Neutral pion production with respect to reaction plane in Au+Au collisions at RHIC-PHENIX

TL;DR

This paper investigates how neutral pion suppression varies with reaction plane angle in Au+Au collisions at RHIC, providing insights into parton energy loss mechanisms in quark-gluon plasma.

Contribution

It presents a new measurement of neutral pion suppression relative to the reaction plane using an upgraded detector at RHIC, enhancing understanding of jet quenching.

Findings

Improved reaction plane resolution with new detector

More precise measurement of neutral pion suppression

Insights into path length dependence of energy loss

Abstract

It has been observed that the yield of neutral pions at high transverse momentum (pT $>$ 5 GeV/c) region is strongly suppressed in central Au+Au collisions at Relativistic Heavy Ion Collider (RHIC), compared to the one expected in p+p collisions. This suppression may be due to an energy loss of hard scattered partons in the medium (jet quenching), that results in a decrease of the yield at a given pT. The magnitude of the suppression would depend on the path length of scattering partons in the medium, and therefore is associated with azimuthal angle from reaction plane in non-central collisions. Studying the path length dependence of energy loss would give additional information on understanding the energy loss mechanism. We discuss the parton energy loss mechanism using the nuclear modification factor ($R_{AA}$) of neutral pion with respect to reaction plane. A new reaction plane detector was installed in the PHENIX detector in RHIC Year-7 run, and improved the reaction plane resolution. More precise measurement of the hadron suppression with respect to path length is expected using the detector. I will report about analysis status of neutral pion production in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.