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Double Helicity Asymmetry in Inclusive Mid-Rapidity neutral pion Production for Polarized p+p Collisions at sqrt(s)=200 GeV

the PHENIX Collaboration·S. Adler
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Abstract

We present a measurement of the double longitudinal spin asymmetry in inclusive pi^0 production in polarized proton-proton collisions at sqrt(s)=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 26%. The measurements are the first of a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at mid-rapidity, where next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculations describe the unpolarized cross section well. The observed asymmetry is small and is compared with a NLO pQCD calculation with a range of polarized gluon distributions.

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the PHENIX Collaboration, S. Adler. 2004-04-21. Double Helicity Asymmetry in Inclusive Mid-Rapidity neutral pion Production for Polarized p+p Collisions at sqrt(s)=200 GeV. https://doi.org/10.1103/physrevlett.93.202002

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