Anisotropic hydrodynamics with number-conserving kernels

TL;DR

This paper compares anisotropic hydrodynamics results using different collisional kernels, explicitly enforces number conservation with a dynamical chemical potential, and examines the impact on system evolution and attractors.

Contribution

It introduces a method to incorporate number conservation via a dynamical chemical potential into anisotropic hydrodynamics and compares outcomes with different collisional kernels.

Findings

Number conservation significantly affects aHydro dynamics.

The aHydro attractor remains largely unchanged despite corrections.

Quantitative differences are observed in microscopic parameters and energy-momentum components.

Abstract

We compare anisotropic hydrodynamics (aHydro) results obtained using the relaxation-time approximation (RTA) and leading-order (LO) scalar \lambda \phi^4 collisional kernels. We extend previous work by explicitly enforcing number conservation through the incorporation of a dynamical chemical potential (fugacity) in the underlying aHydro distribution function. We focus on the case of a transversally homogenous and boost-invariant system obeying classical statistics and compare the relevant moments of the two collisional kernels. We then compare the time evolution of the aHydro microscopic parameters and components of the energy-momentum tensor. We also determine the non-equilibrium attractor using both the RTA and LO conformal \lambda \phi^4 number-conserving kernels. We find that the aHydro dynamics receives quantitatively important corrections when enforcing number conservation, however, the aHydro attractor itself is not modified substantially.