Non-flow correlations and elliptic flow fluctuations in gold-gold collisions at sqrt(s_NN)= 200 GeV

TL;DR

This study measures elliptic flow fluctuations in gold-gold collisions at 200 GeV, accounting for non-flow effects, and finds fluctuations consistent with initial spatial nucleon fluctuations, challenging the idea that non-flow alone explains observed anisotropies.

Contribution

Introduces a new analysis method to separate non-flow correlations from elliptic flow fluctuations in heavy-ion collisions.

Findings

Relative elliptic flow fluctuations of 30-40% observed.

Long-range non-flow correlations would need to be much stronger to explain fluctuations without intrinsic flow.

Results align with predictions based on initial nucleon spatial fluctuations.

Abstract

This paper presents results on event-by-event elliptic flow fluctuations in Au+Au collisions at sqrt(s_NN)=200Gev, where the contribution from non-flow correlations has been subtracted. An analysis method is introduced to measure non-flow correlations, relying on the assumption that non-flow correlations are most prominent at short ranges (Delta eta < 2). Assuming that non-flow correlations are of the order that is observed in p+p collisions for long range correlations (Delta eta > 2), relative elliptic flow fluctuations of approximately 30-40% are observed. These results are consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. It is found that the long range non-flow correlations in Au+Au collisions would have to be more than an order of magnitude stronger compared to the p+p data to lead to the observed azimuthal anisotropy fluctuations with no intrinsic elliptic flow fluctuations.