Measurements of the Correlation between Reconstructed Jets and the Reaction Plane in STAR at RHIC

TL;DR

This paper measures the correlation between reconstructed jets and the reaction plane in heavy ion collisions, revealing non-zero jet v2 that indicates pathlength-dependent parton energy loss in the medium.

Contribution

First measurement of jet v2 in Au+Au collisions at RHIC, using forward detectors to reduce bias and explore jet-medium interactions.

Findings

Jet v2 is non-zero, indicating pathlength-dependent energy loss.

Use of forward detectors reduces jet-event plane bias.

Results support models of medium-induced parton energy loss.

Abstract

The relationship between jet properties and the underlying geometry of the medium produced in heavy ion collisions can be explored through a measurement of the correlation between the axes of reconstructed jets and the reaction plane, defined as "jet v2." Such a measurement provides information on the pathlength dependence of medium-induced parton energy loss and may also be used to assess biases in jet-finding methods. We present first measurements of jet v2 in sqrt(sNN) = 200 GeV Au+Au collisions in the STAR experiment at RHIC. In order to reduce the artificial jet - event plane bias, which results from jet fragments being included in the event plane calculation, detectors at forward pseudorapidity are used to determine the event plane when measuring the v2 of reconstructed jets at mid-rapidity. These measurements demonstrate a non-zero jet v2, which is indicative of pathlength-dependent parton energy loss.