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Double helicity asymmetry in inclusive midrapidity pi0 production for polarized p+p collisions at square root s = 200 GeV |
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| Authors: | Adler S S Afanasiev S Aidala C Ajitanand N N Akiba Y Al-Jamel A Alexander J Aoki K Aphecetche L Armendariz R Aronson S H Averbeck R Awes T C Babintsev V Baldisseri A Barish K N Barnes P D Bassalleck B Bathe S Batsouli S Baublis V Bauer F Bazilevsky A Belikov S Bjorndal M T Boissevain J G Borel H Brooks M L Brown D S Bruner N Bucher D Buesching H Bumazhnov V Bunce G Burward-Hoy J M Butsyk S Camard X Chand P Chang W C Chernichenko S Chi C Y Chiba J Chiu M Choi I J Choudhury R K Chujo T Cianciolo V Cobigo Y Cole B A Comets M P Constantin P Csanád M Csörgo T Cussonneau J P d'Enterria D Das K |
| Institution: | Brookhaven National Laboratory, Upton, New York 11973-5000, USA. |
| Abstract: | We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at sqrts]=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in 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 midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions. |
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