Relativistic heavy-ion collision experiments aim to study the formation and evolution of a strongly interacting matter, known as Quark Gluon Plasma (QGP). Experiments at RHIC and LHC have shown that a very dense QCD medium is formed in high-energy heavy-ion collisions. The azimuthal anisotropy parameter (vn) has been considered as a good tool for studying the system formed in the early stages of high energy collisions at RHIC and LHC. There are several aspects related to harmonic flow (vn) that supports the existence of QGP phase in heavy-ion collisions. Based on the theoretical study (hydrodynamics and transport theory), it has been observed that a strongly coupled QGP phase is needed to explain experimentally measured vn. We invite overview and original papers with the aim for a systematic study of collectivity in heavy-ion collisions and hence to understand properties and evolution of the Quark Gluon Plasma. Both experimental and theoretical papers are welcome.

Potential topics include, but are not limited to:

• Collective Dynamics:
  • Why is there collectivity and what are the causes? Review of experimental observations and theoretical understanding. Are there any alternative scenarios where the experimental data can be explained without assuming collectivity?
• Flow and Correlations:
  • Elliptic flow: how does the hadronic phase contribute to the flow? How far do we understand the correlation in longitudinal direction? Recent experimental results and theoretical understanding on heavy quarks flow
  • Directed flow: is it connected to a first-order phase transition? What are the roles of produced and transported quarks?
• Collectivity in Small System:
  • Is there any collectivity in small systems (pp, pA, etc.) and how different is it than AA systems? How well are they understood?