This talk presents an overview of recent findings from the ATLAS experiment using heavy-ion collisions. These include measurements of how energetic jets are produced and modified as they travel through the hot, dense medium known as the Quark-Gluon Plasma (QGP), which is created in collisions between atomic nuclei at near light speed. The results also include studies of softer particles...
The fully stripped ions used in heavy-ion collisions at the LHC are an excellent source of high-energy quasi-real photons. These can interact with photons emitted by the oncoming nucleus, or with the nucleus itself, either directly in inelastic processes or diffractively via pomeron exchange. Diffractive photonuclear processes can produce exclusive vector mesons that are uniquely sensitive to...
Since 2009, ALICE has successfully collected data from various collision systems, including A–A (Pb–Pb, Xe–Xe, O–O), p–A (p–Pb, p–O), and pp. This presentation will review recent highlights from ALICE and outline its ambitious short- and long-term upgrade plans.
The measurement of the Drell-Yan (DY) production at forward rapidity in proton-proton (pp) collisions at the LHC with the upgraded ALICE detector in Run 3 provides a unique tool for probing the Parton Density Functions (PDFs) and partonic structure of hadrons and nuclei. There is a lack of a hard and clear probe of nuclear matter at relatively small Bjorken-x (down to 10^–5), which could...
We report the recent results from the HADES experiment obtained in Au+Au and Ag+Ag collisions at center-of-mass energies per nucleon pair of 2.42 and 2.55 GeV, respectively. In particular, measurements of hadronic and dilepton observables are presented, with focus on particle correlations and prospects for the future experimental program are outlined.
The HADES (High-Acceptance Di-Electron Spectrometer) detector is a versatile device operating at SIS18 synchrotron at GSI Darmstadt with a vital list of results in the elementary and heavy ion collisions. It combines unique capability of dileptons and hadrons identification. HADES provides a unique platform for investigating elementary reactions, with a particular focus on the strangeness and...
Heavy-ion collisions at a few AGeV give insight into the intriguing hot and dense region of QCD diagram. In this region, the basic properties of hadrons, like mass or branching ratios may be modified with respect to the values in vacuum.
With rising beam energy, the production of many hadrons increases from rare to abundant. It gives a chance to obtain a multifaceted picture of created...
A thermal model describing hadron production in heavy-ion collisions in the few-GeV energy regime is combined with the idea of nucleon coalescence to make predictions for the $^3$H and $^3$He nuclei production. A realistic parametrization of the freeze-out conditions is used, which reproduces well the spectra of protons and pions. It also correctly predicts the deuteron yield that agrees with...
I will try to review some aspects of the present tecnological developments, like pixel pitch or stitching, from a critical point of view.
The NA61/SHINE experiment at the CERN Super Proton Synchrotron (SPS) investigates the properties of strongly interacting matter by studying hadron production in hadron–hadron, hadron–nucleus, and nucleus–nucleus collisions over a wide range of beam energies. One of the main goals of the program is to measure open charm production, which provides a sensitive probe of the medium produced in...
I will summarise the results presented in two recent papers:
https://inspirehep.net/literature/2655602
https://inspirehep.net/literature/2899809
NA61/SHINE at the CERN SPS is a multipurpose fixed-target experiment designed for measurements of charged and neutral hadrons. The main physics goals of the NA61/SHINE strong interaction program are to study the properties of the onset of deconfinement and to search for signatures of the critical point of strongly interacting matter. These objectives are pursued by performing a comprehensive...
In this talk, I review recent theoretical efforts to understand the excess of charged over neutral kaons measured by the NA61/SHINE collaboration. This excess signals a much larger breaking of isospin symmetry than expected. In particular, the results of hadron resonance gas approach(es) and of the UrQM simulation, as well as considerations involving the electromagnetic interaction and the...
NA61/SHINE is a multipurpose fixed-target experiment located at the CERN SPS. One of its main goals is to study the onset of deconfinement and the properties of strongly interacting matter. For this purpose, a unique two-dimensional scan in collision energy (√sNN = 5.1 − 17.3 GeV) and system size was performed. Results on charged hadron spectra produced in nucleus-nucleus collisions, including...
Measurements of strange hadron production provide information on the properties of strongly interacting matter and on the mechanisms of particle production in high-energy collisions. The NA61/SHINE experiment at the CERN SPS North Area investigates these processes through a two-dimensional scan in collision energy and system size, covering a wide range of hadronic and nuclear interactions.
...
Hyperons are an important probe of strangeness production and the properties of strongly interacting matter in relativistic heavy-ion collisions. While Λ and multi-strange hyperons have been measured extensively, the Σ⁰ hyperon remains much less explored. This is particularly interesting since Σ⁰ shares the same quark content as Λ but carries different isospin, so the Σ⁰/Λ ratio can provide...
There has been a significant debate about the mass of sexaquark, a highly bound compact six quark state which has been hypothesised as a candidate for dark matter. Here we present a simplistic approach motivated by the formalism of Cooper Triples in condensed matter physics to provide a range for the mass which is consistent with the previous bounds. We also discuss the temperature and...
Heavy quarks are produced in hard partonic scatterings at the very early stage of heavy-ion collisions and they experience the whole evolution of the Quark-Gluon Plasma medium. Femtoscopic correlations, i.e. two-particle correlations at low relative momentum, are sensitive to the final-state interactions as well as to the extent of the region from which the correlated particles are emitted. A...
The condition to preserve the internal symmetry of the system leads to new constraints for the kinetic equations.
