Energy dependence of the ridge in high multiplicity proton-proton collisions

TL;DR

The paper shows that the observed ridge correlations in high multiplicity proton-proton collisions at 13 TeV align with predictions from the color glass condensate theory, challenging hydrodynamic explanations.

Contribution

It demonstrates that the ridge phenomena are consistent with the color glass condensate framework and constrains hydrodynamic models based on recent ATLAS measurements.

Findings

Ridge correlations agree with color glass condensate predictions.

Multiplicity dependence is energy independent due to saturation scale.

Hydrodynamic models are strongly constrained by azimuthal structure.

Abstract

We demonstrate that the recent measurement of azimuthally collimated, long range rapidity ("ridge") correlations in $\sqrt{s}=13$ TeV proton-proton (p+p) collisions by the ATLAS collaboration at the LHC are in agreement with expectations from the color glass condensate effective theory of high energy QCD. The observation that the integrated near side yield as a function of multiplicity is independent of collision energy is a natural consequence of the fact that multiparticle production is driven by a single semi-hard saturation scale in the color glass condensate framework. We argue further that the azimuthal structure of these recent ATLAS ridge measurements strongly constrain hydrodynamic interpretations of such correlations in high multiplicity p+p collisions.