Wounded nucleon model with realistic nucleon-nucleon collision profile and observables in relativistic heavy-ion collisions

TL;DR

This paper examines how using a realistic Gaussian nucleon-nucleon collision profile, instead of a hard-sphere model, affects key observables in relativistic heavy-ion collision simulations, highlighting the importance of accurate modeling.

Contribution

It demonstrates that adopting a realistic Gaussian collision profile significantly alters participant eccentricity and multiplicity fluctuation calculations in the wounded nucleon model.

Findings

Participant eccentricity coefficients decrease by 10-20% with the Gaussian profile.

Multiplicity fluctuations are reduced by 10-20% using the realistic profile.

Glauber Monte Carlo codes should incorporate the Gaussian collision profile for precision.

Abstract

We investigate the influence of the nucleon-nucleon collision profile (probability of interaction as a function of the nucleon-nucleon impact parameter) in the wounded nucleon model and its extensions on several observables measured in relativistic heavy-ion collisions. We find that the participant eccentricity coefficient, $\epsilon^\ast$, as well as the higher harmonic coefficients, $\epsilon_n^\ast$, are reduced by 10-20% for mid-peripheral collisions when the realistic (Gaussian) profile is used, as compared to the case with the commonly-used hard-sphere profile. Similarly, the multiplicity fluctuations, treated as the function of the number of wounded nucleons in one of the colliding nuclei, are reduced by 10-20%. This demonstrates that the Glauber Monte Carlo codes should necessarily use the realistic nucleon-nucleon collision profile in precision studies of these observables. The Gaussian collision profile is built-in in {\tt GLISSANDO}.