucial component to the sPHENIX detector design for jet measurements is the hadronic calorimeter (HCal) which is located outside of the solenoid magnet and composed of...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will quantify the properties of quark-gluon plasma created in relativistic heavy ions collisions with a focus on the measurements of jets and Upsilon states. A crucial component to the sPHENIX detector design for jet measurements is the hadronic calorimeter (HCal) which is located outside of the solenoid magnet and composed...
Femtoscopic measurements can be leveraged to gain insight into the expansion dynamics of the hot and dense medium created in heavy-ion collisions. This poster presentation will report and discuss excitation functions for shape-selected two-pion HBT radii ($R_{out}$, $R_{side}$ and $R_{long}$) measured for a a broad range of collision centrality and average pair transverse momentum ($k_{T}$)...
Recent ALICE results have demonstrated that femtoscopic measurements in pp and p-Pb collisions provide an unprecedented opportunity to study the short range part of the strong interaction.
Femtoscopy is a technique to extract information on the emission source and interaction potential from correlations between particles with low relative momentum. In this talk we will use femtoscopy to...
The study of the charm and bottom interacting with the QGP strongly relies on the precise measurement of their yields in p+p collisions, since the theoretical calculations of the yields have large uncertainties. The PHENIX collaboration has measured the semi-leptonic decay yields of charm and bottom hadrons and the non-prompt $J/\psi$ yield from B meson decays in 200 GeV $p$+$p$ collisions,...
We compute for the first time the suppression of bottomonia in a strongly coupled QGP and compare the results to those from a weakly coupled QGP and to data. Using imaginary time techniques we numerically determine the real and imaginary parts of the binding energy of $\Upsilon$(1S) in (complex) potentials derived from AdS/CFT and from pQCD. We confirm the strong coupling binding energies by...
Bottomonia are produced mostly in the initial stage of a heavy ion collision. Once created, any subsequent interaction with the medium can as a first approximation be dealt with as leading to dissociation. In that picture, the bottomonia surviving until the final state are those that escaped any interaction with the medium.
We compute the anisotropic flow of bottomonia arising from their...
Bottomonium, a bound state of a bottom quark and its antiquark, is an excellent probe of the hot and dense medium created in heavy-ion collisions at LHC. The ATLAS collaboration collected the large datasets of $pp$ and Pb+Pb collisions in 2017 and 2018 corresponding to integrated luminosities of 242 pb$^{-1}$ and 1.39 nb$^{-1}$ respectively, at a centre-of-mass energy per nucleon pair of 5.02...
Ideal Hadron Resonance Gas (HRG) model is a well-known tool to describe hadron multiplicities in relativistic nuclear collisions and for modelling hadronic equation of state. The model relies on the assumption that all hadronic resonances are free particles, which is valid, given that their decay widths are negligible. However, when the temperature is close to the crossover region, the model...
In the soft and collinear limit, the choice of evolution scale in a parton shower algorithm is ambiguous and several options have been implemented in existing Monte Carlo event generators for proton-proton collisions. However, the resulting space-time evolution could result in subtle differences depending on the particular choice. In this work we quantify measurable consequences of the choice...
We examine the relativistic perfect fluid limit, defined as the fastest possible local equilibration,
in a medium with polarizeability, defined as a non-zero local equilibrium partition of angular
momentum into spin and vorticity. We show that the Lagrangian approach is best suited to
analyzing this situation, as it can be used to efficiently avoid issues such as the breakdown...
sPHENIX is an ongoing upgrade to the PHENIX detector which is planned to explore the quark-gluon plasma formed in heavy ion collisions through the measurements of jets and Upsilons at RHIC in the 2020’s. The experiment will feature a charged particle tracking system along with electromagnetic and hadronic calorimeters and also a 1.4 Tesla superconducting solenoid magnet. A TPC with a GEM-based...
Bottom and charm production is a powerful tool to investigate the properties of
quark gluon plasma created in high energy heavy ion collisions. Heavy flavor production is calculable by perturbative QCD because of their large mass.
Once produced, they traverse the QGP and suffer the hot medium effects such as
energy losses. The collisional and radiative mechanisms play an important role of...
Event-by-event fluctuation of conserved quantities such as net baryon, net strangeness or net charge is considered to be a powerful tool to find the critical point (CP) on the Quantum Chromodynamics (QCD) phase diagram. To map out the QCD phase diagram, the Beam Energy Scan I (BES-I) program has been carried out at RHIC and non-monotonic behavior of the 4th-order net-proton cumulants was found...
The Compressed Baryonic Matter (CBM) experiment at the FAIR facility aims to explore the QCD phase diagram at very high baryon densities, where a first order phase transition from hadronic to partonic matter as well as a chiral phase transition is expected to occur.
The Silicon Tracking System is the central detector for momentum measurement and charged-particle identification. It is designed...
The Compressed Baryonic Matter (CBM) experiment is a fixed-target heavy-ion physics experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. The CBM physics program aims at exploring the QCD phase diagram at very high baryon densities. For high-statistics measurements of rare probes, CBM is designed to cope with very high interaction rates up to 10 MHz. To...
One of the novel anomalous chiral effects, the chiral magnetic wave (CMW), has been experimentally searched by using the charge-dependent anisotropic flow in recent years. The observed linear dependence between the charge asymmetry and the flow of the positively and negatively charged hadrons, however, still remains inconclusive owing to the existence of background effects such as local charge...
In this poster, we will present measurements of event-by-event charge separation in Au+Au collisions at $\sqrt{{\it{s}}_{NN}} = 200$ GeV using Sliding Dumbbell Method (SDM). The charge dependent three-particle correlator ($\gamma = \langle cos(\phi_{a} + \phi_{b} - 2.{\Psi}_{RP}) \rangle$) which is the observable for Chiral Magnetic Effect (CME) [1] is investigated for each centrality...
Resonances are useful tools to study the properties of the hadronic medium produced in high energy heavy-ion collisions, due to their short lifetime. In particular, the baryonic resonance $\Lambda(1520)$ is important because of its lifetime ($\tau \sim$ 12.6 fm/$\it c$), which lies in between the lifetimes of $ K^*$ and $\phi$ resonances.
Its study will indicate the dominance of...
Hadronic resonances have been shown to be good probes to investigate the late-stage evolution of ultra-relativistic heavy-ion collisions. Their lifetimes are comparable with the time scale of the fireball generated in these collisions. Therefore they are sensitive to the competing re-scattering and regeneration effects occurring in the hadronic phase, which modify particle momentum...
Strangeness enhancement has been observed for several multi-strange hadrons in proton-proton (pp) collisions with increasing charged-particle multiplicity and is in remarkable agreement with measurements in p-Pb collisions. The yields of resonances with short lifetimes are sensitive to regeneration and re-scattering processes in the hadronic phase between chemical and kinetic freeze out. It is...
The ALICE experiment at the LHC is designed to investigate the properties of the Quark-Gluon Plasma by studying high-energy pp, p--Pb, Pb--Pb and Xe--Xe collisions. Medium effects like parton energy loss can be examined by measuring the production of charged particles and their nuclear modification at high transverse momentum ($\textit{p}_{\text{T}}$).
In this poster, we report on...
Heavy quarks (charm and beauty) are believed to be produced predominately in hard scattering processes at early stage of the collisions before the QGP production so they can pass through the hot-dense medium completely, and their production yields can be calculated by perturbative-QCD, which makes them ideal probes for QGP. According to the theoretical prediction, energy loss of heavy quarks...
Heavy quarks (charm and beauty) are an effective tool to study the properties of the Quark-Gluon Plasma (QGP) formed in heavy-ion collisions at the LHC. Due to their large mass, they are produced during the early stages of the collisions in hard-scattering processes, on a time interval shorter than the QGP formation time. Thus, they experience the whole evolution of the system. The...
Charm quarks are effective probes used for the investigation of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. They are produced in hard scattering processes on a timescale shorter than the QGP formation time and experience the whole system evolution.
The measurement of charm-baryon production, and in particular the baryon-to-meson ratios, provides unique...
We present LHCb results on charmonia production in proton-lead collisions, using the data collected in 2016 at sqrt(s_NN) = 8.16 TeV nucleon-nucleon centre-of-mass energy, in the forward region (pseudorapidity between 2 and 5), covering forward (pPb configuration) and backward (Pbp configuration) rapidities. Measurements include prompt and from-b-decay components which are disentangled. The...
We redevelop the chiral kinetic theory (CKT) by exploiting the effective field theory method and find some disagreements at higher order of ($1/\mu$) from the earlier results. However, these disagreements are the same which have been pointed out by the off-shell effective theory formalism after identifying a cut-off. We address the discrepancies and by using the reparametrization invariance,...
Be based on Heavy Ion Collisions, I focus on the chiral anomaly effect eg:CME or CVE in magnetic hydrodynamics. Due to chiral anomaly ,there will be many special features ,I will introduce possible new wave models with the CVE in magnetic hydrodynamics.
We study the anomaly-induced effects of dense matter under rotation. We show that the chiral perturbation theory under rotation has the topological term that accounts for the chiral vortical effect. We find that, due to the presence of this new term, the ground state of QCD under rotation is the chiral soliton lattice (CSL) of the neutral pion or $\eta^{\prime}$ meson. This state is a periodic...
We investigate the influence of rotation on the chiral condensate in strongly interacting matter. We develop a self-consistent theoretical framework to study the inhomogeneous chiral condensate and the possible chiral vortex state in rotating finite-size matter in four-fermion interaction theories. For sufficiently rapid rotation, the ground state can be a chiral vortex state, a type of...
Quarkonia are excellent probes for studying the properties of quark-gluon plasma formed in relativistic heavy-ion collisions at RHIC. In order to fully understand the observed suppression of quarkonium production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV, it is essential to understand well the cold nuclear matter (CNM) effects on the quarkonium production. Collisions of p+Au at...
Experiments at RHIC and the LHC have lately reported intriguing results that indicate the presence of collectivity in small collision systems. The first hints originated from two-particle azimuthal correlations studies. The charge dependent part of such correlations is studied using the balance function in the relative pseudorapidity (∆η) and azimuthal angle (∆φ) of the particle pair. This...
We reconstruct the freeze-out state of the fireball produced in central Au+Au or Pb+Pb collisions in the energy range from 7.7 GeV up to 2760 GeV per colliding nucleon pair. The data stem from the RHIC beam energy scan programme and from the LHC. Transverse momentum spectra of protons, antiprotons, charged pions and kaons have been fitted. Blast-wave model is used. Resonance decays are fully...
Validation of the Chiral Magnetic Effect (CME) in the quark-gluon plasma (QGP) produced in heavy-ion collisions can provide key insights into anomalous transport in QGP and the connections between chiral symmetry restoration, axial anomaly and gluonic topology. Recently, a charge-sensitive correlator, $\mathrm{R_{\Psi_m}(\Delta S)}$ [1], designed to discern between background- and CME-driven...
In this work, we have presented the collision energy, multiplicity and system size dependence of chemical freeze-out parameters such as chemical freeze-out temperature ($T_{\rm ch}$) and strangeness saturation factor ($\gamma_{s}$). These parameters are obtained by analysing the particle ratios at different Large Hadron Collider (LHC) energies using statistical thermal model (THERMUS). Here,...
Cumulants of net charge fluctuations and their correlations at vanishing values of the charge chemical potentials ($\mu_{B,Q,S}=0$) provide the basis for Taylor expansions of various thermodynamic observables at non-zero values of the chemical potentials. At $\mu_{B,Q,S}=0$ continuum extrapolated results for these cumulants can directly be compared with charge fluctuations and correlations...
We study the production of pions, kaons, and (anti-) protons in A Multi Phase Transport (AMPT) Model in Au+Au collisions at $\sqrt{s_{NN}}=$ 7.7, 27, and 200 GeV. We present the centrality and energy dependence of bulk observables such as invariant yields as a function of transverse momentum $p_T$, particle yields $dN/dy$, average transverse momentum $\langle p_T \rangle$ and various particle...
Commonly, only low-$p_{\perp}$ sector is used to infer the features of initial stages before QGP thermalization. On the other hand, recently acquired wealth of high-$p_{\perp}$ experimental data paves the way to utilize the high-$p_{\perp}$ particles energy loss in exploring the initial stages. However, the results of such explorations are up to now either inconclusive or questionable. We here...
We present our continuum extrapolated lattice QCD results for the cross-correlators of baryon number, electric charge and strangeness, and compare them to calculations from the Hadron Resonance Gas (HRG) model with the most up-to-date hadronic spectrum. We analyze the contributions to these observables from hadronic correlations and self-correlations, and their relation to experimentally...
We present our results on genuinely 3+1D simulations of the Glasma in heavy ion collisions. By incorporating nuclei with finite thickness along the beam axis, we naturally break boost invariance and obtain Gaussian-like rapidity profiles of energy densities already at the tree level [1]. The profiles resemble strong coupling results and agree surprisingly well with experimental data of pion...
