Relativistic Nucleus-Nucleus Collisions and the QCD Matter Phase Diagram

Abstract

This review will be concerned with our knowledge of extended matter under the governance of strong interaction, in short: QCD matter. Strictly speaking, the hadrons are representing the first layer of extended QCD architecture. In fact we encounter the characteristic phenomena of confinement as distances grow to the scale of 1 fm (i.e. hadron size): loss of the chiral symmetry property of the elementary QCD Lagrangian via non-perturbative generation of "massive" quark and gluon condensates, that replace the bare QCD vacuum [1]. However, given such first experiences of transition from short range perturbative QCD phenomena (jet physics etc.), toward extended, non perturbative QCD hadron structure, we shall proceed here to systems with dimensions far exceeding the force range: matter in the interior of heavy nuclei, or in neutron stars, and primordial matter in the cosmological era from electro-weak decoupling (10 −12 s) to hadron formation (0.5•10 −5 s). This primordial matter, prior to hadronization, should be deconfined in its QCD sector, forming a plasma (i.e. color conducting) state of quarks and gluons [2]: the Quark Gluon Plasma (QGP). In order to recreate matter at the corresponding high energy density in the terrestrial laboratory one collides heavy nuclei (also called "heavy ions") at ultrarelativistic energies. Quantum Chromodynamics predicts [2-4] a phase transformation

Estudo de espectros P_T através da decomposição em polinômios ortogonais

“…Particular interesse é dado a transição de matéria confinada para a matéria não confiinada, já que é esse o ponto central para o estudo do diagrama de fase da matéria e as propriedades do QGP por meio da colisão de íons pesados. O estudo dessa transição é um dos principais objetivos experimentos atuais, como RHIC e LHC [8,48].…”

“…Figura 2.3: Diagrama de cone de luz esquemático da evolução de uma colisão de íons pesados de alta energia, indicando uma fase de formação τ 0 [8].…”