Single Transverse-Spin Asymmetry in Very Forward and Very Backward Neutral Particle Production for Polarized Proton Collisions at sqrt{s} = 200 GeV

Abstract

In the 2001-2002 running period of the Relativistic Heavy Ion Collider (RHIC), transversely polarized protons were accelerated to 100 GeV for the first time, with collisions at sqrt{s} = 200 GeV. We present results from this run for single transverse spin asymmetries for inclusive production of neutral pions, photons and neutrons of the energy region 20 - 100 GeV for forward and backward production for angles between 0.3 mrad and 2.2 mrad with respect to the polarized proton direction. An asymmetry of A_N = (-0.090 +- 0.006 +- 0.009) x (1.0^{+0.47}_{-0.24}) was observed for forward neutron production, where the errors are statistical and systematic, and the scale error is from the beam polarization uncertainty. The forward photon and pi^0, and backward neutron, photon, and pi^0 asymmetries were consistent with zero. The large neutron asymmetry indicates a strong interference between a spin-flip amplitude, such as one pion exchange which dominates lower energy neutron production, and remaining spin non-flip amplitudes such as Reggeon exchange.

arXiv comment6 pages, 5 figures, 1 table, submitted to Phys. Lett. B

References in corpus (2)

• The RHIC Zero Degree Calorimeter
• Measurement of Analyzing Power for Proton-Carbon Elastic Scattering in the Coulomb-Nuclear Interference Region with a 22-GeV/c Polarized Proton Beam

Cited by in corpus (14)

• Inclusive cross section and double helicity asymmetry for π^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
• Inclusive cross section and double helicity asymmetry for pi^0 production in p+p collisions at sqrt(s) = 62.4 GeV
• The gluon spin contribution to the proton spin from the double helicity asymmetry in inclusive pi^0 production in polarized p+p collisions at sqrt(s)=200 GeV
• Cross section and double helicity asymmetry for eta mesons and their comparison to neutral pion production in p+p collisions at sqrt(s)=200 GeV
• Cross Section and Transverse Single-Spin Asymmetry of $\eta$ Mesons in $p^{\uparrow }+p$ Collisions at $\sqrt{s}=200$ GeV at Forward Rapidity
• Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV
• Event Structure and Double Helicity Asymmetry in Jet Production from Polarized p+p Collisions at sqrt(s) = 200 GeV
• Cross Sections and Transverse Single-Spin Asymmetries in Forward Jet Production from Proton Collisions at $\sqrt{s}=500$ GeV
• Nuclear dependence of the transverse-single-spin asymmetry for forward neutron production in polarized $p$$+$$A$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Single Spin Asymmetries in High Energy Reactions and Nonperturbative QCD Effects
• Transverse momentum dependent forward neutron single spin asymmetries in transversely polarized $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV
• Transverse single spin asymmetries of forward neutrons in $p$$+$$p$, $p$$+$Al, and $p$$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV as a function of transverse and longitudinal momenta
• Transverse target single-spin asymmetry in inclusive electroproduction of charged pions and kaons
• Transverse Single Spin Asymmetries in Hadronic Interactions: an experimental overview and outlook