Quantum Chromodynamics (QCD) predicts that
heavy nuclei collided at ultra relatavistic
energies will undergo a phase transition
from ordinary hadronic matter to a quark-gluon plasma (QGP).
Among the major goals of PHENIX and the other RHIC experiments are:
investigating the QCD prediction of a deconfined high-energy-density phase of matter,
searching for the quark gluon plasma (QGP)
exploring the physics of this new state of matter
PHENIX and the other RHIC detectors will also study the physics of
polarized proton collisions.
The main goal here is to uncover the secrets of
the spin structure of the proton.
Currently it is known that the three quarks
do not carry all of the spin of the proton. The rest of the spin might be
carried by the gluons, sea quarks, some combination of these or by some as
yet undiscovered mechanism.