Complex deformations of Bjorken flow

TL;DR

This paper introduces a complex shift of the time coordinate in Bjorken flow, creating a model that transitions between different flow regimes and aligns with experimental data at high energies.

Contribution

It presents a novel modification of Bjorken flow using complex time shifts, providing a unified description of different flow regimes and matching experimental rapidity distributions.

Findings

Interpolates between glasma-like and hydrodynamic regimes

Achieves approximate agreement with BRAHMS data

Provides a closed-form stress tensor expression

Abstract

Through a complex shift of the time coordinate, a modification of Bjorken flow is introduced which interpolates between a glasma-like stress tensor at forward rapidities and Bjorken-like hydrodynamics around mid-rapidity. A Landau-like full-stopping regime is found at early times and rapidities not too large. Approximate agreement with BRAHMS data on the rapidity distribution of produced particles at top RHIC energies can be achieved if the complex shift of the time coordinate is comparable to the inverse of the saturation scale. The form of the stress tensor follows essentially from symmetry considerations, and it can be expressed in closed form.