In heavy-ion collisions at relativistic energies, a hot and dense medium called quark-gluon plasma (QGP) is created. Intriguingly, the collective motion of produced particles, which is thought to be a strong evidence of the formation of QGP, is also seen in small systems like pp and p–Pb collisions. Such a study can be done in the ALICE experiment at the LHC via long-range two-particle...
Recently, many results suggesting the production of Quark-Gluon Plasma (QGP) in high multiplicity events in small collision systems have been presented. These results were reported with surprise and have been a topic of intense discussion.
The purpose of the analysis presented in this talk is to look for the possibility of QGP formation in small collision systems through the measurement of...
Jet observables, including jet fragmentation transverse momentum $j_{\rm T}$, parallel momentum $p_{\left|\right|}$, jet fragmentation function $\xi$ and jet constituent transverse momentum $p_{\rm T, track}$ distributions, have been investigated in p $+$ p and p $+$ Pb collisions at $\sqrt{s_{\rm NN}} = 5.02~{\rm TeV}$ via a multiphase transport model (AMPT) [1,2] with new hadronization model...
ALICE is the experiment at the LHC specifically designed to study the properties of the quark-gluon plasma (QGP), a deconfined state of matter created in ultrarelativistic heavy-ion collisions. In this context, light-flavour particle production measurements play a key role, as they can probe statistical hadronization and partonic collectivity. Recent measurements in small colliding systems (pp...
Anisotropic flow is a key probe of the existence of the quark-gluon plasma. Small collision systems, such as proton-proton (pp) and proton-lead (p--Pb), are usually used to provide the reference data for collisions of heavy nuclei. However, inspection of high-multiplicity p--Pb and pp collisions revealed surprising features, usually attributed to collective effects in heavy-ion...
We postulate that non-perturbative QCD evolution of a single parton in the vacuum will develop the long-range QCD collective effects of a multi-parton system, reminiscent of those observed in high-energy hadronic or nuclear interactions with large final-state particle multiplicity final-state particles [1]. Proton-Proton collisions at the Large Hadron Collider showed surprising signatures of a...
There is strong evidence for the formation of small droplets of quark-gluon plasma in $p/d/^{3}$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in $p$+$p$/Pb collisions at the Large Hadron Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proven insightful. In this talk, we present a new...
The thermodynamical properties of the high-temperature and high-density system produced in relativistic heavy-ion collisions can be understood with a systematic study of the produced hadrons' transverse momentum ($p_{\rm T}$ ) spectra. The $p_{\rm T}$ spectra of these hadrons can be described well by a distribution using the Tsallis statistics. The Tsallis parameters $q$ and $T$ measure the...
Jet fragmentation can be studied using the transverse momentum ($j_T$) and longitudinal momentum fraction ($z$) of constituent particles. The $j_T$ distributions of jet fragments have been measured in pp and p—Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV with ALICE, and various parton-shower models reasonably describe the pp results. In this analysis we carry out more detailed measurements of...
Proton-ion collisions at the LHC and RHIC have yielded unexpected trends, notably in measurements of jet nuclear modification factors at different collision centralities. Recent preliminary measurements from STAR in p+Au collisions at $\sqrt{s_{{\rm NN}}}=200$ GeV demonstrate inherent correlations between high-$Q^{2}$ parton scatterings and event activity (EA), measured using either detectors...
Collective flow-like signals including the ridge structure observed in small collision systems at high energies that are similar to those in large collision systems have led to questions about the onset of collectivity in nuclear collisions. Multiparticle cumulant methods are better in extracting the flow signals as they can suppress nonflow effects that are especially significant in small...
Relativistic hydrodynamics has been successful in describing the evolution of Quark-Gluon Plasma, as well as understanding and predicting experimental measurements highlighting the collective behavior of the observed hadrons created in relativistic heavy-ion collisions. In parallel with the remarkable progress made in numerical fluid dynamics, the study of analytical solutions remains helpful...
Direct photons are widely used probe to study the properties and evolution of the hot and dense medium (e.g. QGP) produced in high energy heavy-ion collisions. Being color neutral, they do not interact strongly with the medium and are produced at all stages of the collision.
A universal scaling of the direct photon yield with charged particle multiplicity has been observed for a wide range...
Previous ALICE results indicate a stronger than linear increase of the inclusive normalized J/$\psi$ yield with charged-particle multiplicity, both measured at mid-rapidity, in proton-lead collisions at $\sqrt{s_{NN}}=5.02$ TeV. The corresponding ALICE results on proton-proton collisions at$\sqrt{s}=13$ TeV provide a clearer picture of a stronger than linear increase.
In PYTHIA8, this...
