Narrow Results

The color confinement in Quantum Chromodynamics (QCD) remains an interesting and intriguing phenomenon. It is considered as a very important nonperturbative effect to be taken into account in all models intended to describe the QCD many-parton system. During the deconfinement phase transition, the non-Abelian character of the partonic plasma manifests itself in an important manner. A direct consequence of color confinement is that all states of any partonic system must be colorless and the requirement of the colorlessness condition is more than necessary. Indeed, the colorless state is a result of the multiparton interactions, from which collective phenomena can emerge, inducing strong correlations and giving rise to a long-range order of liquid-like phase, a behavior fundamentally different from that of a conformal ideal gas. Within our Colorless QCD MIT-Bag Model and using the ${\mathcal{ℒ}}_{m,n}$-method, three Thermal Response Functions, related to the Equation of State, like pressure $\mathcal{𝒫}(T,V)$, sound velocity ${\mathcal{𝒞}}_s^2(T,V)$ and energy density $𝜖(T,V)$ are calculated and studied as functions of temperature $(T)$ and volume $(V)$. Also and in the same context, two relevant correlation forms $\frac{\mathcal{𝒫}}{𝜖}(𝜖)$ and ${\mathcal{𝒞}}_s^2(𝜖)$ are calculated and studied intensively as functions of $(𝜖)$ at different volumes. A detailed comparative study between our results and those obtained from lattice QCD simulation, hot QCD and other phenomenological models is carried out. We find that the Liquid Partonic Plasma Model is the model which fits our Equation of State very well, in which the Bag constant term is revealed very important. Our Colorless Partonic Plasma, just beyond the finite volume transition point, is found in a state where the different partons interact strongly showing a liquid behavior in agreement with the estimate of the plasma parameter $7.92\le {\mathrm{\Gamma }}_{\mathrm{\text{CPP}}}\le 10.10$ and supporting the result obtained from the fitting work. This allows us to understand experimental observations in Ultra-Relativistic Heavy-Ion Collisions and to interpret lattice QCD results.

The main goal of heavy-ion physics is to study the properties of the deconfined state of matter known as the Quark-Gluon Plasma (QGP) created in ultra-relativistic heavy-ion collisions. A systematic study of strangeness production is of fundamental importance for determining the thermal properties of the system created in such collisions. In the central barrel of the ALICE detector, K${}_s^0$, $\mathrm{\Lambda }$, $\mathrm{\Xi }$ and $\mathrm{\Omega }$ can be identified reconstructing their weak decay topology. It will be shown that the relative production (to pions) of strange particles follows a continuous increasing trend from low multiplicity pp to peripheral Pb–Pb collisions, above which a saturation is visible for central Pb–Pb collisions. This increasing trend is similar for pp and p–Pb collisions. Moreover, comparison of strange particle production in pp collisions at two different energies ($\sqrt{s}$ = 7 TeV and 13 TeV) will be used to demonstrate that the observed trend in multiplicity is also energy independent.