Semi-Holography for Heavy Ion Collisions: Self-Consistency and First Numerical Tests

TL;DR

This paper extends a semi-holographic model for heavy-ion collisions by ensuring self-consistent couplings between Yang-Mills fields and an infrared AdS/CFT sector, enabling combined evolution of weakly and strongly coupled components, with initial numerical tests showing rapid convergence.

Contribution

It introduces a self-consistent coupling framework between CGC-based Yang-Mills fields and an infrared holographic sector, including topological charge interactions, with initial numerical validation.

Findings

Conserved energy-momentum tensor explicitly constructed.

Coupling of topological charge density included.

Numerical tests show rapid convergence of the iterative scheme.

Abstract

We present an extended version of a recently proposed semi-holographic model for heavy-ion collisions, which includes self-consistent couplings between the Yang-Mills fields of the Color Glass Condensate framework and an infrared AdS/CFT sector, such as to guarantee the existence of a conserved energy-momentum tensor for the combined system that is local in space and time, which we also construct explicitly. Moreover, we include a coupling of the topological charge density in the glasma to the same of the holographic infrared CFT. The semi-holographic approach makes it possible to combine CGC initial conditions and weak-coupling glasma field equations with a simultaneous evolution of a strongly coupled infrared sector describing the soft gluons radiated by hard partons. As a first numerical test of the semi-holographic model we study the dynamics of fluctuating homogeneous color-spin-locked Yang-Mills fields when coupled to a homogeneous and isotropic energy-momentum tensor of the holographic IR-CFT, and we find rapid convergence of the iterative numerical procedure suggested earlier.