Correlated wounded hot spots in proton-proton interactions

TL;DR

This study examines how spatial correlations between gluonic hot spots inside protons influence the initial collision geometry and eccentricities in proton-proton interactions across various energies, revealing that correlations affect the shape and fluctuations of the initial state.

Contribution

It introduces a Monte-Carlo Glauber model incorporating hot spot correlations to analyze their impact on initial collision conditions in proton-proton interactions, extending understanding of the hollowness effect.

Findings

Correlations reduce average eccentricities in minimum bias collisions.

In ultra-central events, correlations increase the probability of larger eccentricities.

Eccentricities show mild dependence on collision energy.

Abstract

We investigate the effect of non-trivial spatial correlations between proton constituents, considered in this work to be gluonic hot spots, on the initial conditions of proton-proton collisions from ISR to LHC energies, i.e. $\sqrt s\!=\!52.6,7000,13000$ GeV. The inclusion of these correlations is motivated by their fundamental role in the description of a recently observed new feature of $pp$ scattering at $\sqrt s\!=\!7$ TeV, the hollowness effect. Our analysis relies on a Monte-Carlo Glauber approach including fluctuations in the hot spot positions and their entropy deposition in the transverse plane. We explore both the energy dependence and the effect of spatial correlations on the number of wounded hot spots, their spatial distribution and the eccentricities, $\varepsilon_n$, of the initial state geometry of the collision. In minimum bias collisions we find that the inclusion of short range repulsive correlations between the hot spots reduces the value of the eccentricity ($\varepsilon_2$) and the triangularity ($\varepsilon_3$). In turn, upon considering only the events with the highest entropy deposition i.e. the ultra-central ones, the probability of having larger $\varepsilon_{2,3}$ increases significantly in the correlated scenario. Finally, the eccentricities show a quite mild energy dependence.