Studies of strong interactions between hadrons provide a unique opportunity to test Quantum Chromodynamics calculations at nucleon-scale distances. The femtoscopy technique, based on measuring correlations of hadron pairs in momentum space, has proven to be a powerful tool to study interactions involving short-lived particles. While strong interactions among light and strange hadrons have been...
Two-particle femtoscopy provides a powerful tool for studying the spatial-temporal characteristics of particle emission source and final-state interactions in high-energy nuclear collisions. The particle emission source size R, and interaction parameters, such as the scattering length $f_0$ and effective range $d_0$, are key to understanding the freeze-out dynamics in such collisions. In...
Femtoscopic techniques provide unique insights into particle production mechanisms in hadron collisions, as well as interactions between short-lived hadrons. The LHCb detector's excellent momentum resolution makes it well-suited for studies of femtoscopic correlations. In addition, LHCb's vertex reconstruction and particle identification capabilities allow for studies of femtoscopic...
Chiral symmetry in QCD is expected to be partially restored at high temperature and/or baryon density, where the chiral condensate that generates most hadron masses decreases. A key manifestation of this restoration is the degeneracy in mass of chiral partners such as vector and axial-vector mesons. To identify these effects, it is essential to achieve a precise understanding of the...
It has been challenging to quantitatively understand the stopping of incoming nucleons in nuclear collisions, and recently it has been proposed that comparing the baryon stopping with electric charge stopping can help address the question. In this study [1] we focus on the B/Q×Z/A ratio, which can strongly depend on rapidity although its value is one for the full phase space. We find that this...
Due to their large masses, heavy quarks (charm and beauty) are predominantly produced in the initial hard-scattering processes. They serve as effective probes of the quark–gluon plasma (QGP) expected to form in heavy-ion collisions, as they traverse and interact with the constituents of the medium throughout its entire evolution. In these collisions, the measurement of the angular correlations...
The Glasma is produced in the pre-equilibrium stage of high-energy heavy-ion collisions within the Color Glass Condensate framework. These strong, classical, out-of-equilibrium gluon fields significantly influence the dynamics of heavy quarks, which are created early in the collision. Our study shows that the azimuthal correlations of $c\overline{c}$ and $b\overline{b}$ pairs are strongly...
The study of charm-quark production and hadronisation provides crucial insights into the mechanisms of Quantum Chromodynamics (QCD) at the interface between the perturbative and non-perturbative regimes. Differential measurements of jets containing charm hadrons further shed light on QCD processes such as parton-shower evolution and hadronisation. In particular, angular correlations between...
This talk presents new ATLAS results that probe the mass and system-size dependence of parton-medium interactions using heavy-flavor jets in Pb+Pb collisions and hard-process correlations in O+O collisions. The first part reports measurements of b-tagged jets and events with multiple jets recoiling against a photon in Pb+Pb collisions. These measurements place strong constraints on the...
Heavy quarks (charm and beauty) are produced in hard partonic scatterings, making their cross sections in proton–proton (pp) collisions calculable in perturbative quantum chromodynamics (pQCD) and thus providing stringent tests of theory. Furthermore, the associated production of two charm hadrons in a single collision probes the dynamics of multiparton interactions, distinguishing between...
Collective behaviors in pp and p–Pb collisions have sparked debate on the onset of hydrodynamics in small systems. However, the proton's poorly constrained geometry has hindered definitive conclusions. The 2025 LHC runs with OO and Ne–Ne collisions provide a unique solution: their well-defined initial states allow a direct test of whether collectivity stems from hydrodynamic flow or...
This presentation reports new ATLAS measurements of soft-particle production and collective flow in light-ion collisions at the LHC. Charged-particle pseudorapidity densities ($dn/d\eta$) and average transverse momenta ($\langle p_T\rangle$) are measured in O+O and Ne+Ne collisions at $\sqrt{s_{NN}} = 5.36$ TeV over the fiducial range $|\eta| < 2.5$ and $0.27 < p_T < 5$ GeV. Fits to the...
Understanding the interaction of strange baryons with nucleons is a key ingredient for describing dense baryonic matter, where the appearance of hyperons in the cores of neutron stars is expected to strongly soften the equation of state, hence limiting the maximum stellar mass. New constraints, not only on two-body but also on multi-body hyperonic interactions, are necessary to address this...
The baryon number transport from beam rapidity to mid-rapidity has been observed from the detection of an excess of hyperons over anti-hyperons numbers around mid-rapidity in nuclear collisions at RHIC energies. To understand the dynamics of the baryon number transport over a large rapidity gap, the gluon junction model, which suggest the Y-shaped gluonic junction in proton and neutron may...
Fluctuations and correlations of conserved charges, such as net-charge (Q), net-baryon (B), and net-strangeness (S), are sensitive to the quantum chromodynamics (QCD) phase transition and the QCD critical point. To achieve this goal, previous studies have focused on the fluctuations of conserved charges, while the correlations of conserved charges also hold significant physical significance....