Charm and beauty are heavy quarks with observed masses of
1.28 GeV/c 2 and 4.18 GeV/c 2 respectively. They are produced
in initial hard scattering processes. Due to their small
formation time (∆t~0.1 fm/c) as compared to the formation
time of QGP ( ∆t~0.3 fm/c) at the LHC, they experience all the
stages occuring during the time evolution of the hot and dense
medium produced in heavy-ion...
Heavy quarks (charm and beauty) are effective probes to investigate the properties of the hot and dense strongly-interacting medium created in heavy-ion collisions as they are produced in high-energy hard partonic scattering processes occurring in the early stages of the collision. Due to their long life time, they probe all the stages of the medium evolution interacting with its constituents...
The production of charm quarks occurs predominantly in hard scattering processes in the earliest stages of a heavy-ion collision, and due to their relatively long lifetimes they experience the full evolution of the system. In ALICE, charmed mesons ($D^0$,$D^+$,$D^{*+}$ and $D_{s}^{+}$) are reconstructed in their hadronic decay channels, allowing the full kinematic information of the original...
Because of their early production, charm quarks are sensitive to the entire evolution of the system created in ultra-relativistic collisions of heavy ions. In particular, charm quark elliptic flow (v2) is a valuable tool for study of charm transport in the quark-gluon plasma (QGP). Recent results from the STAR experiment show that in 10-40% central Au+Au collisions at the top RHIC energy the...
Interactions between hard partons and the quark-gluon plasma range from frequent soft collisions to rare large angle scatterings. The larger number of soft interactions makes possible an effective stochastic description of parton-plasma interactions in terms of drag and diffusion transport coefficients [1]. We build on the methodical division between soft and hard parton-plasma interactions...
The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, aims to explore the quantum chromodynamics phase diagram for highest baryon densities.
One of the core detectors of CBM is the Silicon Tracking System (STS). The STS is the key detector for measuring the momentum and tracks of up to 1000 charged particles...
The Compressed baryonic matter (CBM) experiment at the future acceleratorFacility for anti-proton and ion research (FAIR) in GSI Germany aims to explore the QCD phase diagram in the very high net-baryon density. The Muon Chamber (MuCh) system would facilitate detection of probes like charmonium (J/ψ) and low mass vector mesons (LMVM) via di-leptonic decay channel. The CBM ...
In J-PARC E16 experiment, for the first beam time in the coming February 2020, the sophisticated detector system for measuring hadron spectra via $e^{+}$ $e^{-}$ pair decay, for example $\phi$ $ \rightarrow $ $e^{+}$ $e^{-}$, is being installed and commissioned. In addition to these detectors, hadron identification detector using time-of-flight technique with MRPC devices, is under...
Based on the state-of-the-art Monolithic Active Pixel Sensor (MAPS) technology, the silicon pixel detector has been successfully applied in the STAR Heavy Flavor Tracker (HFT) for the first time since early 2014. The HFT allows precise measurements of open heavy flavor hadron production in heavy-ion collisions over a wide range of transverse momentum at RHIC. After the 2$^{\rm{nd}}$ long...
Dielectron production is suggested as an excellent probe of the hot, dense and strongly interacting medium (QGP) created in relativistic heavy-ion collisions due to their minimal interactions with the medium and the final state hadrons. Dielectrons can be produced at different evolution stages of the collision system. Different invariant mass ranges are sensitive to different physics...
Dielectrons are excellent probes of the Quark-Gluon Plasma (QGP) created in high-energy heavy-ion collisions. Because they can be produced at all stages of the collision system evolution and do not interact with the medium strongly, dielectrons carry the information from the initial stage to the final stage. In the low mass region (LMR, $\rm M_{ee} < M_{\phi}$), the mass spectra of vector...
The medium generated by non-central nuclear-nuclear collision would have a large angular momentum. Due to the spin-orbit coupling, spin directions of particles formed by recombining quarks from the plasma could reflect the spin direction aligned with the angular momentum of the system. Global polarization is expected to lead to the understanding of the physical properties of QGP because it is...
Oskari Saarimäki for the ALICE collaboration
We present the dijet invariant mass distribution in pp and p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV measured by ALICE. We study the dependence of the dijet invariant mass on event multiplicity in both collision systems, to explore cold nuclear matter effects or possible medium modifications in small collision systems. We measure...
Rapidity-odd component of directed flow ($v_{1}$) measurement at various beam energy gives a new insight on the properties of the medium created in heavy-ion collisions. Both hydrodynamic and nuclear transport models indicate that $v_{1}$(y) is sensitive to the details of expansion during the early stages of collision fireball. In this poster, we will present directed flow ($v_{1}$) as a...
Micropattern gaseous detectors (MPGDs) are a group of modern gaseous ionizing detectors consisting of microelectrode structures developed to overcome many of the difficulties of traditional gaseous detectors such as multiwire proportional chambers. The gas electron multiplier (GEM) is one of the most prolific MPGDs currently in use and slated to be used for many future detectors or current...
We examine the relativistic perfect fluid limit,
defined as the fastest possible local equilibration, in a medium with
polarizeability, defined as a non-zero local equilibrium partition of
angular momentum into spin and vorticity.
We show that the Lagrangian approach is best suited to analyzing this situation, as
it can be used to efficiently avoid issues such as the breakdown
of...
DREENA framework is based on our dynamical energy loss formalism, which takes into account finite size, finite temperature QCD medium consisting of dynamical (moving) partons. Both radiative and collisional energy losses are calculated under the same theoretical framework in the dynamical energy loss formalism, which is applicable to both light and heavy flavor observables. We generalized the...
The quark gluon plasma (QGP) produced in high-energy nuclear collisions is known to behave like a perfect fluid. In hydrodynamic simulations at RHIC and the LHC energies, space-time evolution of the QGP is usually described in expanding coordinates. On the other hand, in SPS and RHIC-BES energies, Cartesian coordinates are used for effective description of hydrodynamic expansion. However, the...
We study the far-from equilibrium shear viscosity as present in the early stage of a heavy-ion collision. Our investigation is based on applying the AdS/CFT correspondence to a time-dependent Vaidya spacetime. A generalization of the entropy density to the non-equilibrium regime is necessary for a consistent description. Throughout the evolution, we observe significant deviations in the shear...
In a collision of two identical heavy-ions, the participant zone formed from the overlapping region of the two colliding nuclei contains unequal number of nucleons from each nucleus due to fluctuations. Consequently, the participant zone has a non-zero momentum in the centre of mass frame of the colliding nuclei, causing a longitudinal asymmetry. Using data in Pb-Pb collisions at centre of...
Electrical properties of QCD plasma is an important tool to understand the behaviour of strongly interacting matter in different physical conditions. It will help us to understand the effect of electromagnetic interaction with strongly interacting QCD plasma. Recently, it has been shown that a strong magnetic field is created during heavy ion collisions. Thus it is interesting to study the...
At the early stage of heavy ion collisions, non-trivial topologies of the gauge fields can be created resulting in an imbalance of axial charge density and eventually separation of electric charges along the direction of the magnetic field produced in such collisions. This process is called the chiral magnetic effect (CME). In this work we implement such a charge separation at the partonic...
It is reported recently that an intriguing behavior of the anisotropic flow coefficients in ultra-central Pb-Pb collisions at the LHC. Elliptic flow in ultra-central collisions is driven mainly by fluctuations rather than collision geometry. Therefore, magnitudes of elliptic flow and triangular flow coefficients are almost identical. Some hydrodynamic models, which have been successful in...
Electromagnetic fields produced in relativistic heavy-ion collisions are affected by the asymmetry of the projectile-target combination as well as the different initial configurations of the nucleus.
In this study, the results of the electric and magnetic fields produced for different combinations of ions, namely $^{12}$C + $^{197}$Au, $^{24}$Mg + $^{197}$Au, $^{64}$Cu + $^{197}$Au, and...
Measurements of electroweak bosons produced in Pb+Pb collisions as well as photon and jet production in p+Pb collisions are of great interest to understanding initial state effects. These channels are sensitive to a broad set of physics effects such as high-precision test of the binary collision scaling expected in Pb+Pb, the modification of the parton densities in nuclei, the onset of...
Measurements of heavy-flavor hadron production and elliptic flow ($v_{2}$) provide unique and indispensable information for understanding the properties of the QGP. Recent STAR measurements indicate that in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV $D^{0}$ mesons develop large $v_{2}$ similarly as light-favor hadrons, implying that charm quarks interact strongly with the...
Charm and beauty quarks (heavy flavours) are produced in hard scattering processes in the early stages of heavy-ion collisions, and propagate through the hot and dense QCD matter (QGP) produced as a consequence of the collision. Therefore, they are sensitive probes to characterize the QGP properties.
The measurement of the elliptic flow (${v_{2}}$) of open heavy-flavour particles at low...
Forward hadron lead/scintillator sampling calorimeter (Projectile Spectator Detector, PSD) consisting of 44 longitudinally segmented modules is developed and already constructed for the future Compressed Baryonic Matter (CBM) experiment at FAIR. The original approaches in the energy calibration with cosmic muons and in the signal analysis are proposed. The longitudinal segmentation of...
Strangeness enhancement in central heavy-ion collisions (A+A) relative to proton-proton interactions (pp) has long been a well-recognized signature for QCD deconfinement or the formation of Quark Gluon Plasma (QGP). The energy scan program at the Relativistic Heavy Ion Collider (RHIC) in BNL or at CERNs' Super Proton Synchrotron (SPS) have presented evidence that are typical of the enhanced...
Studies of collisions of highly accelerated ions are the key to understand the creation of quark matter. Experimental physicists put considerable effort in collecting information characterizing the various processes occurring during such collisions. In order to describe such scenarios, complex models have been constructed, one of them being the EPOS approach. It applies Parton-based...
An interesting strong dependence on charged-particle multiplicity ($n_{ch}$) of $J/\psi$ and $\Upsilon$ production at the LHC and $J/\psi$ at RHIC has been observed. These measurements provide basic information about particle production mechanisms, especially on an interplay between hard and soft processes (multiple parton interactions, string percolations, color reconnection). In order to...
Collision centrality for large heavy ion systems is well defined
both theoretically and experimentally, but the same is not necessarily
true when very asymmetric systems, like p/d+A, collide. In light of
some surprising result on the centrality dependence of high transverse
momentum observables in p/d+A collisions at RHIC and LHC,
the very concept of the geometrically inspired centrality...
Elliptic flow is one of the most important observables in the relativistic heavy ion collisions. It can provide us opportunities to study the early evolution of the expanding system. In this poster, we will present elliptic flow of identified particles ($\pi^{\pm}$, $K^{\pm}$, $p$($\bar{p}$), $K_{S}^{0}$, $\Lambda$($\bar{\Lambda}$), $\phi$, $\Xi^{-}$($\bar{\Xi}^{+}$),...
The study of hadronic resonances such as $\rm{K}^{*}$ and $\phi$ provides a unique tool to investigate the interplay of re-scattering and regeneration effects in the hadronic phase of heavy-ion collisions. As the $\rm{K}^{*}$ has a lifetime comparable to the lifetime of the hadronic phase, one would expect to observe the effects of re-scattering and regeneration processes in the measured...
Recent observations of Quark-Gluon Plasma (QGP)-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrants an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for possible formation of QGP droplets. A double differential study of the identified particle production and freeze-out scenario of ...
The interplay between the magnetic and electric field in heavy-ion collisions at high energy results in the charge separation, the phenomenon is known as Chiral Magnetic Effect (CME). Event-by-event charge separation measurements in Pb-Pb collisions at √sNN = 5.02 TeV will be presented. The sum of positive charge fraction on left side and negative charge fraction on right side of the dumbbell...
In relativistic heavy-ion collisions, a strongly interacting medium known as the Quark Gluon Plasma (QGP) is produced. Quarks and gluons from incoming nuclei collide to produce partons at high momenta early in the collisions. By fragmenting into collimated sprays of hadrons, these partons form `jets'. The resulting jets, which in vacuum are well understood within the framework of...
We present a full simulation of evolving charge correlations in heavy-ion collisions using a combination of hydrodynamics and a hadronic Boltzmann cascade to model the underlying system evolution. We compute the charge balance functions (CBFs) in both rapidity and azimuthal angle and observe their dependence on several phenomenological parameters in our model. In particular, we observe...
Exploration of the rich structure of the QCD phase diagram is an important topic in the RHIC beam energy scan program whose ultimate goal is to discover the critical endpoint. Investigation of the space-time structure of hadron emissions at various phase transition points using Bose-Einstein correlation of identical bosons will provide insight on the location of the critical endpoint. PHENIX...
The extraction of thermal freezeout parameters from measured hadron yields
and their higher moments have met with considerable success within the frame-
work of hadron resonance gas models. The standard assumption in such studies
is to consider a constant freezeout parameter set which is extracted by chi-square
fit to data. However, in reality, thermal conditions at freezeout need not be...
