Relativistic Heavy Ion Collision Studies at the LHC and RHIC

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It is a well-established fact that protons and neutrons are made up of smaller constituents called quarks and gluons. In collisions using two beams of heavy nuclei, a new state of matter is formed, called the quark-gluon plasma (QGP). This project will answer fundamental questions about the QGP, such as how matter is transformed from a collection of protons and neutrons to a free state where quarks and gluons can travel through space unhindered, much like they did in the primordial soup of matter following the Big Bang. Experiments will be carried out at the Relativistic Heavy Ion Collider (RHIC), located at Brookhaven National Laboratory, and at the Large Hadron Collider (LHC), located in Geneva, Switzerland. In order to look for signatures of how the transition to the QGP phase has occurred for a given beam energy, the Ohio State group will study the numbers of particles produced in the collisions along with the distribution and correlations of particle momenta. The goals for the high-energy program are three-fold. Firstly, to study the space-time properties of this extremely dense matter created in collisions between heavy nuclei at the highest achievable energies. The second is to study the bulk phase structure of Quantum Chromodynamics (QCD), believed to be the correct theory of the Strong interaction between quarks and gluons. This will be achieved by varying the conditions of the collision to lower energies, to probe the transition(s) between confined and deconfined matter. In particular, the group will perform a novel analysis as a function of the collision energy, measuring coordinate-space anisotropies and dynamics. Thirdly, they will take the tools developed to study bulk physics in heavy ion collisions, and apply them to proton- proton collisions at similar energies. They will look particularly for collective behavior (flow) in these collisions. If the initial reports of such flow in high-energy p+p collisions are confirmed at higher energies, this raises important issues about the nature of flow, and the nature of the initial self-interacting state, itself. In addition, there are broader impacts to society of this proposal in the areas of education, technology and computing.