Features of the IP-Glasma

TL;DR

This paper compares the IP-Glasma model to traditional models, highlighting its more compact initial state and initial flow, which influence subsequent hydrodynamic evolution and require adjustments like larger bulk viscosity for experimental agreement.

Contribution

It introduces the distinct features of the IP-Glasma initial conditions and their impact on flow and anisotropy in small collision systems.

Findings

IP-Glasma produces a more compact initial state.

Initial flow from IP-Glasma affects radial flow.

Larger bulk viscosity is needed to match experimental data.

Abstract

We discuss differences between the IP-Glasma model and typical wounded-nucleon model like initial conditions. We point out that the IP-Glasma initial state is more compact in the transverse plane and produces a significant initial flow, both of which contribute to an increased radial flow in the subsequent hydrodynamic evolution. A larger bulk viscosity, compared to calculations that use other initial state models, is required to compensate for these effects and find agreement with experimental data. We further demonstrate the importance of the initial momentum anisotropy of the glasma for anisotropy measures in small collision systems such as p+Pb.