We study [1] the suppressions of high transverse momentum single hadron and dihadron productions in high-energy heavy-ion collisions based on the framework of a next-to-leading-order perturbative QCD parton model combined with the higher-twist energy loss formalism [2,3]. Our model can provide a consistent description for the nuclear modification factors of single hadron $R_{AA}$ and dihadron...
Within a multi-phase transport model with string melting scenario, jet transport parameter $\hat{q}$ is calculated in Au+Au collisions at $\sqrt{s_{NN} } $= 200 GeV and Pb+Pb collisions at $\sqrt{s_{NN} } $= 2.76 TeV. The $\hat{q}$ increases with the increasing of jet energy for both partonic phase and hadronic phase. The energy and path length dependences of $\hat{q}$ in full heavy-ion...
In recent years, factorization breaking of flow coefficients in transverse momentum has been measured by CMS Collaboration [1] to understand the transport properties of QGP. The factorization ratio $r_n$ measured in Pb + Pb collisions at LHC represents the decorrelation of the event plane angle in different transverse momentum regions. When $r_n = 1$, which implies the coincidence of the...
“Hybrid Hadronization” is a new Monte Carlo package to hadronize systems of partons. It smoothly combines quark recombination applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems, following the picture outlined by Han et al. [PRC 93, 045207 (2016)]. Hybrid Hadronization integrates with PYTHIA 8 and can be applied to...
We explore the directed, elliptic, triangular and quadrangular flow of deuterons in Au+Au reactions at a beam energy of 1.23 AGeV within the UrQMD approach. These investigations are of direct relevance for the HADES experiment at GSI that has recently presented first data on the flow of light clusters in Au+Au collisions at 1.23 AGeV. To address the deuteron flow, UrQMD has been extended to...
LHCb has the unique capability to study collisions of the LHC beams on fixed targets. Internal gas targets of helium, neon and argon have been used so far to collect samples of proton- and Pb-gas collisions corresponding to integrated luminosities up to 0.1 pb$^{-1}$. Results on open and hidden charm productions will be presented, which can provide crucial constraints on cold nuclear matter...
for the ALICE Collaboration
Anisotropic flow provides important constraints on the initial conditions and the transport properties of the medium created in heavy-ion collisions. The flow coefficients of higher order harmonics are sensitive to viscous damping [1] and might hinder so-called "acoustic peaks" in flow harmonic power spectrum in analogy to Cosmic Microwave Background in...
Near the QCD critical point (CP), critically slow processes can invalidate the conventional (dissipative) hydrodynamic description, which simply integrates out all non-hydrodynamic modes. We explore the critical dynamics near the QCD CP with the novel Hydro+ framework [1] which extends the conventional hydrodynamic description by coupling it to additional explicitly evolving slow modes. Their...
Recently physics of thermal fluctuations of hydrodynamic fields, namely the hydrodynamic fluctuations, in high-energy nuclear collisions are actively discussed. In this talk I will discuss new modification terms [1] in fluctuation-dissipation relation (FDR), which determines the power of hydrodynamic noise fields, and also discuss its importance in the point of view the fluctuation theorem...
It is well established that the spatial asymmetries of the overlap region in the initial state of a heavy ion collision, together with their fluctuations, are quite faithfully translated into final-state momentum anisotropies by a fluid-dynamical evolution. We investigate the relationship between initial-state eccentricities and final-state anisotropic flow harmonics for a simplified...
In heavy ion collisions, the transverse size or centrality of the QGP is not a boost-invariant concept. Due to forward-backward multiplicity fluctuations, the centrality of the system, defined as $N_{\mathrm{ch}}$ in a given $\eta$ range, also fluctuates in the longitudinal direction. This longitudinal fluctuation leads to decorrelation of centrality along $\eta$, analogous to the...
The observation of multi-particle azimuthal correlations in high-energy small-system collisions has led to intense debate on its physical origin between two competing theoretical scenarios: one based on initial-state intrinsic momentum anisotropy (ISM), the other based on final-state collective response to the collision geometry (FSM). To complement the previous scan of asymmetric collision...
The Generalized High Twist approach has been established to investigate the radiative parton energy loss in deeply inelastic scattering off a large nucleus. The parton undergoes multiple medium parton scatterings and medium-induced radiation after scattering with the virtual photon. In the calculation of radiative energy loss, we relax the approximation in High Twist approach that the radiated...
Fluctuations in physics observables and flow effects in heavy-ion collisions have been topics of particularly interest in recent years as they may provide important signals regarding the formation of quark-gluon plasma, the existence of a critical point and the evolution of the system. Moreover, the fluctuations and correlations measured in the final stage have their sources at least partly ...
We study the medium-induced gluon emission process experienced by a hard jet parton propagating through the dense nuclear matter in the framework of deep inelastic scattering off a large nucleus. We work beyond the collinear rescattering expansion and the soft gluon emission limit, and derive a closed formula for the medium-induced single gluon emission spectrum from a heavy or light quark jet...
Motivated by the recent lattice result, we study the Landau gauge gluon propagators in dense two-color QCD at quark chemical potential. In order to take into account the non-perturbative effects in the infrared regime, we use the massive Yang-Mills theory which has successfully described the gluon and ghost propagators in the Landau gauge within the one-loop approximation. We couple quarks to...
Hadronic resonances are interesting probes of the hot and dense matter created in heavy-ion collisions. Due to their short lifetimes, resonances
are useful tools to understand the particle production mechanisms and the properties of the hadronic phase. Resonance yields are expected to be modified due to the interaction of their decay daughters within the hadronic medium via the re-scattering...
In this talk, we will review the basics of 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP) and highlight some phenomenological comparisons with experimental data at both 2.76 TeV and 200 GeV. We will then present preliminary comparisons of the femtoscopic Hanbury-Brown-Twiss (HBT) radii using aHydroQP. We will show comparisons of the HBT radii and their ratios between aHydroQP and the...
Effective Field Theories (EFTs) provide a systematic framework in which all terms consistent with the symmetries up to a specific mass dimension are written down in the lagrangian. We explore the consequence of the assumption that a fermionic EFT describes the QCD crossover.
This EFT was analyzed for zero quark number chemical potential ($\mu=0$) in Ref. [1] considering all chirally...
In relativistic heavy-ion collisions, quark-gluon plasma can have a supersonic motion in the longitudinal direction. The quark-gluon plasma also has barotropic equation of state, negligibly small $\eta/s$ ratio, and irrotational velocity profile (specially in the central collisions, where there is no net initial angular momentum). Thus it can be used to construct an analog model of gravity,...
The primary source of high transverse momentum (>4-5GeV/c) direct photons is the initial hard scattering of partons, specifically the quark-gluon Compton scattering process. This has been validated not only in hadron-hadron, but also in heavy ion collisions (see for instance PRL 109 (2012) 152302), where the observed yields were proportional, as expected, to the number of binary...
The gradient expansion solutions to hydrodynamic equations are found to be divergent in many cases. The application of resurgence theory rescues the divergent series solutions and reproduces hydrodynamic attractors in Bjorken flow[1,2] and Gubser flow[3,4]. In this talk, I will first present my result of Borel-resummed hydrodynamics in a different situation, a viscous fluid system that...
The main goal of the CBM experiment at FAIR is to study the behavior of nuclear matter at very high baryonic density. This includes the exploration of the high density equation of state, search for the transition to a deconfined and chirally restored phase, critical endpoint. One of the promising diagnostic probes for these new states is the enhanced production of multi-strange...
Identified light flavour particles, such as the $\pi$, K, $\phi$ mesons and the p, $\Lambda$, $\Xi$ baryons, constitute interesting probes to investigate the collective behaviour recently observed in small collision systems. The underlying mechanisms of light flavour production are currently not well understood, and the mechanisms are explained in the framework of different models. pQCD...
Heavy-flavor quarks created in ultra-relativistic heavy-ion collisions are mostly produced in hard QCD processes during the early stages of the reaction and their production is largely unaffected in the later
stages. They interact with the hot nuclear matter throughout the whole evolution of the systems via semi-hard and soft processes such as energy loss via gluon radiations and collisions....
The inclusive $J/\Psi$ production by direct and resolved photoproduction in the $\gamma p$ scattering is calculated based on the nonrelativistic quantum chromodynamics (NRQCD) factorization formalism, which is in good agreement with the experimental data of total cross section distribution of heavy quarkonium production at HERA. Then we extend the formalism including the direct and resolved...
The Quark Gluon Plasma (QGP) is a state of matter at extremely high energy density, where the quark and gluon constituents of nucleons become deconfined. Although there is strong evidence at RHIC and the LHC that the QGP is created in A+A collisions, it was initially assumed to be absent in smaller systems, such as p+p and p+A collisions. However, the observation of flow-like correlations in...
We study the fluctuation of shape-deformation as currently implemented in MC-Glauber-like models and their consequences on the magnitude of initial-state eccentricities. We show that for both deformed and spherical colliding species, there are large fluctuations in the deformation that emerge event by event. We characterize these deformations with the ratio of the largest and smallest...
The unambiguous observation of a Chiral Magnetic Effect (CME)-driven charge separation is the core aim of the isobar program at RHIC consisting of ${^{96}_{40}}$Zr+${^{96}_{40}}$Zr and ${^{96}_{44}}$Ru+${^{96}_{44}}$Ru collisions at $\sqrt {s_{\rm NN}}\!=\!200$ GeV.We quantify the role of the isobars spatial distributions on both the eccentricity and the magnetic field strength within a...
Many great efforts have been made to investigate the Chiral Magnetic Effect (CME) and Chiral Magnetic Wave (CMW), which reply on the existence of extremely large electromagnetic fields in relativistic heavy-ion collisions.
However, the current main difficulty of measuring the CME signal is some backgrounds which we do not understand clearly. To isolate the influence of those backgrounds,...
In this talk, I will present a new procedure for dynamically generating conserved charges (baryon number, strangeness, and electric charge) to supplement an arbitrary initial condition for ultrarelativistic heavy ion collisions. This algorithm, which we denote ICCING (Initial Conserved Charges in Nuclear Geometries), treats an initial distribution of energy density as if it were composed...
The lifetimes of short-lived hadronic resonances are comparable to the hadronic phase of the medium produced in high-energy collisions. Thus, these resonances are sensitive to the re-scattering and regeneration processes in the time interval between the chemical and kinetic freeze-out, which might affect the resonance yields. In addition, event shape observables like transverse spherocity are...
One of the important results of the LHC Run 1 was the observation of an enhanced production of strange particles in high multiplicity pp and p-Pb collisions at 7 and 5.02 TeV, respectively. A smooth evolution of yields of strange particles relative to the non-strange ones with event multiplicity has been observed in those systems. Results from Run 2 at the top LHC energy allows us to improve...
To explain the underlying mechanisms involved in particle production and the properties of the strongly interacting nuclear matter produced in high multiplicity p+p collisions, one can use two particle azimuthal correlation method as an important tool. We present here measurements of two particle azimuthal correlation with neutral pion$(\pi^0)$, neutral kaon$(k^0)$ and proton as trigger...
A Time Projection Chamber is the main tracking system for the proposed sPHENIX experiment at RHIC. It will measure space points of charged tracks, which provide the needed momentum resolution to separate the Upsilon states in decays to electrons and positrons.
The strong magnetic field of the solenoid previously used in the BaBAR experiment, a Neon-based fast gas mixture, and an electric...
Direct photons from Compton and annihilation hard processes, produced in hard scatterings of partons from incoming nucleons, are unique colourless probes of QCD processes. The measurement provides a handle for testing perturbative QCD predictions and constrain the parton distribution functions.
In this contribution, we present the measurements of isolated photon cross section in pp collisions...
Isolated Photon-Hadron Correlations in pp and p--Pb Collisions at $\sqrt s_{\rm NN}$ = 5 TeV in ALICE.
Fernando Torales Acosta on behalf of ALICE collaboration.
The measurement of isolated photon-tagged correlations of jets and jet fragments is a promising channel for the study of partonic energy loss in heavy-ion collisions. We use a combination of isolation and electromagnetic...
In the early and hottest phase of nucleus-nucleus collisions the formation of a Quark-Gluon Plasma (QGP) is expected. Several QGP induced effects, such as the melting of charmonium states due to color screening or the recombination of uncorrelated charm and anti-charm quarks, can influence charmonium yields. Recent ALICE measurements of charmonium nuclear modification factor in Pb--Pb...
The understanding of cold nuclear matter (CNM) effects are essential to study the properties of a state of deconfined quarks and gluons, the quark-gluon plasma, created in relativistic heavy-ion collisions. CNM effects can be studied in p-Pb collisions.
Furthermore, some results in high-multiplicity p-Pb collisions suggest collectivity similar to that in Pb-Pb collisions. For J/$\psi$...
Polarization is a key observable to determine the quarkonium production mechanism in hadronic elementary collisions. Its very small value measured at the LHC has been challenging the commonly-used theoretical models and it still represents a major standing issue in the field.
