Influence of collective nuclear vibrations on initial state eccentricities in Pb+Pb collisions

TL;DR

This paper investigates how collective quantum vibrations in lead nuclei influence initial geometric anisotropies in Pb+Pb collisions at the LHC, using a modified Monte Carlo Glauber model to better match experimental observations.

Contribution

It introduces a quantum-informed nucleon sampling method in the Glauber model that accounts for collective nuclear vibrations, improving the description of initial state eccentricities.

Findings

The modified model yields an $rac{ ext{epsilon}_2}{ ext{epsilon}_3}$ ratio of about 0.8 at near-central collisions.

This approach helps resolve the $v_2$-$v_3$ puzzle in heavy-ion collision modeling.

Quantum effects significantly impact initial geometric anisotropies in Pb+Pb collisions.

Abstract

We study within the Monte Carlo Glauber model the influence of collective quantum effects in the Pb nucleus on the azimuthal anisotropy coefficients $\epsilon_{2,3}$ in Pb+Pb collisions at the LHC energies. To account for the quantum effects, we modify the sampling of the nucleon positions by applying suitable filters that guarantee that the colliding nuclei have the mean squared quadrupole and octupole moments consistent with the ones extracted from the experimental quadrupole and octupole strength functions for the Pb nucleus with the help of the energy weighted sum rule. Our Monte Carlo Glauber model with the modified sampling of the nucleon positions leads to $\epsilon_2\{2\}/\epsilon_3\{2\}\approx 0.8$ at centrality $\lesssim 1$\%, which allows to resolve the $v_2$-to-$v_3$ puzzle.