Comparing the same-side "ridge" in CMS p-p angular correlations to RHIC p-p data

TL;DR

This paper compares the same-side ridge observed in high-energy proton-proton collisions at 7 TeV with lower-energy data at 0.2 TeV, suggesting the ridge is related to azimuthal quadrupole effects rather than a dense medium.

Contribution

It provides a detailed comparison showing the 7 TeV ridge is similar to lower-energy correlations and attributes it to azimuthal quadrupole effects rather than new medium formation.

Findings

7 TeV p-p correlations resemble 0.2 TeV data closely

The ridge is consistent with azimuthal quadrupole extrapolation

The ridge may result from known jet and quadrupole phenomena

Abstract

The CMS collaboration has recently reported the appearance of a same-side "ridge" structure in two-particle angular correlations from 7 TeV p-p collisions. The ridge in p-p collisions at 7 TeV has been compared to a ridge structure in more-central Au-Au collisions at 0.2 TeV interpreted by some as evidence for a dense, flowing QCD medium. In this study we make a detailed comparison between 0.2 TeV p-p correlations and the CMS results. We find that 7 TeV minimum-bias jet correlations are remarkably similar to those at 0.2 TeV, even to the details of the same-side peak geometry. Extrapolation of azimuth quadrupole systematics from 0.2 TeV suggests that the same-side ridge at 7 TeV is a manifestation of the azimuth quadrupole with amplitude enhanced by applied cuts.