On the other hand, phenomenological studies have shown that primordial quarkonium in heavy-ion collisions can be...
The cross section for coherent J/$\psi$ photonuclear production in ultra-peripheral collisions (UPC) at the LHC is sensitive to the low x behaviour of the gluon distribution function of the interacting lead nuclei and provides important constraints on the initial stages in heavy ion collisions.
The measurement of this process by ALICE in Pb-Pb UPC at forward rapidity using Run 2 data at...
In high-energy (proton-proton) pp collisions, there can be a substantial contribution from Multi-Parton Interactions (MPI) in particle production mechanisms. In this case, several interactions at the partonic level occur in a single pp collision and this implies a correlation between the particle production and the total event multiplicity. At LHC energies, MPI might occur at hard momentum...
The measurement of jet shapes such as the angularity, the momentum dispersion and the difference between the leading and subleading jet constituents track momentum will be presented. The measurements were done in pp collisions at $\sqrt s$ = 5 TeV and will be compared to previous measurements by ALICE at $\sqrt s$ = 7 TeV. These jet structure observables probe the radiation pattern of jets....
In this talk the second major software release of the JETSCAPE collaboration will be described. The Jet Energy-loss Tomography with a Statistically and Computationally Advanced Program Envelope (JETSCAPE) Collaboration is developing a complete event generator for heavy ion collisions to be used by the wider community. In this talk we highlight the performance of the year-2 release of the...
Several experimental observables, sensitive to the evolution of the system after nuclear collisions, reveal important information about the properties of the QGP. Among such observables is the production rate of strange quarks, which were originally predicted to be produced with higher probability in a QGP scenario with respect to a pure hadron gas scenario. Studies of strangeness production...
The dynamical models near the critical point are important tools to study the critical phenomena for RHIC BES program. However, the related model calculations depends on various parameters and inputs. In this talk, I will focus on the universal behavior of the dynamical evolving systems near the critical point, which is insensitive to various parameters and input in the model calculations.
...
First, we recall that close to the chiral limit, and below the critical temperature, the long wavelength effective theory of QCD is not ordinary hydrodynamics, but SU(2)xSU(2) superfluid hydrodynamics (Son 2000). In this theory the usual hydrodynamic variables such as energy are momentum are augmented by long wavelength pions. When the pion is massive, the effective theory reduces to normal...
$\Lambda$ and $\bar{\Lambda}$ polarization in heavy-ion collisions at BES RHIC energies is studied within the microscopic transport model UrQMD. Two approaches, (1) thermal and (2) axial anomaly approach, are considered. We trace the formation and space-time evolution of vorticiity and helicity patterns in details. This study demands a complex analysis of the fireball conditions including...
In high energy nuclear collisions, light nuclei production is sensitive to the baryon density fluctuations and thus can be used to study the QCD phase transition. For example, the neutron density fluctuation can be extracted from the yield ratio of proton, deuteron and triton, $N_{\mathrm{p}} N_{\mathrm{t}} / N_{\mathrm{d}}^{2}$, which may provide a method to study critical phenomena in...
Principal Component Analysis (PCA) is a mathematical tool that can capture the most important information (variance) in data. Recently, CMS collaboration applied the PCA technique to analyze the data in Pb+Pb collisions, and a non-zero subleading mode has been extracted and interpreted as arising from subleading eccentricity [1][2]. In this talk, we study the performance of PCA method in the...
Spin polarization of $\Lambda$ hyperon has been observed by STAR in non-central heavy-ion collisions [1,2,3]. Among these measurements, the global polarization reflects the bulk-averaged value of the vorticity, while the local polarization probes more detailed structure of the vorticity field.
We have studied the $\Lambda$ polarization in heavy-ion collisions using a multi-phase transport...
One of the main aims of beam energy scan (BES) program at relativistic heavy ion collider (RHIC) is to locate the position of critical point in the ($T-\mu_B$) plane of QCD where the first order transition ends and cross over transition begins. Here $T$ denotes temperature and $\mu_B$ stands for baryonic chemical potential.At the critical point, quantities like specific heat and susceptibility...
The presence of coherence in pion emission will suppress the strength of the final-state pion HBT correlations. The recently observed significant pion HBT suppressions in both Pb-Pb and pp collisions at the LHC indicate the pion emissions may be partially coherent in such violent collisions. In this talk we will show that the coherence in particle emission can give rise to a remarkable...
The High Acceptance DiElectron Spectrometer (HADES) and the Compressed Baryonic Matter experiment (CBM) are dedicated to study strongly interacting matter at high baryon densities and moderate temperatures. Being penetrating probes, dielectrons are a key observable to get direct access to the fireball.
Currently the HADES experiment is located at SIS 18 at GSI, Darmstadt and will be moved...
In high energy heavy-ion collisions, the strong electromagnetic (EM) fields of the nuclei can produce energetic, high-density photon fluxes, leading to photon-induced interactions. Recently, significant enhancements of $e^{+}e^{-}$ pair and J/$\psi$ production at very low transverse momentum ($p_{T}$) were observed by the STAR [1, 2] and ALICE [3] collaborations in peripheral hadronic A+A...
Low-mass dielectrons play a key role in the understanding of the chiral-symmetry restoration and in the study of the Quark-Gluon Plasma (QGP) created in relativistic heavy-ion collisions. In the intermediate-mass region, the measurement of thermal dielectrons from the QGP is nevertheless very challenging at the LHC due to the dominant contribution of e$^{+}$e$^{-}$ pairs from open-charm and...
The measurement of low-mass $e^+e^-$ pairs is a powerful tool to study the properties of the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. Since such pairs do not interact strongly and are emitted during all stages of the collisions, they provide information about the full time evolution and dynamics of the medium created.
Measurements in pp collisions are the...
Reconstructing the jet transverse momentum is a challenging task, particularly in heavy-ion collisions due to the large fluctuating background from the underlying event. While the standard area-based method effectively corrects for the average background, it does not account for region-to-region fluctuations. These residual fluctuations are handled in an unfolding procedure following the...
Recent STAR measurements of global hyperon polarization in AuAu Collisions at the Relativistic Heavy Ion Collider (RHIC) have attracted significant interest and generated wide enthusiasm. The data present an intriguing puzzle, showing a difference in the global spin polarization between hyperons and anti-hyperons, especially at relatively low collision beam energy. One possible cause of this...
The main goal of NICA/MPD is to investigate the hot and dense baryonic matter in heavy-ion collisions over a wide range of atomic masses, from $Au+Au$ collisions at a center-of-mass energy of $\sqrt{s_{NN}} = 11GeV$ (for $Au^{79+}$) to proton-proton collisions with $\sqrt{s_{pp}}= 20GeV$.
Electromagnetic calorimeter (ECal) is an important detector of the MPD to identify electrons, photons...
Owing to their large mass, charm quarks are predominantly produced through initial hard scatterings in heavy-ion collisions. Therefore, they can serve as penetrating probes to study the intrinsic properties of the hot medium created in heavy-ion collisions. However, Cold Nuclear Matter (CNM) effects can also affect the charm quark production in nuclear collisions with respect to p+p...
The ALICE detector at the Large Hadron Collider (LHC) is optimised for the inverstigation of the Quark-Gluon Plasma (QGP) created in heavy-ion collisions. Charm quarks are effective probes to elucidate the properties of the QGP. They are dominantly produced at the initial stage of the collisions via hard partonic scattering processes and experience the whole evolution of the...
Charm quarks, owing to their large mass, are predominantly created through initial hard scatterings in relativistic heavy-ion collisions and thus are ideal probes to study early time dynamics of these collisions. Recent results from STAR show that the slope of $D^{0}$ mesons directed flow ($v_{1}$) versus rapidity is about 25 times larger than that of charged kaons, providing important...
The $\phi$ vector mesons have much smaller hadronic cross section which makes them less influenced at late-stage interactions than other hadrons [1-4]. Thus their anisotropies like the elliptic flow should be small if the system is always in a hadronic phase. This, in turn, makes $\phi$ meson $v_2$ especially sensitive to the energy where quark-gluon plasma turns off. Measurements from STAR at...
Due to their large masses, heavy quarks are produced in the early stages of relativistic heavy-ion collisions via initial hard scatterings. Therefore, they are considered as effective probes of the hot and dense Quark-Gluon Plasma (QGP) formed in such collisions and witness the full evolution of the QGP. In pp collisions, the measurement of charm and beauty hadron production cross-sections can...
In heavy-ion collisions, charm and beauty quarks are produced in the initial hard partonic scattering and interact with the hot and dense QCD matter (QGP).
Therefore, measurements of heavy-flavour production provide relevant information on the properties of the QGP. The QCD predicts that partons lose energy via collisions with the plasma constituents and via gluon radiation, and the magnitude...
One of the main goals of RHIC beam energy scan program is to search for the signature of the QCD critical point in heavy-ion collisions. It is predicted that the local density fluctuations near critical point exhibit power-law scaling, which can be probed with a intermittency analysis of the scaled factorial moments ($F_{q}$) for charged particles. The power-law behavior of $q^{th}$ order...
The measurement of jet shapes and their multiplicity dependence in pp collisions at LHC energies can provide insight on the production of jets and the interplay between jet fragmentation and event multiplicity in small colliding systems (pp,pA). In this contribution, we report the results on jet-shape measurements using the ALICE experiment in minimum bias pp collisions at $\sqrt{s}=$ 5, 7 and...
The charge asymmetry ($A_{\rm ch}$) dependence of the $\pi^{+}$ and $\pi^{-}$ elliptic flow difference, $\Delta v_{2}(A_{\rm ch})\equiv v_{2}^{\pi^{-}}(A_{\rm ch}) - v_{2}^{\pi^{+}}(A_{\rm ch})$, is sensitive to the Chiral Magnetic Wave (CMW). Previous measurements in 200 GeV Au+Au collisions by STAR indicated a positive $\Delta v_{2}(A_{\rm ch})$ slope and, in central and peripheral...
In heavy-ion collisions, the thermalized matter is tilted in the reaction plane as a function of rapidity, while the production profile of partons from hard scatterings is symmetric in rapidity [1]. This leads to a rapidity-odd asymmetry in the medium path length traversed by the hard partons and results in a rapidity-odd directed flow ($v_1$). Measurements of high-$p_{\mathrm{T}}$ hadron...
Fluctuations in conserved charges such as net charge (Q), net strangeness (S) and net baryon (B) are good probes of the QCD phase transition and the critical point [1]. The QCD-based models suggest that the moments of the conserved charge distributions are related to the correlation length of the system as: $\langle (\delta N)^{2} \rangle$ $\sim$ $\xi^{2}$, $\langle (\delta N)^{3} \rangle$...
We present the semi-inclusive measurement of charged jets recoiling from direct-photon and $\pi^0$ triggers in central Au+Au collisions at $\sqrt{s_\mathrm{NN}}=200$ GeV, using a dataset with integrated luminosity 13 nb$^{-1}$ recorded by the STAR experiment in 2014. The photon and $\pi^0$ triggers have $9<\rm E_{T}^{trig}<20$ GeV. Charged jets are reconstructed with the anti-$\rm{k_{T}}$...
ATLAS measurements of flow harmonics ($v_{n}$) in Xe+Xe collisions are presented. The measurements are performed using two-particle correlations, multi-particle cumulants and scalar product methods. The measurements are also performed using non-flow subtraction techniques -- recently developed for measurements in proton-nucleus and proton-proton collisions -- to improve the understanding of...
Heavy quarks are an excellent probe to study the strongly interacting quark-gluon plasma (QGP) created in high-energy heavy-ion collisions. They are mainly produced via initial hard partonic scattering processes and thus experience the entire evolution of the QGP medium. For J/$\psi$, a bound state of ${c}\bar{c}$ quarks, a strong suppression was seen in central collisions at the SPS and RHIC...
Cumulants of conserved quantities are the powerful tools to study the QCD phase structure. According to the Lattice Gauge Theory calculations, at vanishing baryon chemical potential ($\mu_{B}$) a "smooth crossover" for the transition from quark-gluon plasma to hadronic system occurs in heavy-ion collisions [1]. One of the possible experimental ways to search for the evidence is to analyze the...
Large uncertainty for initial geometry eccentricity has been found in small systems. Calculations which include subnucleon structure have been found substantially different with standard Glauber model calculations. This will make it difficult to address the physics origin of long-range angular correlations in small systems, which may come from the initial-state momentum correlations or...
The main goal of heavy-ion collisions is to study the deconfined phase predicted by quantum chromodynamics, the Quark Gluon Plasma.In the presence of the QGP, theories predict the existence of field configurations that could violate parity symmetry locally at a level that could be experimentally measured. In heavy-ion collisions, local parity violation manifests as charge separation along the...
Systematic investigation of charm and bottom productions and their modifications in heavy-ion collisions is crucial for understanding the parton energy loss mechanism inside the hot and dense medium. Electrons from semi-leptonic decays of open heavy-flavor hadrons can serve as a proxy for heavy quarks with the possibility of triggering on them during data taking to gain statistics.
