Systematics of Heavy Quark Production at RHIC

TL;DR

This paper outlines a systematic approach to studying heavy quark production at RHIC, emphasizing the importance of accurate baseline measurements in proton-proton collisions to understand nuclear effects.

Contribution

It introduces a methodology for measuring nuclear gluon distributions and studying heavy quark energy loss using dilepton mass ratios at RHIC.

Findings

Proton-proton cross sections need to be measured precisely.

Dilepton mass ratios can reveal nuclear gluon distributions.

Normalizing $J/\psi$ production with $c\bar c$ helps isolate nuclear effects.

Abstract

We discuss a program for systematic studies of heavy quark production in $pp$, $pA$ and $AA$ interactions. The $Q \bar Q$ production cross sections themselves cannot be accurately predicted to better than 50% at RHIC. For studies of deviations in $Q \bar Q$ production such as those by nuclear shadowing and heavy quark energy loss, the $pp$ cross section thus needs to be measured. We then show that the ratio of $pA$ to $pp$ dilepton mass distributions can provide a measurement of the nuclear gluon distribution. With total rates and nuclear shadowing under control it is easier to study energy loss and to use $c \bar c$ as a normalization of $J/\psi$ production.