Spin Dependence in Polarized [formula omitted] and [formula omitted] Elastic Scattering at Very Low Momentum Transfer t at RHIC

Abstract

Interference phenomena in (polarized) hadron collisions have often led to spectacular spin effects in the final state. These effects are expressed in terms of the spin observables, like the analyzing power AN. The interference of the electromagnetic spin-flip amplitude with a hadronic spin-nonflip amplitude in the elastic scattering of hadrons generates a significant AN at very low t ( 0.001 | t | 0.01 ( GeV / c ) 2 ) . This kinematical region is referred to as the Coulomb Nuclear Interference (CNI) region. A possible hadronic spin-flip amplitude can substantially modify the magnitude and shape of AN, which otherwise is exactly calculable. First results on AN in polarized proton-proton elastic scattering in the CNI region at 100 GeV from the 2004 polarized proton run at RHIC are presented. New results on AN in the elastic scattering of polarized protons off a carbon target over a wide energy range from 4 GeV to 100 GeV from AGS and RHIC are presented, as well. These results allow us to further study the spin dependence in elastic scattering and the mechanisms that generate these effects.