The...
To study the nature of the quark-hadron phase transition, it is important to investigate the space-time structure of the hadron emission source in heavy-ion collisions. Measurements of HBT correlations have proven to be a powerful tool to gain information about the particle emission region. In this study, Levy fits were performed to the measured one-dimensional two-pion correlation functions...
Measurement of longitudinal flow decorrelations in Xe+Xe collisions involving two- and four-particle correlations for elliptic, triangular and quadrangular flow are presented. The strength of the decorrelation are found to be different from that in Pb+Pb for either the same centrality or Npart. The four-particle decorrelation is found to not factorize as product of two-particle...
Heavy quarks (i.e charm and beauty quarks) are effective probes to investigate the properties of the hot, dense and strongly-interacting medium, known as the Quark-Gluon Plasma (QGP), formed in ultra-relativistic heavy-ion collisions. Due to their large masses, they are produced in the initial stages of the collision via hard partonic scatterings and hence, they experience the full evolution...
The sPHENIX experiment will study the QGP properties with heavy bottom quark jets (b-jets) produced in high-energy heavy ion collisions, in the challenging low-pT regime, where the expected mass-dependence effects are large but the underlying backgrounds are also high. Key to identifying such jets is the 3-layer Monolithic-Active-Pixel-Sensor(MAPS) based vertex detector, originally developed...
Event shape observables, such as transverse sphericity $S_{\perp}$, have long been proposed to study geometrical properties and patterns of the energy flow, and provide a probe of multi-jet topologies in an interaction. For example, the event is pencile-like when transverse sphericity $S_{\perp}\rightarrow 0$, whereas the event is sphere-like when $S_{\perp}\rightarrow 1$. It is well-known...
We will present the first study in full QCD on meson temporal correlation functions in the presence of external magnetic fields at zero temperature. The simulations of (2+1)-flavor QCD were performed on 32$^3$x96 lattices using the Highly Improved Staggered Quarks (HISQ) action with $m_{\pi}$ around 230 MeV. The strength of magnetic fields is up to 3 GeV$^2$.
We found that the masses of...
The Compressed Baryonic Matter (CBM) experiment is one of the scientific pillars of the Facility
for Anti-proton and Ion Research (FAIR), which is presently under construction adjacent to GSI,
Darmstadt. The Silicon Tracking System (STS) is the core detector of the CBM experiment, located
inside the superconducting dipole magnet. The main task of STS is to reconstruct the tracks...
The NICA heavy-ion program is aimed in studying the properties of nuclear matter under extreme conditions. A detailed energy and system size scan will be performed in the center-of-mass energy range from 4 to 11 GeV with an emphasis on the study of yields, spectra, azimuthal anisotropy, fluctuations and correlations of multiple probes from electrons and gammas to light (hyper)nuclei.In order...
Genuine multiparticle azimuthal correlations have been used in anisotropic flow analyses to study the properties of the Quark-Gluon Plasma (QGP) produced in ultrarelativistic nuclear collisions. A recently introduced set of observables, based on the measurements of the correlated fluctuations of two different flow harmonics, has allowed the application of new constraints on the properties of...
Instead of using the generating function or Q-cumulant methods for multiparticle correlation studies in heavy ion collisions, we calculate the cumulants directly looping over particle azimuthal angles. It is shown that this method is not possible for central and mid-central AA collisions due to the required computing resource, but possible for smaller collision systems and peripheral AA...
Jets are collimated bunches of hadrons produced from fragmentation and hadronization of hard scattered partons (quarks and gluons) in high energy collisions. Due to the different color charges of quarks and gluons, differences in the fragmentation of the two types of partons are expected. Therefore jets originated from primary quarks and gluons, are predicted to have different properties....
Recent PHENIX measurements indicate that the initial geometry is the cause of the observed positive $v_2$ and $v_3$ in high-multiplicity p+Au, d+Au, and $^3$He+Au collisions at $\sqrt{s_{\rm NN}} = 200$~GeV. These results were obtained using the event-plane method, with the event plane determined in the backward rapidity range and correlated with particles in other sub-events at mid- and...
A jet is a spray of collimated hadrons originated in the fragmentation of an energetic parton. The cross section measurement provides a good test for pQCD calculations. Jet $p_{\rm T}$ spectrum measurement in pp collisions sets a reference for jet quenching study in nucleus-nucleus collisions. In addition, high multiplicity pp collisions show similar collective behavior as found in heavy-ion...
The non-extensive statistical description of the identified final state particles measured in high energy collisions is well-known by it's wide range of applicability. However, there are many open questions that need to be answered, including but not limited to the question of the observed mass scaling of massive hadrons or the size and multiplicity dependence of the model parameters. This...
High-multiplicity pp collisions show similar collective behavior as found in heavy-ion collisions with comparable event multiplicity, such as long-range near-side correlations and the $v_n$ coefficients. In pp collisions, these effects may be caused by multiple-parton interactions or other vacuum QCD effects. Investigating the modification of the jet shape in terms of the event multiplicity...
For Runs 3 and 4, an ambitious upgrade program is ongoing within the ALICE experiment to further explore the properties of the Quark Gluon Plasma.The Muon Forward Tracker(MFT), one of the major ALICE upgrades, aims to add vertexing capability for muon detection at forward rapidity by providing vital track information in front of the absorber of the Muon Spectrometer. MFT will allow to separate...
Net-charge fluctuations in ultrarelativistic heavy-ion collisions are studied, in terms of the variable $\nu_{[+-,dyn]}$, analysing data from pp, p-Pb and Pb-Pb collisions at $\sqrt{s}_{NN}$ = 5.02 TeV and Xe-Xe collisions at $\sqrt{s}_{NN}$ = 5.44 TeV from the ALICE experiment at LHC. Data from various collision systems provide an opportunity to study the dependence of $\nu_{[+-,dyn]}$ on the...
One of the fundamental goals of heavy-ion collision experiment is to map out the temperature $(T_{f})$ and baryon chemical potential $(\mu_{B}^f)$ of the Quantum Chromodynamics (QCD) phase diagram at which chemical freeze-out occurs - a point on the phase diagram when the chemical composition of the system is fixed. The cumulants of conserved quantities (net-charge, net-baryon number,...
We calculate the first four cumulants of the net-proton number distribution in partial chemical equilibrium (PCE). Such results serve as a necessary baseline for the identification of any critical phenomena in the collision energy dependence of the cumulants. The PCE scenario is relevant for scenarios of the nuclear collisions where chemical freeze-out coincides with hadronisation, but the...
The Solenoidal Tracker at RHIC (STAR) enables the possibility of exploring the properties of strongly interacting nuclear matter using the method of femtoscopy. By studying the quantum statistical effects and final state interactions between two particles, one can extract emission source parameters, which is used to describe geometrical and dynamical properties of the homogeneity region. We...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will enable a spectrum of new or improved cold QCD measurements, enhancing our understanding of the initial state for nuclear collisions. With its excellent tracking and full calorimetry (hadronic and electromagnetic) in the central pseudo-rapidity region, sPHENIX provides excellent opportunities for the studies of the...
Correlation femtoscopy is a standard technique for the experimental analysis of ultrarelativistic nuclear collisions. The measured two-particle correlation function is clearly non-Gaussian, and so it is often better reproduced by Levy stable distribution than a Gaussian one. It has been suggested that a particular shape of a Levy-stable distribution may help to identify the QCD critical...
Heavy-flavor quarks (charm and beauty) play an important role in probing the Quark-Gluon Plasma (QGP) formed in the heavy-ion collisions. Due to their heavy masses, charm and beauty quarks are formed in hard scattering processes on a timescale shorter than the QGP formation time. Therefore, they experience all the phases of the medium evolution interacting with the medium constituents and...
In this talk we investigate the response of the medium of chiral fermions to time and space dependent external electromagnetic fields and chiral imbalance. The axial-vector--vector--vector (AVV) three-point function is studied in a real-time approach at finite temperature in the linear response approximation.
The different orders of limits lead to different results as the external fields...
in this talk there will be discussed the phase structure of the dense quark matter with isospin and chiral imbalances has been investigated in the framework of effective models and lattice QCD. It has been shown that in the large-N$_c$ limit (N$_c$ is the number of colours of quarks) there exist duality correspondences, which are the symmetries of the thermodynamic potential and the phase...
Transverse Single Spin Asymmetries (TSSAs) manifest themselves through
an azimuthal-angle dependence of particle production relative to the
transverse spin direction of the polarized proton in the reaction
p↑ + p → h + X. In recent years, attention has been given to the interplay
with small-x physics by studying TSSAs in transversely-polarized proton-ion
collisions (p↑+A). Recent...
High-transverse-momentum prompt photons, as colorless objects, do not interact strongly with the medium and provide a direct way to test pQCD and the nuclear PDF. The transverse energy spectra and the nuclear modification factors of isolated photons are measured in pp and PbPb collisions at 5.02 TeV using the CMS detector. The data are compared to JETPHOX NLO calculations and found to be...
With our coupled jet-fluid model, we study the nuclear modifications of full jets and jet structures for single inclusive jets and $\gamma$-jets in Pb+Pb collisions at $5.02$ ATeV and $2.76$ ATeV. The in-medium evolution of full jet shower is described by a set of coupled transport equations including the effects of collisional energy loss, transverse momentum broadening and medium-induced...
We investigate whether the QCD crossover gets stronger as the chemical potential is increased. To this end, we study the chiral condensate and susceptibility in a finite volume scaling study at zero and small chemical potentials. We achieve this by extrapolating these quantities from imaginary $\mu_B$ maintaining strangeness neutrality. We also extrapolate low order fluctuations of conserved...
In 2018, LHCb recorded ~210 microbarn$^{-1}$ integrated luminosity of PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. In this talk, we present the first LHCb measurements of open heavy-flavour and J/$\psi$ productions from this new sample. The momentum resolution of the detector allows to probe the boundary of peripheral and ultra-peripheral collisions by comparing hadro-produced and...
The positive elliptic flow ($v_{2}$) of open heavy-flavour particles observed in semi-central Pb--Pb collisions at LHC energies indicates that heavy quarks suffered strong interactions in the deconfined QCD medium and participated in the collective motion of the medium. Recent observations in high-multiplicity pp and p--Pb collisions show remarkable similarities with Pb-Pb collisions and...
At low temperature and low density, the chiral symmetry is broken dynamically to form hadronic phase. While, at high temperature and/or high density, this symmetry is restored and consequently the quark gluon plasma (QGP) appears. In the QCD phase diagram with temperature $T$ and baryon chemical potential $\mu_B$, it is established from first-principle calculations that the transition from...
A Time Projection Chamber (TPC) is a good candidate as the main tracking device for many experiments.
A TPC measures space points of charged tracks, which provide momentum resolution and particle identification for a variety of measurements.
In high multiplicity environments a TPC has to cope with the build-up of space charge in the drift volume which is created by two major effects;...
The measurement of direct photons at forward rapidity in high-energy proton-nucleus collisions is a key to investigate the high-density parton distribution functions and to understand the initial state of nuclear collisions. Gluon distributions at very small x (below 10$^{-4}$) may reach saturation of the phase space. The Color Glass Condensate is a theoretical framework that describes the...
sPHENIX is a new heavy ion experiment at RHIC and aims to study the microscopic structure of quark-gluon plasma by measuring the Jet modification with different flavors and the possible different suppressions of Upsilons.
Intermediate silicon strip tracker (INTT) is one of the tracking detectors sandwiched between the inner silicon pixel tracker (MVTX) and the outer TPC. INTT consists of two...
Heavy-ion collisions at NICA are well suitable to investigate fundamental problem of strongly interacting matter such as its EOS, bulk properties, state of QCD vacuum, and criticality.
The production of (anti)hyperons is sensitive to the early stage of the collision, thus the degree of partonic collectivity can be tested by means of multi-strange baryon yields, spectra, and anisotropic...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will begin taking data in 2023, providing detailed measurements of jets and Upsilons in 200 GeV Au+Au collisions. To make precision jet energy measurements, sPHENIX will be equipped with a Hadronic Calorimeter (HCal) located outside a 1.4T superconducting solenoidal magnet. The HCal is composed of 7,680 plastic scintillating...
The equation of state of dense nuclear matter, while central in simulations of QCD systems under extreme conditions, is currently inaccessible to first principles calculations. Using relativistic density functional theory, we model the thermodynamics and single-particle equations of motion of nuclear matter over a broad range of temperatures and densities encompassing nuclei, neutron stars,...
The study of energy loss of quarks in the hot and dense medium has been performed for decades. Both the experimental and theoretical efforts hinted that the energy loss is quark mass dependent (the yield of heavier quarks will be less suppressed). It was found that the electrons from heavy quarks (charm, and bottom) are less or similarly suppressed compared to that of light hadrons. However,...