Abelian symmetries lead to extensive variables that scale proportionally with the system size or number of particles. Nonabelian symmetries lead to variables that do not scale proportionally with the system size or number of particles and are realized by higher factorial...
Fluid-dynamical modeling of heavy-ion collisions at RHIC BES energies is complicated by primary collisions and collective expansion taking place simultaneously. In a multi-fluid model this problem is circumvented by describing the colliding nuclei and produced particles as three separate fluids. I describe the present status of our multi-fluid model MUFFIN (MUlti Fluid simulation of Fast IoN...
The concept of spin hydrodynamics is introduced and the newest developments in this field are reviewed.
We develop a new form of the Wigner function for a relativistic gas of spin-1/2 particles in local equilibrium [1]. This new expression resolves the previously encountered issue with the normalization of the mean spin polarization and also leads to the generalized thermodynamic relations for perfect spin hydrodynamics, agreeing therefore with kinetic theory with classical spin treatment....
We compare two recently developed frameworks of perfect spin hydrodynamics for spin-1/2 particles, based respectively on classical kinetic theory and the Wigner function. We show that the conserved currents in both approaches have the same form at each order of the expansion in the components of the spin polarization tensor ω. The only difference is a relative multiplicative factor, which is...
We analyze the effect of using the Fermi–Dirac statistics, rather than its Boltzmann approxima-
tion, in numerical simulations of perfect spin hydrodynamics of particles with spin 1/2. The system
considered is a one-dimensional boost-invariant expansion with corrections to the energy–momentum
tensor and the baryon current that are second order in the spin polarization tensor ω. The...
At present, our understanding of the non-equilibrium aspects of a relativistic spin fluid is derived from the study of Wigner function coupled with the semiclassical expansion. In our work, we present an exact computation (up to quantum loop corrections) of the Wigner functions for quarks in a field of oscillating pion condensate. The oscillating pion condensate enters the equation of motion...
In this talk I present a Bayesian global analysis of a (2+1)-d viscous hydrodynamics model with event-by-event EKRT initial state describing simultaneously four collision systems: Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV, Pb+Pb collisions at 2.76 TeV and 5.02 TeV, and Xe+Xe collisions at 5.44 TeV. To make the analysis computationally feasible, two layers of model emulation are utilized:...
Lattice QCD results for the magnetic susceptibility of the medium just below the cross-over temperature are difficult to be reproduced by the available hadronic models. In particular, the widely used hadron resonance gas, remarkably successful to describe numerous other lattice results, is substantially too strong diamagnetic as compared to the data, at all temperatures available in the...
In non-central heavy-ion collisions, the presence of strong electromagnetic (EM) fields causes charged hadrons to experience different deflections along and opposite to the impact parameter direction. This results in a splitting of the directed flow between oppositely charged hadrons. Since the strength of the EM field varies with both centrality and system size, studying the directed flow...
We work out the Hopfion description of glueballs by inclusively comparing the energy spectra obtained by quantizing Hopfions with experimental data and lattice QCD. Identifying a Hopfion carrying a unit topological charge as f0(1500), the Hopfions with the topological charge two are classified as glueballonia, i.e., two glueballs are bound together. We find a tightly and a loosely bound...
The Wróblewski factor, proposed 40 years ago [1] and still widely used, is a measure of strangeness production compared to the light quark production. The method is based on the direct comparison of the number of quarks in produced particles. Several assumptions were needed as not all particles have been measured.
Numerous multiplicities of particles (charged and several neutrals) produced...
In the standard picture of heavy-ion collisions, it seems that a large part of the evolution of the produced fireball can be described in terms of classcal theories: relativistic hydrodynaics, the relativistic Boltzmann equation. The quantum effects seem to be restrivcted to the very initial stages, and the computation of some material properties, for instance the transport...
Based on a generalized Beth-Uhlenbeck approach to thermodynamics of QCD motivated by cluster decomposition we present a unified equation of state of hot strongly interacting matter and analyze its properties in a wide range of temperatures. The hadrons are treated as color singlet multiquark clusters in medium with a background gluon field in the Polyakov gauge. The confining aspect of QCD is...
CP violation is known to emerge at finite topological angle, including $\theta=\pi$, which can be related to a negative quark mass parameter. Such a phase with nonstrange and strange eta condensates was indeed identified also in the Columbia plot in the presence of the axial anomaly [2410.08185]. However, anomaly terms corresponding to different topological charge give rise to different...
HADES is an experiment located at the SIS-18 accelerator in GSI, Darmstadt,
Germany. It is a detector setup primarily developed for precise measurements of
dielectrons, but it soon found other uses, including femtoscopy. High angular
acceptance and interaction rates enable the collection of large quantities of
high-quality data, making them useful for any type of analysis. HADES is...
Exploring correlations between photon pairs is a challenging frontier in the field of femtoscopic measurements. Unlike hadrons, direct photons escape the hot and dense medium without final-state interactions, carrying pristine information from the earliest moments of the collision. Therefore, they offer a unique possibility to probe the initial space-time dynamics of the system. Additionally,...
The current theoretical estimations lead to cross-sections for $AA \to \gamma \gamma AA$ which are somewhat smaller than the measured ones by the ATLAS and CMS Collaborations, In our recent paper, we estimated the contribution of inelastic channels to the Light-by-Light (LbL) scattering in ultraperipheral collisions (UPC) of heavy ions, in which one or both of the incident nuclei dissociate ...
