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Friday, April 27, 2001
Physics Building, Room 204
Note special time.
[Host: C. Dukes]
"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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