Measurements in pp and pโA collisions have revealed that small collision systems exhibit most of the signs traditionally attributed to heavy-ion collisions, such as the smooth increase of the strange hadron yields with the collision multiplicity (strangeness enhancement). A key question is how these effects evolve with system size and whether they can be described within a unified...
The study of high-energy collisions of small systems has generated significant discussions about the initial conditions, including the size of the system, needed to generate the Quark-Gluon Plasma (QGP). Results from asymmetric small systems, such as $p$+Au and $p$+Pb, exhibit some QGP-like signatures (e.g., flow and enhancement of strangeness production) but not others (e.g., jet quenching)....
Measurements of light hadron production provide essential insight into final-state effects in ultrarelativistic nuclear collisions. These effects include collective flow in both small and large systems, hadronization via recombination, strangeness enhancement, and modifications arising from cold nuclear matter. Studies of system-size and centrality dependence further constrain the role of...
The High Acceptance Di-Electron Spectrometer (HADES) [1] installed at the SIS18 accelerator in GSI Darmstadt registers products of heavy-ion collisions (as well as of elementary interactions) at energies of a few GeV per nucleon. The nuclear matter produced in such collisions reaches extreme densities and temperatures [2, 3, 4], comparable to those expected in neutron star mergers [5]....
Strangeness enhancement has emerged as a system-spanning trend in pp, pPb, and PbPb collisions. Whether a similar behavior is present in elementary $e^+e^-$ collisions, where the initial state is clean and final-state interactions are minimal, is a key question for disentangling hadronization dynamics from hot-QCD effects. We present a measurement of the kaon-to-pion yield ratio,...
The LHCb experiment collected large samples of $p$O, OO, and NeNe collisions in the summer of 2025. These samples will allow for precise studies of nucleon structure in light ions in the unexplored low-$x$ region. In addition, these samples will allow for probing the onset of QGP production in light-ion collisions. First results from the light-ion run with the LHCb detector will be presented,...
High-momentum charged particles originate from the fragmentation and hadronization of partons that undergo hard scattering, and their yields are consequently sensitive to parton energy loss in the QGP. The CMS experiment has recently reported a significant suppression of charged-particle production in oxygenโoxygen (OO) collisions at \sqrt{s_{NN}} = 5.36 TeV, providing a first indication of...
Strangeness production has been suggested as a sensitive probe of the early dynamics of the deconfined matter created in heavy-ion collisions. The measurements of the colliding energy dependence of (multi-)strange baryon-to-meson ratios can provide us with insights into the hadronization mechanism, which will contribute to the search for the energy threshold of the production of the Quark...
The new sPHENIX collider detector experiment features a unique tracking system capable of streaming readout, enabling the collection of very large, unbiased p+p datasets previously not available at RHIC. In RHIC Run-24, sPHENIX recorded over 100 billion p+p collisions at 200 GeV in this readout scheme, and is collecting additional p+p data at the end of Run-25 with an even higher fraction of...
The NA61/SHINE experiment at the CERN SPS performs a systematic scan in collision energy and system size to study the onset of deconfinement and the mechanisms of strangeness production in strongly interacting matter. This contribution presents recent results on both charged and neutral hadron production in nucleusโnucleus collisions.
Hadron production results, including the $K^{+}/\pi^{+}$...
The $\Lambda$ binding energy difference between $\rm ^4_{\Lambda}H$ and $\rm ^4_{\Lambda}He$, which is called the charge symmetry breaking in the ground states of a pair of A = 4 hypernuclei, was measured to be $\Delta B_{\Lambda}^4(0_{g.s.}^{+})\approx 350~$keV in nuclear emulsion experiments in the 1970s. In the 2015 and 2016 experiments from J-PARC and A1 collaboration, the binding energy...
Among the various light-flavoured species produced in heavy-ion collisions, light (anti)nuclei present a unique challenge to hadronization models due to their small binding energies compared to the chemical freeze-out temperature of the system. The statistical hadronization model describes their production as part of the same thermal framework that successfully reproduces the yields of all...
Nuclear clusters and hypernuclei serve as essential probes of the strong interaction.
The production of clusters and hypernuclei in heavy-ion collisions is an intricate process that involves the formation of few-body bound systems within a dynamic many-body environment. Accurate knowledge of their static properties is essential input for transport approaches, as it directly determines their...
