# Effect of bulk viscosity on interferometry correlations in ultrarelativistic heavy-ion collisions

## TL;DR

This study investigates how temperature-dependent bulk viscosity influences the evolution and interferometry measurements in ultrarelativistic heavy-ion collisions, revealing subtle effects on system lifetime and correlation radii.

## Contribution

It introduces a detailed 3+1D hydrodynamic model incorporating temperature-dependent bulk viscosity to analyze its impact on collision dynamics and interferometry observables.

## Key findings

- Increased bulk viscosity slightly extends system lifetime.
- Shape of freeze-out hypersurface is altered, with outer layers lasting longer.
- Reduction in R_out/R_side ratio improves agreement with experimental data.

## Abstract

A temperature dependent bulk viscosity coefficient is used in 3+1D hydrodynamic simulations. I study the effect of the increase of bulk viscosity around the critical temperature on the system dynamics in central Pb+Pb collisions at $\sqrt{s_{NN}}=2760$~GeV. With increasing bulk viscosity the life-time of the system increases slightly. Also the shape of the freeze-out hypersurface changes, the outer layers of the fireball live longer. This effect causes a small reduction of the ratio of two interferometry radii $R_{out}/R_{side}$, improving the agreement with experimental data.