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ics Colloquium
Friday, April 27, 2001
4:00 PM
Physics Building, Room 204
Note special time.
Brian Cole [Host: C. Dukes]
Columbia University
"The Baryon Junction and High-Energy Nuclear Collisions"
In the 1970's Veneziano suggested the existence of a set of diagrams in Regge theory that could allow the baryon number to be "extracted" from a baryon in a single step in high-energy hadronic interactions. Because no experimental evidence for these diagrams was found, the idea was largely forgotten. However, in recent years it has been resurrected and re-cast in terms of the so-called "baryon junction" a (possible) non-perturbative topological defect in the gluon fields within the baryon. In this picture, the junction plays the role of "bookkeeper" for baryon number conservation in high-energy collisions. Current theoretical models suggest that diagrams involving the exchange of the junction only become important in hadronic (e.g. p-p) collisions at collider energies. However, the junction may become active at much lower energies in nuclear collisions due to the multiple interaction of the incident nucleons. I will use results from a new generation of experiments studying proton-collisions at the Brookhaven National Laboratory AGS and CERN SPS accelerators to illustrate the possible role played by the junction in the "stopping" of the protons and in the abundant production of strange baryons and the production of anti-baryons. I will then discuss the possibility that the junction may be responsible for some of the anomolous results obtained from fixed-target heavy-ion experiments at the CERN SPS that were recently argued to provide evidence for quark-gluon plasma formation in high-energy nuclear collisions. I will discuss future studies of junction physics in fixed-target proton-nucleus experiments and in proton-proton and proton-nucleus collisions at the Relativistic Heavy Ion Collider. I will finish by highlighting some recent speculation that novel states of matter formed from "meshes" of junctions and anti-junctions may be created in heavy-ion collisions at RHIC.

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