In relativistic heavy-ion collisions, a large number of light nuclei can be produced. Studying the production mechanism of light nuclei can help us understand the evolution process of relativistic heavy-ion collisions. There have been quite a lot of studies on stable light nuclei, while research on unstable light nuclei is still relatively lacking. Unstable light nuclei are fragile resonance...
At the LHC, matter and antimatter are produced in equal abundance, making it a true antimatter factory. Among the many antiparticles observed, antinuclei are of particular interest, as their production mechanism in high-energy hadronic collisions remains a topic of active discussion and fascination. The ALICE Collaboration has previously measured, for the first time, the production of...
Open heavy-flavor production studies at LHCb provide precise probes of
hadronization in collision systems ranging from $\gamma$Pb interactions to semi-central PbPb collisions. Studies of heavy baryons and mesons containing two different heavy or strange valence quarks probe the interplay of statistical hadronization, coalescence, and multi-parton interactions. From another point of view, the...
Charm and beauty quarks are produced at the earliest stages of ultrarelativistic heavy-ion collisions through hard scattering processes. Quarkonium production serves as a probe of the perturbative aspects of quantum chromodynamics (QCD) through heavy-quark production in the initial hard scattering, while the non-perturbative aspects play a crucial role in the subsequent formation of the heavy...
Heavy quarks are produced predominantly in the initial hard scatterings of high-energy hadronic collisions and therefore provide sensitive probes of heavy-flavor production mechanisms and hadronization in small collision systems. Recent measurements at RHIC and the LHC have shown a strong correlation between heavy-flavor yields and event charged-particle multiplicity in p+p and p+A collisions,...
Quarkonium production in hadronic collisions is a key observable for studying the interaction of heavy quarks with the nuclear medium. While quarkonium states can dissociate and recombine in nucleus-nucleus collisions, their production in smaller systems may be influenced by a combination of initial- and final-state effects such as shadowing and co-mover breakup. Thanks to excellent vertexing...
The production of heavy quarkonium โ bound states of a heavy quark (charm or beauty) and its corresponding antiquark โ is widely used to probe both the properties of quantum chromodynamics (QCD) in high-energy protonโproton (pp) collisions and deconfinement in heavy-ion collisions. In pp collisions, precise measurements of quarkonium production cross sections, polarization, and correlations...
One of the most unanticipated findings of the LHC heavy ion program is the observation of stronger suppressions of the excited $\Upsilon$ states compared to the lower $\Upsilon\mathrm{(1S)}$~state in \mbox{proton-lead} collisions, with the same hierarchy as seen in the larger \mbox{lead-lead}~(PbPb) collision events. Together with other observations of signatures of quark-gluon plasma...
Quarkonia are key probes of the quark-gluon plasma (QGP). Their azimuthal anisotropies, quantified by flow coefficients, provide insight into the collective behavior and degree of thermalization of heavy quarks in the medium. In particular, the elliptic flow $v_2$ of the J/$\psi$ meson in Pb-Pb collisions at the LHC has revealed significant collectivity, supporting scenarios of charm-quark...
Final-state effects such as interactions with co-moving particles or quark coalescence can influence the hadronization dynamics of heavy quarks in nuclear collisions. To investigate these phenomena, we present new multi-differential measurements of the $\Upsilon(nS)/\Upsilon(1S)$ production ratios as functions of rapidity, transverse momentum, and charged-particle multiplicity in proton-lead...
Quarkonium production has long been considered as one of the golden probes to study the quark-gluon plasma (QGP). In fact, the early production of heavy quarks ($c\bar{c}$ and $b\bar{b}$) makes quarkonia an ideal tool to investigate the evolution of the hot and dense medium produced in ultra-relativistic heavy-ion collisions. Moreover, at LHC energies the recombination of uncorrelated charm...
In ultra-peripheral collisions (UPCs), photon-induced production mechanisms include resonant vector-meson photoproduction, the non-resonant Drell-Soding process, and $\gamma \gamma$ processes. Coherent vector meson photoproduction provides a sensitive probe of the gluonic structure of heavy nuclei; vector mesons of different mass (e.g. $\phi$ and J/$\Psi$) offer insights into different...
