Highlights from STAR (II) - Hard Probes of the Initial and Final State -

TL;DR

This paper reviews recent STAR collaboration results on hard probes in heavy-ion collisions, exploring initial state effects like saturation at low x, and final state modifications including jet quenching and hadron suppression, to understand partonic energy loss.

Contribution

It presents new experimental measurements at forward rapidities, di-jet and jet analyses, and nuclear modifications, providing comprehensive insights into initial and final state effects at RHIC.

Findings

Evidence for saturation effects at low x in d+Au collisions.

Quantitative measurements of jet quenching and nuclear modifications.

Constraints on partonic energy loss mechanisms in heavy-ion collisions.

Abstract

Highlights of recent results from the STAR collaboration focusing on hard probes of the initial and final state are presented. New results at forward rapidities in d+Au collisions at low $x$ are utilized to study the possible onset of saturation effects at RHIC energies. New reference measurements, $\Upsilon$ production, nuclear-$k_T$ via di-jets in d+Au collisions, and jet quantities in p+p collisions will be discussed. Final state nuclear modifications of $J/\psi$ and identified hadrons in heavy-ion collisions will be presented. In addition to di(multi)-hadron and direct $\gamma$-hadron correlations, new results from full-jet reconstruction in Au+Au collisions will be discussed with respect to the p+p reference measurements. These measurements can be used to put further constraints on the underlying mechanisms of partonic energy loss in heavy-ion collisions at RHIC.