Results from RHIC with Implications for LHC

TL;DR

The paper reviews RHIC experimental results, highlighting phenomena like particle suppression and thermal photon emission, and discusses their implications for understanding QCD matter and future LHC studies.

Contribution

It provides a comprehensive analysis of RHIC results, connecting them to earlier p-p data and emphasizing unresolved issues relevant for LHC physics.

Findings

Suppression of high pT particles observed at RHIC.

Exponential distribution of thermal photons in Au+Au collisions.

Unresolved mystery of equal suppression of light and heavy quark decay products.

Abstract

Results from the PHENIX experiment at RHIC in p-p and Au+Au collisions are reviewed from the perspective of measurements in p-p collisions at the CERN-ISR which serve as a basis for many of the techniques used. Issues such as J/Psi suppression and hydrodynamical flow in A+A collisions require data from LHC-Ions for an improved understanding. Suppression of high pT particles in Au+Au collisions, first observed at RHIC, also has unresolved mysteries such as the equality of the suppression of inclusive pi0 (from light quarks and gluons) and direct-single electrons (from the decay of heavy quarks) in the transverse momentum range 4< pT < 9 GeV/c. This disfavors a radiative explanation of suppression and leads to a fundamental question of whether the Higgs boson gives mass to fermions. Observation of an exponential distribution of direct photons in central Au+Au collisions for 1< pT <2 GeV/c where hard-processes are negligible and with no similar exponential distribution in p-p collisions indicates thermal photon emission from the medium at RHIC, making PHENIX at the moment ``the hottest experiment in Physics''.