/ Experiment-HEP arXiv:0910.1029

Double Helicity Dependence of Jet Properties from Dihadrons in Longitudinally Polarized p+p Collisions at s**(1/2) = 200-GeV

Adare, A. ; Afanasiev, S. ; Aidala, C. ; Ajitanand, N.N. ; Akiba, Y. ; Al-Bataineh, H. ; Alexander, J. ; Aoki, K. ; Aphecetche, L. ; Armendariz, R. ; Aronson, S.H. ; Asai, J. ; Aschenauer, E.C. ; Atomssa, E.T. ; Averbeck, R. ; Awes, T.C. ; Azmoun, B. ; Babintsev, V. ; Bai, M. ; Baksay, G. ; Baksay, L. ; Baldisseri, A. ; Barish, K.N. ; Barnes, P.D. ; Bassalleck, B.

Published in: Phys.Rev.
Year: 2010
Vol.: D81
Page No: 012002
Pages: 10

Abstract: It has been postulated that partonic orbital angular momentum can lead to a significant double-helicity dependence in the net transverse momentum of Drell-Yan dileptons produced in longitudinally polarized p+p collisions. Analogous effects are also expected for dijet production. If confirmed by experiment, this hypothesis, which is based on semi-classical arguments, could lead to a new approach for studying the contributions of orbital angular momentum to the proton spin. We report the first measurement of the double-helicity dependence of the dijet transverse momentum in longitudinally polarized p+p collisions at sqrt(s) = 200 GeV from data taken by the PHENIX experiment in 2005 and 2006. The analysis deduces the transverse momentum of the dijet from the widths of the near- and far-side peaks in the azimuthal correlation of the dihadrons. When averaged over the transverse momentum of the triggered particle, the difference of the root-mean-square of the dijet transverse momentum between like- and unlike-helicity collisions is found to be -37 +/- 88(stat) +/- 14(syst) MeV/c.

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