Charge balancing and the fall off of the ridge

TL;DR

This paper uses hydrodynamic models to explain the fall-off of the same-side ridge in two-dimensional correlation functions of charged hadrons in heavy-ion collisions, attributing it to local charge conservation effects.

Contribution

It demonstrates that local charge conservation at late stages can explain the ridge fall-off, improving understanding of correlation structures in heavy-ion collision data.

Findings

Reproduces azimuthal flow patterns using Glauber initial conditions.

Explains ridge fall-off as a local charge conservation effect.

Shows increased harmonic flow coefficients for unlike-sign pairs.

Abstract

Two-dimensional correlation functions in $\Delta\eta-\Delta \phi$ for charged hadrons emitted in heavy-ion collisions are calculated in event-by-event hydrodynamics. With the Glauber model for the initial density distributions in the transverse plane and elongated density profiles in the longitudinal direction, the flow patterns in the azimuthal angle of the two-dimensional correlation function are properly reproduced. We show that the additional fall-off of the same-side ridge in the longitudinal direction can be explained as an effect of local charge conservation at a late stage of the evolution. This additional non-flow effect increases the harmonic flow coefficients for the unlike-sign particle pairs.