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QCD Challenges from pp to A-A Collisions

This paper is a write-up of the ideas that were presented, developed and discussed at the third International Workshop on QCD Challenges from pp to A-A, which took place in August 2019 in Lund, Sweden. The goal of the workshop was to focus on some of …

Dynamics of critical fluctuations: Theory – phenomenology – heavy-ion collisions

This report summarizes the presentations and discussions during the Rapid Reaction Task Force **Dynamics of critical fluctuations: Theory -- phenomenology -- heavy-ion collisions**, which was organized by the ExtreMe Matter Institute EMMI and held at …

Global fluid fits to identified particle transverse momentum spectra from heavy-ion collisions at the Large Hadron Collider

Transverse momentum spectra of identified particles produced in heavy-ion collisions at the Large Hadron Collider are described with relativistic fluid dynamics. We perform a systematic comparison of experimental data for pions, kaons and protons up …

Probing the evolution of heavy-ion collisions using direct photon interferometry

We investigate the measurement of Hanbury Brown-Twiss (HBT) photon correlations as an experimental tool to discriminate different sources of photon enhancement, which are proposed to simultaneously reproduce the direct photon yield and the azimuthal …

Entropy production in pp and Pb-Pb collisions at the LHC

We use experimentally measured identified particle spectra and Hanbury Brown-Twiss radii to determine the entropy per unit rapidity dS/dy produced in $\sqrt{s}=7~\text{TeV}$ pp and $\sqrt{s_{NN}}=2.76~\text{TeV}$ Pb-Pb collisions. We find that …

Hydrodynamic attractors, initial state energy and particle production in relativistic nuclear collisions

We exploit the concept of hydrodynamic attractors to establish a general relation between the initial state energy and the produced particle multiplicities in high-energy nuclear collisions. When combined with an ab initio model of energy deposition, …

Temperature and fluid velocity on the freeze-out surface from $π$, $K$, $p$ spectra in pp, p-Pb and Pb-Pb collisions

We present a new approach to take into account resonance decays in the blast-wave model fits of identified hadron spectra. Thanks to pre-calculated decayed particle spectra, we are able to extract, in a matter of seconds, the multiplicity dependence …

Longitudinal spin polarization in a thermal model

We use a thermal model with single freeze-out to determine longitudinal polarization of $\Lambda$ hyperons emitted from a hot and rotating hadronic medium. We consider the top RHIC energies and use the model parameters determined in the previous …

Chemical equilibration in hadronic collisions

We study chemical equilibration in out-of-equilibrium Quark-Gluon Plasma using the first principle method of QCD effective kinetic theory, accurate at weak coupling. In longitudinally expanding systems---relevant for relativistic nuclear …

Chemical equilibration in weakly coupled QCD

We study thermalization, hydrodynamization, and chemical equilibration in out-of-equilibrium quark-gluon plasma starting from various initial conditions using QCD effective kinetic theory, valid at weak coupling. In nonexpanding systems gauge bosons …