A better understanding of parton dynamics in the nucleus, in particular in the small-x region, is extremely important as it is needed to understand the nature of recently observed and unexpected phenomena like particle anisotropies in small collision systems. PHENIX can explore the small and large-x regions in the nucleus through measurements in the muon arms and forward vertex trackers. These...
One of the big puzzles in quarkonia production is how heavy-quark pairs, produced in the initial hard process, hadronize into final quarkonia states. This uncertainty affects the estimation of quarkonia breakup cross sections and color screening in heavy ion collisions. According to Non-Relativistic Quantum Chromodynamics, quarkonia are formed from several intermediate singlet and color octet...
Recently, there have been significant experimental progresses in observing and/or controlling spin-dependent bulk quantities in broad areas in physics, e.g., relativistic heavy-ion collisions, spintronics. Although hydrodynamics is one of the most powerful theoretical frameworks to describe bulk quantities, its extension to a spinful fluid has not been developed well, especially for...
Photon identification in the ALICE EMCal using a neural network and template fit
Alwina Liu for the ALICE collaboration
The measurement of isolated photon-tagged correlations of jets and jet fragments is a promising channel for the study of partonic energy loss in heavy-ion collisions. Isolated photons are an excellent probe because they constrain the parton kinematics of the initial hard...
Jet modification is now understood to be a multistage effect: a parton produced in a high virtuality initial state, radiates a multitude of partons, giving way to a variety of lower virtuality stages. In the lower virtuality stage, higher energy partons are weakly coupled with the medium and continue to scatter and radiate whereas lower energy partons are strongly coupled with the medium and...
The Compressed Baryonic Matter experiment (CBM) at FAIR aims to study the area of the QCD phase diagram at high net baryon densities and moderate temperatures using collisions of heavy ions at center-of-mass energies of a few GeV per nucleon. Anisotropic transverse flow is among the key observables to study the properties of matter created in such collisions.
The CBM performance for...
In ultra-relativistic nucleus-nucleus collisions a new state of matter where quarks and gluons are not confined into hadrons, the Quark-Gloun Plasma (QGP), is created. The ALICE experiment at the LHC is dedicated to the study of the properties of the QGP. In addition, proton-proton collisions are used as the high energy QCD reference while the study of proton-nucleus collisions provides a...
We study the contribution to the polarization of $\Lambda$ hyperons in relativistic nuclear collisions at high energy from the decays of $\Sigma^*(1385)$ and $\Sigma^0$, which are the predominant sources of $\Lambda$ production besides the primary component, as a function of the $\Lambda$ momentum. Particularly, we determine the longitudinal component of the mean spin vector as a function of...
We study the evolution of jetty and underlying parts of the transverse momentum spectra as a function of multiplicity in pp 13 TeV collisions at midrapidity (|eta|<0.8) using pythia8 event generator. We observe that beyond a multiplicity of dN/deta ~ 40 the maximum reachable leading transverse momentum gets smaller and at the same time the slope of the spectra both in the jetty and underlying...
The system created in high-energy heavy-ion collisions quickly reaches local equilibrium and its evolution is usually modeled with relativistic hydrodynamics. However, the effects of the early, pre-equilibrium stages of system evolution on final-state observables are largely unknown. In this work, we study the effects of pre-hydrodynamic evolution on final-state observables in various...
The Joint Zero Degree Calorimeter Project, JZCap, seeks to deploy new high resolution ZDCs for ATLAS, CMS and possibly other experiments for Run 3 of the LHC. These ZDCs will be radiation hard enough to measure forward neutrons and bremsstrahlung photons during PbPb, pPb and dedicated pp running. The ZDCs are tungsten Cerenkov calorimeters where the active medium consists of fused silica...
We present the first public release of the HIJING++ Monte Carlo event generator for high energy heavy ion collisions. Along with the summary plots and experimental validity checks the download and technical instructions will be presented for the first time. The code is developed in modern C++ and is a complete revision of the original FORTRAN HIJING [1,2]. The state-of-the-art framework...
In this talk a pair of observables are proposed as alternative ways to study the charge separation induced by Chiral Magnetic Effect (CME) in relativistic heavy ion collisions. They are, the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pairs rest frame, and the ratio of it to similar measurement made in the laboratory frame. Both...
Gluon nuclear PDFs still have large uncertainties in the small-x ($x$<10^{-3}) and small virtuality $Q^2<$50 (GeV/c)$^{2}$ region. Yields from particles coming from these gluons obtained in nuclear collisions are suppressed relative to $p$+$p$ collisions because of initial-state effects such as shadowing, energy loss and gluon saturation. Precise measurement of yields coming from small-x,...
Charm quarks are excellent probes to study properties of the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. In particular, measurements of the $D_{s}^{\pm}$ meson production can provide valuable information on the strangeness enhancement in the QGP as well as the charm quark hadronization mechanisms in heavy-ion collisions. In this poster, we will present results...
The production of quarkonia in hadron-hadron collisions occurs at the transition between the perturbative and nonperturbative regimes of QCD, resulting in a rich phenomenology that remains far from being fully understood. $J/\psi$ hadronization dynamics can be studied by measuring the $p_{T}$ fraction, $z \equiv p_{T,J/\psi} / p_{T,jet}$, carried by the $J/\psi$ meson detected inside a jet....
Charm quarks are an ideal probe of the QGP created in heavy-ion collisions as they are produced at very early stages of such collisions and subsequently experience the whole evolution of the system. At STAR experiment, charm quark production can be accessed by direct topological reconstruction of open-charm hadrons thanks to an exceptional spatial resolution of the Heavy-Flavor Tracker...
Various recent measurements of high-multiplicity pp and p-A collisions at the LHC center-of-mass energies have revealed, surprisingly, that these small collision systems exhibit some of the quark-gluon plasma features, e.g. collective behaviour and strangeness enhancement, formerly thought to be achievable only in heavy-ion collisions. A promising method to narrow down the origin of this...
Measurements of the production cross sections of heavy quarkonia, namely J/$\psi$ and $\psi$(2S), in hadron-hadron collisions provide valuable information about yet unsolved questions of Quantum Chromodynamics. The Solenoid Tracker At RHIC (STAR) is a major high-energy nuclear physics experiment at the Relativistic Heavy Ion Collider. Its Muon Telescope Detector, which provides trigger and...
At the end of 2016 the ALICE experiment at the LHC collected data from p--Pb collisions at $\mathrm{\sqrt{s_{NN}}}$=8.16 TeV.
These data represent an important chance to test the emergence of possible initial state effects, by comparing the transverse momentum distributions of identified light hadrons extracted in this dataset to those previously measured in pp and Pb--Pb collisions, in a ...
Short lived hadronic resonances are very useful tools to probe the evolution of high energy heavy-ion collisions. Owing to the short lifetime of resonances $(\sim 10^{-23}$s), their characteristic properties such as mass, width and yield are very sensitive to the collision dynamics and in-medium effects. Multiple resonances have been studied in ALICE, including $\rho(770)$, $K^{*}(892)$,...
Recent measurements of charm baryon production in pp and p-Pb collisions at LHC energies show a baryon-over-meson ratio significantly higher than expectations from Monte Carlo generators tuned to reproduce the lower values measured in ${\rm e}^{+}{\rm e}^{-}$ and ${\rm e}^{\pm}{\rm p}$ collisions. In Pb--Pb collisions at LHC and Au--Au collisions at RHIC, even higher values of $\Lambda_{\rm...
The first RHIC Beam Energy Scan (BES-I) was run from 2010-2014 to search for the turn-off of signatures of the quark-gluon plasma (QGP), evidence of the first-order phase transition, and the possible QCD critical point. The QGP signatures studied in BES-I became insensitive or disappeared at energies below $\sqrt{s_{NN}}$ = 19.6 GeV. The fluctuations in the event-by-event net-proton...
Heavy quarks are ideal probes of the QGP matter. To consistently describe the medium evolution and heavy-quark-medium interaction, we improve the linear Boltzmann Transport (LBT) model [Phys. Lett. B777 (2018) 255-259] by modeling QGP as a collection of quasi-particles with equation of state (EOS) fitted to the lattice QCD data. We call this QLBT model, in which the in-medium scatterings of...
\documentclass{article}
\usepackage[utf8]{inputenc}
\title{Quantitative evaluation of muon track matching efficiency with Muon Forward Tracker and Muon Spectrometer at ALICE}
\author{Kaede Kamano for the ALICE collaboration}
\date{June 2019}
\begin{document}
\maketitle
ALICE has been designed to study the quark-gluon plasma in heavy-ion collisions at LHC. Extensive efforts in...
In heavy ion collisions, physical properties of quark-gluon plasma(QGP) have been long studied. In these experiments, survival probability of quarkonia, which are bound states of the heavy quark and antiquark pair, is expected to be a good probe to the formation of the QGP. Their dynamics has been studied to interpret the experimental data.
A quarkonium can be theoretically described by...
Many-body systems with chiral fermions exhibit anomalous transport phenomena originated from quantum anomalies. Based on quantum field theory, we derive the quantum kinetic theory for Dirac fermions interacting with an external electromagnetic field in a background curved geometry. The resultant framework is U(1) gauge invariant and local Lorentz and diffeomorphism covariant. In this talk, I...
Quark-hadron continuity [1] is a scenario that the hadronic matter is continuously connected to a color superconducting phase without phase transitions as the baryon chemical potential increases. This scenario is based on the fact that the two phases have the same symmetry breaking pattern, in the spirit of Landau's classification of phases. When we consider quantum phases of matter, it is...
Quarkonia suppression has been long predicted \cite{satz19861} and explored as a defining signature of formation of quark-gluon-plasma (QGP). Various physical processes \cite{satz19861,laine20071,brambilla20081} have been understood to contribute to the dynamics of a Q-$\bar{Q}$ traversing through the QGP. The proper framework to implement a Schr\"{o}dinger equation, which takes into account...
In heavy ion collision experiments at RHIC and LHC, quarkonium yields have been measured at various collision energies. The experimental findings reveal different characteristic behavior: sequential suppression dominates for bottomonium and recombination for charmonium. A comprehensive understanding of this phenomenology requires a genuine quantum mechanical treatment, in particular to capture...
One of the major physics goals of the sPHENIX experiment at RHIC
is to major the Upsilon states with 100MeV mass resolution. In order to
achieve this resolution, a Time Projection Chamber (TPC) was proposed
for momentum measurements of electrons and hadrons. The TPC does
not have a gating grid similarly to the ALICE TPC case and therefore
capable for handing the collision rate of up to a...
Hadronic resonances are unique and useful probes of ion-ion collision systems. They can be used to study the evolution of the hadrochemistry with system size, including resonance suppression and strangeness enhancement. Resonances can also be used to explore the various mechanisms that influence the shapes of hadron $p_{\mathrm{T}}$ spectra and to search for the possible onset of collective...
The Compressed Baryonic Matter experiment (CBM) and the High Acceptance Di-Electron Spectrometer (HADES) are part of a worldwide research program devoted to study the phase diagram of strongly interacting matter at high baryon densities $\rho_{B}$ and moderate temperatures $T$ in p+A and A+A collisions. One of the major observables addressed by both experiments is dilepton production.
A...
Using a transport model based on BAMPS, we investigate the evolution of magnetic field in a system of charged particles, which is embedded in a cylinder with the periodic boundary condition. We find that when the ratio of the helicity to the magnetic energy goes to a maximum, the system relaxes towards the CKW state with ∇×B∥B and we test the result both in classical plasma and QGP.
Within proton-lead collisions collected by the LHCb detector at nucleon-nucleon center-of-mass energy of 5 and 8.16 TeV, a rich set of open charm hadrons is observed with abundant statistics. Thanks to the LHCb forward acceptance that is complementary to general purpose detectors and excellent performance in particle reconstruction and identification, these charm states are studied down to...
We mainly focus on the effect of rotation on the QCD phase structure in a background magnetic field. We analyze the energy spectra of Dirac fermions in the presence of rotation and magnetic field. We find that the Landau degeneracy is resolved by rotation. A drastic change in the energy dispersion relation leads to the “rotational magnetic inhibition” that is a novel phenomenon analogous to...
We study the promising perspective of search for axion-like particles (ALP) at the future electron-ion collider experiments. ALP could be the candidate for the dark matter of the universe. We calculate the production rate for those ALPs which are coupled to photons at electron-ion collider. Because of the large gamma factor for the electron but more prominently due to the achievable high...
The QCD critical point can attract the system evolution trajectory in the QCD phase diagram, which is recognized as the QCP focusing effect[1,2]. To quantify this effect, we employ thermal model and hadronic transport model to simulate the dynamical particle emission along a hypothetical focusing trajectory near the critical point. It is found that the focusing effect can lead to anomalous...
The measurement of reconstructed jets over a wide range in jet energy and jet resolution parameter $R$ is required for comprehensive understanding of jet quenching in heavy-ion collisions. Such measurements are challenging, however, due to the presence of complex, uncorrelated background to the jet signal, and the need to minimize biases in the selected jet population imposed by background...
