Opportunities for Exploring Longitudinal Dynamics in Heavy Ion Collisions at RHIC

The last decades of heavy ion collisions have been marked by significant progress in understanding the transverse structure and dynamics in heavy ion collisions. Spurred by the observations of highly distorted correlation structures in heavy ion collisions the community has developed a detailed picture encapsulated in sophisticated dynamical models to capture these details. These models have led to significant improvements in our understanding of the emergent properties of high density, high temperature QCD, including transport properties.

Even with this significant progress however, important open questions remain about the longitudinal structure and dynamics in these collisions:

• What is the structure of the initial state and how does it evolve with rapidity?
• Over what rapidity range does coherence in the initial state persist?
• What mechanism or mechanisms transport baryons toward mid-rapidity?
• How large are hydrodynamic fluctuations and how far do they spread in rapidity space?

While many of the questions are fascinating in their own rights, failure to answer some will make it difficult to draw conclusions about other aspects of Heavy Ion collisions, including the nature of net baryon fluctuations and the extent to which hydrodynamic noise influences the correlation functions used to determine the transport properties of the QGP. In this workshop, we will discuss these open questions and the opportunities that may be available to answer these questions in a physics program that could be conducted during the final phases of RHIC operations.

Last Modified: October 29, 2021