Speaker
Description
The experimental observations of anisotropic flows in proton-proton and
proton-nucleus collisions at RHIC and LHC energies has stimulated a big
interest in these small systems as a new study area for the formation and
evolution of the quark-gluon plasma. We investigate the effects of
non-equilibrium dynamics in such systems by comparing a microscopic
nonequilibrium transport approach, the Parton-Hadron-String-Dynamics
(PHSD), with a macroscopic 2D+1 viscous hydrodynamical model, VISHNew,
that describes a locally approximately equilibrated medium. The initial
conditions for the hydro evolution are taken from PHSD at different
starting times in order to study its impact on the subsequent evolution of
the short-lived QGP created in proton-nucleus collisions, investigated in
terms of energy density, viscous corrections, spatial and momentum
eccentricities. The latters have been linked to the development of
collective flows, whose origin is high-multiplicity proton-nucleus
collisions is still under debate. We address this issue also by means of a
new and more differential observable, the transverse spherocity, which
classifies final-state event topologies and allows to isolate hard and
soft effects. The investigation of such quantity in both transport and
hydro frameworks permits to gain further insights into the mechanisms
responsible for the QGP-like effects in small systems.
