Dynamical modeling from small to large colliding systems

In this talk, recent development of dynamical modeling of high-energy nuclear collisions, including large colliding systems such as Pb+Pb as well as small systems such as p+Pb, d+Au, ³He+Au, p+p, etc., will be reviewed. After collective behavior was experimentally found in small colliding systems, dynamical models have been extended to investigate the origin of the collectivity in the small systems. For the large systems, flow fluctuations are measured in detail through event-plane decorrelation, flow correlation, etc. To establish a consistent understanding on collectivity from small to large systems, we need to develop dynamical models that can describe various sizes of systems in a consistent way. The fluctuations in final observables are understood mainly by the initial state fluctuations. While event-by-event distributions of wounded nucleon positions are important in the large systems, fluctuations of proton shape and structure become important in the initial state of the small systems. The effects of longitudinal initial fluctuations to flow decorrelation are investigated as well. Also, in the small systems, non-flow contributions to observables, which are the effects from the non-equilibrated components of the system such as jets, become relatively important since the fluid size and lifetime are smaller compared to the large systems. The core-corona picture can be used to separate the system into the equilibrated matter which is described by hydrodynamics (core), and the other parts described by some microscopic models (corona). Recently several dynamical initial state models are proposed to describe such heterogeneous systems consistently, which are also important in lower energy collisions for high-baryon density. Other sources of flow fluctuations and correlations include hydrodynamic fluctuations, i.e., the thermal fluctuations of hydrodynamics, medium response to jets and mini-jets, etc.