The chiral magnetic effect is a good observable to investigate the topological and electromagnetic properties of the QGP. But the $\gamma$ correlator, a common observable used to detect the CME, contains both contribution from the CME and its background. This observable can not identify the CME from its background. Recently, a new observable of $R_{\Psi_{m}}$ has been proposed[1-4], which is...
In non-central nucleus-nucleus collisions, an ultra-intense magnetic field reaching 10^15 [Tesla] is generated. Many interesting phenomena such as non-linear QED and Chiral Magnetic Effect are expected to be induced under the field. Nucleus-nucleus collisions are the only one way to generate such a field and to study the field-induced phenomena experimentally.
Di-leptons from virtual photons...
Current measurements of the modification of jets in the quark–gluon plasma necessarily average over the quark–gluon composition of the jets in the sample. This introduces substantial complications in measuring differences of energy loss and modification between quark-initiated and gluon-initiated jets. Additionally, even in the absence of jet modification, a modified quark–gluon fraction of...
We calculate the shear viscosity of ultrarelativistic Boson systems in the presence of Bose-Einstein condensate (BEC). Two different methods are used. One is the Grad’s method of moments and another is the Green-Kubo relation within a kinetic transport approach. In this work we consider a Boson system with isotropic elastic collisions and a gluon system with elastic scatterings described by...
Photons and dileptons offer themselves as 'clean' probes of the quark-gluon plasma because they are unlikely to reinteract once produced. Their emission rates are given via the vector spectral function $\rho_{\mu\nu}$, an object that can ultimately be reconstructed by analytic continuation of lattice data. To help scrutinise ensuing systematic uncertainties, we determine the NLO corrections to...
Chiral Magnetic Effect (CME) is the macroscopic manifestation of the fundamental chiral anomaly, and emerges as an anomalous transport current in a many-body system of chiral fermions such as the hot quark-gluon plasma created in heavy ion collisions. Experimental observation of CME would provide a tantalizing evidence for the chiral symmetry restoration as well as QCD topological...
We have investigated the chiral anomalies with transport simulations in a box system. In the box system with the periodic boundary condition under a uniform magnetic field, the chiral magnetic effect and the chiral magnetic wave were simulated based on the spin kinetic equations of motion (SEOM) and the chiral kinetic equations of motion (CEOM), with the latter derived from the SEOM for...
The Compressed Baryonic Matter (CBM) experiment will access a wide range of physics observables for heavy-ion collisions in the region of highest net-baryon densities. One of the core topics of its physics program are the measurement of rare thermal dilepton channels. These EM probes have a very low cross section and therefore need very high statistics and a powerful particle identification....
The electromagnetic (EMCal) and hadronic (HCal) calorimeters for the sPHENIX
experiment will use about 100,000 silicon photomultipliers (SiPMs) as optical sensors (Hamamatsu S12572-33-015P). The effects of radiation damage in SiPMs from gamma rays has been measured and compared with the damage produced by neutrons. We have designed and constructed an automated SiPM testing device that...
Over the past years, the observed features in the collisions of small systems which resemble collective flow patterns, are under intense debates. A relevant question is to what extent these observations are related to the real collective evolution of the medium, and if this is the case, the related question is what is the smallest system size which can still accommodate collective behaviour....
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) benefits from the extensive detector advances driven by LHC and Electron-Ion Collider (EIC) detector R&D. The combination of electromagnetic calorimetry, hadronic calorimetry, precision tracking, and the ability to record data at a very high rates enables measurements of jets, jet substructure, and jet
correlations at RHIC...
A strong enhancement of $\Lambda_c$/D$^0$ ratio compared to the fragmentation baseline is observed in Au+Au collisions at the top energy of the RHIC. This also suggests that $\Lambda_c$ may be an important component for the total charm cross section. Precision measurements of charm baryons over a broad momentum range are needed for a detailed understanding of hadronization and parton energy...
Abstract: The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) is designed to accurately study proton-proton, proton-nucleus, and nucleus-nucleus collision systems. The design of sPHENIX, including full azimuthal calorimeter coverage, will allow it to precisely study properties of the Quark Gluon Plasma through open heavy flavor production, jet modification, and Upsilon...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will probe the strongly interacting Quark-Gluon Plasma (QGP) with jets, heavy flavor tagged jets and Upsilon production. The sPHENIX electromagnetic calorimeter (EMCal) detector is essential for these measurements. The Chinese sPHENIX EMCal Consortium includes groups from Fudan, PKU and CIAE, and the consortium is planning to...
The sPHENIX MVTX detector will be a state-of-the-art monolithic active pixel (MAPS) vertex detector, used by the sPHENIX collaboration, which will allow the study of heavy flavor physics within heavy ion collisions at RHIC. The detector is at an advanced stage of testing with several test beam activities having taken place through 2019. Three test beams have been performed since 2018 to...
In this contribution we investigate the properties of the complete Israel-Stewart equations when perturbed around a global equilibrium state. Such analyses have been previously performed including only the effects of the shear-stress tensor and/or bulk viscous pressure and only using the simplified Israel-Stewart equations (which do not include any second order terms, except the one related to...
Measurement of pseudorapidity dependence of local event plane correlations may reveal the possible existence of twist in participant matter density distribution, which provides a novel input in initial conditions of heavy-ion collisions. The factorization ratio, $r_2(\eta)=\frac{\langle V_2(-\eta,\eta^{ref}) \rangle }{ \langle V_2(\eta,\eta^{ref})\rangle }$, has been extensively used to...
The observability of the Chiral Magnetic Effect in heavy-ion collisions has been argued to strongly depend on collision energy because of the variations in the lifetime of magnetic field, the domain size of chiral charge and also on the possibility of formation of a medium with deconfinement and chiral symmetry restoration. While isobar analysis at top RHIC energy is ongoing, in this poster...
The Compressed Baryonic Matter (CBM) experiment aims at exploring the QCD phase diagram at large baryon densities with heavy ion beams in the beam energy range from 2 A GeV to 11 A GeV at the SIS100 accelerator of FAIR/GSI. For charged particle identification that is required by many observables that are sensitive to the phase structure like collective flow, phase space population of rare...
Strangeness production is a classic tool to study properties of the quark gluon plasma (QGP). The ratios of particle yields involving strange particles are often utilized to study various properties of nuclear matter, such as the strangeness chemical potential and the chemical freeze-out temperature. In particular, the yield ratios $(N_{K}N_{\Xi})/(N_{\phi}N_{\Lambda})$ and...
The BM@N (Baryonic Matter at Nuclotron) is the first experiment started at the accelerator complex of NICA-Nuclotron. The aim of the BM@N experiment is to study interactions of relativistic heavy ion beams with fixed targets. The scientific program comprises studies of nuclear matter in the intermediate energy range between experiments at the SIS-18 and NICA/FAIR facilities. The BM@N...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will enable a comprehensive measurement of jets in relativistic heavy ion collisions. The detector will cover the full azimuth and a pseudorapidity range of |η| < 1.1. The tracking system will consist of a silicon detector (MVTX) based on MAPS (Monolithic Active Pixel Sensors), followed by an Intermediate Tracker (INTT),...
Measurements of long-range, collective azimuthal correlations involving heavy-flavor quarks provide a powerful tool for unraveling the origin of the collectivity observed in small collision systems. In particular, these measurements are sensitive to the early stages of the collisions. As compared to those for light flavor hadrons, large azimuthal anisotropy signals have been observed by CMS...
Measurements of the jet substructure in Pb+Pb collisions provide information on the jet quenching in the quark-gluon plasma (QGP) created in these collisions, over a wide range of energy scales. This poster presents ATLAS measurement of the suppression of yields of large-radius jets and its dependence on the jet substructure, characterized by the presence of sub-jets and their angular...
We study charge-independent (CI) and charge-dependent (CD) two-particle differential number correlation function, $R_{2}( \Delta\eta, \Delta\varphi)$, and transverse momentum correlation function, $P_{2}( \Delta\eta, \Delta\varphi)$, of unidentified ($h^{\pm}$) and identified (i.e. $\pi^{\pm}, K^{\pm}$ and $p\bar{p}$) charged particles produced in pp collisions at $\sqrt{\textit{s}}$ = 2.76...
${\rm W}^{\pm}$ bosons are created in hard scattering processes at the initial stage of heavy-ion collisions and they are insensitive to the presence of the strongly-interacting medium. This makes them clean probes of the initial-state effects in heavy-ion collisions, such as the nuclear modification of the Parton Distribution Functions (nPDFs). Furthermore, their measurement in heavy-ion...
Recent ALICE results on the yield of strange particles in pp and p-Pb collisions reveal the possibility that similar strange quark production mechanisms could be present in all collision systems. The $p_{\rm T}$-dependent baryon-to-meson yield ratio in hadronic and nuclear collisions is sensitive to the collective expansion of the system, the partonic recombination into hadrons, the jet...
Photons and dileptons ($\gamma^{*} \to l^{+}l^{-}$) are unique tools to study the space-time evolution of the quark-gluon plasma (QGP) produced in high-energy heavy-ion collisions.
The space-time evolution of heavy-ion collisions can be calculated using relativistic hydrodynamics and hadronic transport models.
Up to the present time, theoretical models fail to describe the large direct...
Studies of jet energy loss and momentum broadening with photon-jet momentum and angular correlations will be presented, with PbPb data at 5.02 TeV collected by the CMS detector. Photon-jet events provide a means of probing in-medium jet energy loss with good constraints on the initial parton kinematics and flavour. Studies of momentum and angular correlations in photon-jet events can enable...
Jet quenching is one of the well-established signatures of the quark-gluon plasma produced in heavy ion collisions. Studies of energy balance for back-to-back hard probes, as well as medium-induced modifications to jet shapes and fragmentation functions, provide important experimental constraints for theoretical understanding of QGP properties. Using large sample of dijet events from 5.02 TeV...
The anomalous side-jump mechanism is a Lorentz invariant and angular momentum conserved approach to include the spin-orbital interactions in scatterings of chiral fermions [1]. In the present study, we incorporate for the first time this mechanism in a transport model that is based on the chiral kinetic equations. For a system of rotating and unpolarized quarks in a box, we find that the...
The aim of relativistic heavy-ion collisions is to investigate the properties of the Quark-Gluon Plasma (QGP) created at high-enough temperatures and/or densities. For this purpose, heavy-quarks, i.e. charm and beauty, are very useful probes for the characterization of the QGP. They are produced at the early stages of the collisions via initial hard scatterings and, therefore, they experience...
The study of charged-particle production in small systems as a function of event multiplicity has exhibited many of the features of collective behaviour found in heavy-ion collisions. Event multiplicity dependent studies may be subject to significant autocorrelation bias due to jet production. In order avoid these effects, a new multiplicity estimator has been proposed which is based on the...
Utilizing our developed relativistic viscous hydrodynamic code [1] to analysis of proton-lead and lead-lead collisions at the LHC [2], we investigate applicability of hydrodynamics, QGP bulk property and viscosities effects at hadronization process. Here we focus on one-particle distributions such as rapidity distributions and particle identified transverse momentum spectra and elliptic flows....
One of the remaining puzzles in heavy-ion physics is that strangeness enhancement - believed to be a signature of the Quark-Gluon Plasma - is not only observed in heavy-ion collisions, but also in high-multiplicity proton-proton and proton-nucleus collisions. Various phenomenological models have been developed to try to understand this, such as rope hadronisation (used in the Angantyr...
The behavior of the $\phi$ meson in nuclear matter has attracted renewed interest because of (recent and future) experiments that aim to study its properties in nuclei [1-3]. Theoretically, many works have however been conducted assuming infinite nuclear matter [4-5], which is not realistic from an experimental point of view. To relate theoretical predictions with experimental observables, a...
We study the feasibility of a substructure-based classification of medium-modifed jets employing a metric formulated in terms of the earth mover's distance. We aim at isolating a subset of jets measured in p--Pb or Pb--Pb collisions that is characterized by an enhanced dissimilarity to the vacuum sample. The selected jet ensemble can be then inspected by projecting it on any substructure...
We investigate fluid-to-particle conversion using the usual Cooper-Frye approach but with more general local equilibrium distributions than the Boltzmann or Bose/Fermi distributions typically used. Even though we study ideal fluids (i.e., shear stress and bulk pressure are zero everywhere), we find a suppression of elliptic flow ($v_2$) at high transverse momenta ($p_T>1.5$ GeV/c), relative to...
We study the behaviour of the η′ around above the pseudocritical temperature by use of lattice QCD simulations with two families of dynamical quarks. Due to its anomalous component the η′ carries significant informations on the nature of the phase transition, and the role of the anomaly. We contrast and compare the results for the η′ with the behaviour of chiral observables as well as with...
Multiparticle correlations built from azimuthal angles whose distributions have been parametrized with the Fourier series expansion, depend generically on two distinct degrees of freedom: flow amplitudes $v_n$ and symmetry-planes $\Psi_n$. While analyses techniques for flow amplitudes $v_n$ have advanced over the past years, robust and unbiased techniques for analysing symmetry-planes...
