TY - JOUR
T1 - Single transverse-spin asymmetry in very forward and very backward neutral particle production for polarized proton collisions at sqrt(s) = 200 GeV
AU - Fukao, Y.
AU - Togawa, M.
AU - Bazilevsky, A.
AU - Bland, L. C.
AU - Bogdanov, A.
AU - Bunce, G.
AU - Deshpande, A.
AU - En'yo, H.
AU - Fox, B. D.
AU - Goto, Y.
AU - Haggerty, J. S.
AU - Imai, K.
AU - Lenz, W.
AU - von Lintig, D.
AU - Liu, M. X.
AU - Makdisi, Y. I.
AU - Muto, R.
AU - Nurushev, S. B.
AU - Pascuzzi, E.
AU - Purschke, M. L.
AU - Saito, N.
AU - Sakuma, F.
AU - Stoll, S. P.
AU - Tanida, K.
AU - Tojo, J.
AU - Watanabe, Y.
AU - Woody, C. L.
N1 - Funding Information:
We thank the staff of the RHIC project, Collider-Accelerator, and Physics Departments at BNL and the staff of PHENIX participating institutions for their vital contributions. We thank the staff of SLAC and the SLAC facility for support and use of the Final Focus Test Beam. We also thank S. White of Brookhaven for loan on short notice of the ZDC module. We acknowledge support from the Department of Energy and NSF (USA), MEXT and JSPS (Japan).
PY - 2007/7/12
Y1 - 2007/7/12
N2 - 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 AN = (- 0.090 ± 0.006 ± 0.009) × (1.0-0.24+0.47) 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 π0, and backward neutron, photon, and π0 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.
AB - 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 AN = (- 0.090 ± 0.006 ± 0.009) × (1.0-0.24+0.47) 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 π0, and backward neutron, photon, and π0 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.
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U2 - 10.1016/j.physletb.2007.05.049
DO - 10.1016/j.physletb.2007.05.049
M3 - Article
AN - SCOPUS:34250794426
SN - 0370-2693
VL - 650
SP - 325
EP - 330
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
IS - 5-6
ER -