# 3+1d quasiparticle anisotropic hydrodynamics for ultrarelativistic heavy-ion collisions

## TL;DR

This paper introduces a 3+1d quasiparticle anisotropic hydrodynamics framework that effectively models the evolution of quark-gluon plasma in heavy-ion collisions, successfully matching experimental data from LHC Pb+Pb collisions.

## Contribution

It presents the first application of 3+1d aHydroQP to experimental heavy-ion collision data, incorporating shear and bulk viscosity with a self-consistent freezeout process.

## Key findings

- Good agreement with experimental observables
- Effective inclusion of viscous effects
- Successful modeling of particle spectra and flow

## Abstract

We present the first comparisons of experimental data with phenomenological results from 3+1d quasiparticle anisotropic hydrodynamics (aHydroQP). We compare charged-hadron multiplicity, identified-particle spectra, identified-particle average transverse momentum, charged-particle elliptic flow, and identified-particle elliptic flow produced in LHC 2.76 TeV Pb+Pb collisions. The dynamical equations used for the hydrodynamic stage utilize non-conformal aHydroQP. The resulting aHydroQP framework naturally includes both shear and bulk viscous effects in addition to higher-order non-linear transport coefficients. The 3+1d aHydroQP evolution obtained is self-consistently converted to hadrons using anisotropic Cooper-Frye freezeout performed on a fixed-energy-density hypersurface. The final production and decays of the primordial hadrons are modeled using a customized version of THERMINATOR 2. In this first study, we utilized smooth Glauber-type initial conditions and a single effective freeze-out temperature T_FO = 130 MeV with all hadronic species in full chemical equilibrium. With this rather simple setup, we find a very good description of many heavy-ion observables.