[Show abstract][Hide abstract] ABSTRACT: In this document the PHENIX collaboration proposes a major upgrade to the
PHENIX detector at the Relativistic Heavy Ion Collider. This upgrade, sPHENIX,
enables an extremely rich jet and beauty quarkonia physics program addressing
fundamental questions about the nature of the strongly coupled quark-gluon
plasma (QGP), discovered experimentally at RHIC to be a perfect fluid. The
startling dynamics of the QGP on fluid-like length scales is an emergent
property of quantum chromodynamics (QCD), seemingly implicit in the Lagrangian
but stubbornly hidden from view. QCD is an asymptotically free theory, but how
QCD manifests as a strongly coupled fluid with specific shear viscosity near
$T_C$, as low as allowed by the uncertainty principle, is as fundamental an
issue as that of how confinement itself arises.
[Show abstract][Hide abstract] ABSTRACT: The PHENIX collaboration presents a concept for a major upgrade to the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). This upgrade, referred to as sPHENIX, brings exciting new capability to the RHIC program by opening new and important channels for experimental investigation and utilizing fully the luminosity of the recently upgraded RHIC facility. sPHENIX enables a compelling jet physics program that will address fundamental questions about the nature of the strongly coupled quark-gluon plasma discovered experimentally at RHIC to be a perfect fluid. The upgrade concept addresses specific questions whose answers are necessary to advance our understanding of the quark-gluon plasma: (1) How to reconcile the observed strongly coupled quark-gluon plasma with the asymptotically free theory of quarks and gluons? (2) What are the dynamical changes to the quark-gluon plasma in terms of quasiparticles and excitations as a function of temperature? (3) How sharp is the transition of the quark-gluon plasma from the most strongly coupled regime near Tc to a weakly coupled system of partons known to emerge at asymptotically high temperatures? In three Appendices, we detail the additional physics capabilities gained through further upgrades: (A) two midrapidity detector additions, (B) a forward rapidity upgrade, and (C) an evolution to an ePHENIX detector suitable for a future Electron Ion Collider at RHIC.