The validity of the Statistical Hadronization Model (SHM) has been successfully tested to adequately reproduce hadronic particle abundances over nine orders of magnitude in high energy collisions of heavy ions. Assuming a thermally equilibrated system, experimental particle yields at RHIC and the LHC serve as an anchor for the determination of common freeze-out parameters in the QCD phase...
We will present a comprehensive study of chemical freeze-out parameters in high energy
collisions[1-3]. The experimental data of light flavor particles are used to obtain the freeze-out parameters using the statistical thermal model. Three different ensembles are used in this study: the grand canonical ensemble, the canonical ensemble with exact strangeness conservation, and the canonical...
The PHENIX experiment recently found a remarkably simple scaling law for the number of photons emitted in relativistic heavy ion collisions. When the direct-photon invariant yields are divided by $(dN_{ch}/d\eta)^{1.25}$, data from large systems falls onto a single curve in the low transverse momentum ("thermal") region. What is remarkable is that this is true if $dN_{ch}/d\eta$ is varied by...
Recent results at LHC and RHIC involving small collision systems have found evidence of collective flow behavior consistent with relativistic hydrodynamic expectations, which suggests the formation of tiny specks of quark-gluon plasma in these reactions. However, questions still remain about the nature of the matter formed in these minute systems. One of the main signatures of the quark-gluon...
The Chiral Magnetic Wave (CMW) was predicted to arise from the interplay of the chiral magnetic effect and the chiral separation effect, which can lead to the formation of electric quadrupole moment in heavy-ion collisions. This electric quadrupole moment can produce charge asymmetry dependence of the elliptic flow ($v_2$) for charged particles: $v_2(\pm) - v_2(\mp) = \mp r_{2} \times A_{\rm...
Specific heat is a thermodynamic quantity that characterizes the equation of state of the system. For a system undergoing phase transition, the specific heat, $C_{V}$, is expected to diverge at the critical point. Temperature fluctuation of the system provides an estimation of $C_{V}$. The specific heat can be extracted from event-by-event temperature fluctuation. Thus the variation of thermal...
A Time Projection Chamber (TPC) will be the central tracking detector in the sPHENIX experiment. Its main task is to provide a high tracking efficiency and excellent momentum resolution for precise upsilon spectroscopy and jet measurements. The TPC will cover the full azimuth and a pseudorapidity range of up to $\pm$ 1.1.
A small scale prototype TPC with a radial extension of 40 cm and a...
The electromagnetic (EMCal) and hadronic (HCal) calorimeters for the sPHENIX experiment will use about 100,000 Silicon Photo-Multipliers (SiPMs) as optical sensors (Hamamatsu S12572-33-015P). The effects of radiation damage in SiPMs from gamma rays has been measured and compared with the damage produced by neutrons. We designed and constructed an automated SiPM testing device that measures the...
The charm quarks are mainly produced by primordial hard scatterings in the early stage of the ultra-relativistic heavy-ion collisions. The produced charm quarks propagate through the dense QGP medium formed in such collisions and lose energy during their entire path of travel. The QGP is a statistical system of dynamic colour charges, it can also be characterised by stochastic...
The large Time Projection Chamber (TPC) is the main tracking and PID
device of the ALICE detector. It is currently being upgraded with a new
readout system, including new GEM-based Readout Chambers and new
front-end electronics. This will enable to operate the TPC in continuous mode,
recording the full minimum-bias interaction rate of 50 kHz in Pb-Pb, as
anticipated at the LHC in Run3...
The azimuthal angular correlation between a heavy-flavor meson ($J/\psi$ and $D^0$) and a light hadron has been measured firstly by the CMS experiment. The elliptic flow of $J/\psi$ from the initial state has been successful described recently. We investigate the angular correlation between a $D^0$ meson and a charged light hadron in the Color Glass Condensate framework. Our results show that...
The High Acceptance Di-Electron Spectrometer (HADES) is measuring properties of baryonic matter at moderate temperatures in A+A collisions at the SIS18 accelerator at GSI, Darmstadt. After a long shutdown of SIS18 to prepare for the future FAIR facility, beamtimes have been resumed within the FAIR Phase-0 program in March 2019.
Meanwhile, the HADES experiment has undergone several upgrades....
Neutral mesons and jets are good probes to study particle production mechanisms and jet phenomena in various collision systems, providing comparisons to model calculations and constraining coefficients of hot QCD matter. Recent measurements of ALICE in pp collisions show a modification of the $\eta/\pi^{0}$ ratio for the neutral meson production in jets with respect to the inclusive...
In order to study the high-density nuclear equation-of-state in collisions between gold nuclei at Nuclotron beam energies (2– 4.5A GeV), the existing BM@N experiment at JINR in Dubna has to be substantially upgraded. The measurement of high-multiplicity events at reaction rates up to 50 kHz requires the installation of four new tracking stations equipped with double-sided micro-strip silicon...
In order to measure the orientation of the spectator reaction plane, the CMS Zero-Degree Calorimeters (ZDCs) are augmented with two 4x4 hodoscopes of quartz tiles, called the Spectator Reaction Plane Detectors. To reduce electronic noise the signals are digitized in the tunnel, very close to the detectors, which sit at zero degrees, 140m from the interaction point. The performance of the...
The MVTX detector will serve as the inner tracker of the sPHENIX experiment at RHIC. It is an extremely precise silicon pixel vertex detector, with excellent displaced secondary vertex detecting capabilities. The MVTX will enable key measurements of heavy-flavor-tagged jets and B-mesons in heavy ion collisions. The detector is based on the latest generation of Monolithic Active Pixel Sensors...
Jets initiated by the fragmentation of heavy flavor quarks (HF-jet) are sensitive to collisional energy loss of the high energy parton when traversing through Quark Gluon Plasma. Using the state-of-the-art jet detector at RHIC, sPHENIX, we will perform the first HF-jet measurement at RHIC, which includes the nuclear modification and flow of b-jets, and the momentum balance in di-b-jet pairs. A...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will study QGP properties with heavy bottom quark jets (B-jets) produced in high-energy heavy ion collisions. B-jets are expected to offer a unique set of observables due to the large bottom quark mass, but need to be measured across an unexplored kinematic regime, particularly at low $p_T$ where the expected mass-dependence...
Recent data from RHIC and LHC show that $\mathrm{R}_\mathrm{AA}$ and $\mathrm{v}_2$ of charm hadrons are very similar to that of light and strangeness hadrons. The $\mathrm{R}_\mathrm{AA}$ of bottom decay daughters at low p$_\mathrm{T}$ seems to be less suppressed than that of light and charm hadrons, suggesting a mass suppression hierarchy. Precision open bottom measurements over a broad...
We present measurements of the second-order off-diagonal cumulants of net-charge, net-proton, and net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}} =$ 7.7-200 GeV. We focus on the pseudorapidity window and centrality dependence of these cumulants. We compare our results with the hadron resonance gas (HRG) and UrQMD calculations. The energy dependence of the second order...
Measurements of the correlated fluctuations of the amplitudes of two different flow harmonics have been shown to be more sensitive to the properties of the Quark-Gluon Plasma created in ultrarelativistic heavy-ion collisions than the flow harmonics taken individually. In particular, their computation have given constraints to the details of the temperature dependence of shear viscosity to...
Classical and quantum Tsallis distributions have been widely used in many branches of natural sciences. But, the quantum field theory of the Tsallis distributions is relatively a less explored arena. In the article arXiv:1906.02893v2 [hep-ph], we derived the expressions for the thermal two-point functions for the Tsallis statistics with the help of the corresponding statistical mechanical...
Sexaquarks are a hypothetical low mass, small radius uuddss dibaryon which has been proposed recently and especially as a candidate for Dark Matter [1]. The low mass region below 2 GeV escapes upper limits set from experiments which have searched for the uuddss dibaryon and did not find it [1].
Depending on its mass, such state may be absolutely stable or almost stable with decay rate of...
Due to the relative motion of the charged heavy-ions in heavy-ion-collision experiments, a high magnetic field is produced. The initial magnitude of this magnetic field can be very high at RHIC and LHC energies at the time of the collision and then it decreases very fast. The presence of an external anisotropic field in the medium subsequently requires modification of the present theoretical...
The recent detection of gravitational wave signal from binary
compact star merger has set a strong constraint on tidal defomability,
which motivated a large amount of studies about the equation of state.
But the tidal deformability of compact star depends not only on the
equation of state, but also on the spin and magnetic field of the star.
In this study, we calculated for the first...
In the past several years there has been increasing interest in the chirality imbalance $n_5$, which is the difference between right- and left-handed fermions. The chirality imbalance is expected to be produced from the Adler-Bell-Jackiw anomaly(ABJ-anomaly) and plays a key role to understand anomalous transport phenomena in the hot/dense quark matter or the Dirac/Weyl semimetals under the...
During the second LHC shutdown (LS2) the Inner Tracking System (ITS) of ALICE will be upgraded by replacing the current ITS with seven layers of CMOS Monolithic Active Pixel Sensors (MAPS). However, the latest innovations in the silicon imaging technology allow for the construction of large, ultra thin silicon wafers which can further improve the capabilities of the ALICE tracker. A proposal...
The origin of long-range collective azimuthal correlations in small-system collisions is an area of intense research in the heavy ion community. To disentangle between collectivity associated with initial-state intrinsic momentum anisotropy and the collectivity arising as a final-state response to the collision geometry, we studied the development of collectivity in 5.02 TeV and 0.2 TeV $p$+Pb...
Complementary to jet reconstruction, two-particle correlations in $\Delta\eta$ and $\Delta\varphi$ are used to study jets, in particular their particle composition. While in Pb-Pb collisions this is done as means for the characterization of the Quark-Glon Plasma, pp collisions serve as reference and also allow for a deeper study of particle production mechanisms. Recent ALICE results on the...
The second phase of the beam energy scan at RHIC is currently ongoing with the goal to identify signals for the first order phase transition or the critical endpoint. One basic observable that needs to be understood before assessing more complex correlations and fluctuations is the rapidity distribution of net protons, that determines the net baryon density of the system.
The stopping...
The LIDO partonic transport model is used to study the evolution of hard partons inside the quark-gluon plasma produced in heavy-ion collisions.
The energy loss model includes scatterings between hard partons and the medium as well as inelastic (bremsstrahlung) processes.
Importantly, the model takes into account the finite formation time of parton bremsstrahlung, an essential ingredient...
We apply the iterative Bayesian unfolding method provided by RooUnfold package in the non-binomial efficiency correction problem for higher moments. We study the non-binomial efficiency distribution such as beta-binomial and hypergeometric distributions in this work. We also consider the efficiency with multiplicity dependence and the effect of track merging, which will lead to non-binomial...
The sPHENIX detector at BNL’s Relativistic Heavy Ion Collider (RHIC) will provide a detailed understanding of the evolution of the Quark-Gluon Plasma using precision measurements of jets and heavy flavors in heavy ion collisions at RHIC. The sPHENIX detector is based on the former BaBar 1.5T super-conducting solenoid and consists of precision tracking, electromagnetic (EMCal) and hadronic...
Comprehensive understanding of medium-induced radiative energy loss is of a paramount importance in describing observed jet quenching in heavy-ion collisions. In this work, we calculate the medium-modified gluon splitting rates for different profiles of the expanding partonic medium, namely profiles for static, exponential, and Bjorken expanding medium. In the presented study, the...
While at at zero baryon chemical potentials one expects a minimum in the shear viscosity over entropy density and a maximum in the bulk viscosity to entropy density ratio, the exact values where these characteristic temperatures occur has not yet been determined from first principle Lattice QCD calculations and may occur anywhere within the cross-over regime of the phase transition. However,...
Heavy-ion collisions produce asymmetric pressure gradients which convert via interactions the initial spatial asymmetry into an anisotropy in final state momentum space, a phenomenon referred to as anisotropic flow. Anisotropic flow is characterized using the harmonic coefficients $v_{\rm n}$ in a Fourier decomposition of the azimuthal distribution of produced particles relative to the...
The recent detection of a binary neutron star merger using gravitational waves and electromagnetic signals marked the dawn of the multi-messenger astronomy era. Such events are expected to provide key information about the properties of matter at extreme densities and temperatures and, for many years, it was assumed that this system could be reasonably described as an ideal (i.e. inviscid)...
It’s believed that the properties of quark-gluon-plasma (QGP) can be studied through measurements of the jet quenching phenomenon. More specifically, observation of jet substructure variables may reveal the microscopic properties of the QGP.
Recently the modification of groomed jet observables was studied in heavy-ion collisions [1]. In addition, the Lund radiation plane was introduced to...
The chiral vortical effect (CVE) is believed to be intrinsically related to the anomalies of the axial current and the topological properties of the system. It was suggested that the CVE can be generalized to systems of higher-spin particles and, particularly, to photons. However, there is no local gauge invariant definition of photonic helicity current. This problem can be overcome with an...
