Measurements of double-helicity asymmetries in inclusive J/ψ production in longitudinally polarized p+p collisions at √s = 510 GeV

Adare, A. and Makek, Mihael and Zou, L. (PHENIX Collaboration) (2016) Measurements of double-helicity asymmetries in inclusive J/ψ production in longitudinally polarized p+p collisions at √s = 510 GeV. Physical Review D, 94 (11). pp. 112008-10. ISSN 1550-7998

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Abstract

We report the double-helicity asymmetry, ALLJ/ψ, in inclusive J/ψ production at forward rapidity as a function of transverse momentum pT and rapidity |y|. The data analyzed were taken during √s=510 GeV longitudinally polarized p+p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J/ψ particles are predominantly produced through gluon-gluon scatterings, thus ALLJ/ψ is sensitive to the gluon polarization inside the proton. We measured ALLJ/ψ by detecting the decay daughter muon pairs μ+μ- within the PHENIX muon spectrometers in the rapidity range 1.2<|y|<2.2. In this kinematic range, we measured the ALLJ/ψ to be 0.012±0.010 (stat) ±0.003 (syst). The ALLJ/ψ can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x: one at moderate range x≈5×10-2 where recent data of jet and π0 double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x≈2×10- 3. Thus our new results could be used to further constrain the gluon polarization for x<5×10-2.

Item Type: Article
Keywords: p+p collision, gluon polarization, helicity assymetry
Date: 29 December 2016
Subjects: NATURAL SCIENCES > Physics
Additional Information: © 2016 American Physical Society. Received 19 August 2016. Published 29 December 2016.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 16 Sep 2017 16:45
Last Modified: 16 Sep 2017 16:45
URI: http://digre.pmf.unizg.hr/id/eprint/5561

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