Forward QCD Physics at a Collider

Abstract: 

Over the past 16 years, a series of calorimeters have been used for measurements of forward particle production in colliding beam experiments at RHIC in exploratory research. Collisions between two protons, a light-ion and a heavy ion, and between two heavy ions have been studied. Proton collisions are spin polarized in the collision energy range from 200 to 500 GeV. Results for spin asymmetries and cross sections for forward production have been challenging to understand using QCD. Some of this data has been described by saturation of the gluon density in heavy nuclei, as many theorists expect to happen at RHIC collision energies. Initial explanations of large spin effects for forward pion production involved orbital motion within the proton. Forward jet pairs produced in heavy ion collisons may prove useful for new particle searches. This talk will review the results of these explorations, plans formulated for subsequent explorations, and discuss broad implications of the results to both QCD and others areas of physics.