Nonperturbative-transverse-momentum effects and evolution in dihadron and direct photon-hadron angular correlations in p+p collisions at √s=510 GeV

Adare, A. and Makek, Mihael and Vukman, Nikola and Zou, L. (PHENIX Collaboration) (2017) Nonperturbative-transverse-momentum effects and evolution in dihadron and direct photon-hadron angular correlations in p+p collisions at √s=510 GeV. Physical Review D, 95 (7). pp. 72002-19. ISSN 1550-7998

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Abstract

Dihadron and isolated direct photon-hadron angular correlations are measured in p+p collisions at √s=510 GeV. Correlations of charged hadrons of 0.7 < pT < 10 GeV=c with π0 mesons of 4 < pT < 15 GeV=c or isolated direct photons of 7 < pT < 15 GeV=c are used to study nonperturbative effects generated by initial-state partonic transverse momentum and final-state transverse momentum from fragmentation. The nonperturbative behavior is characterized by measuring the out-of-plane transverse momentum component pout perpendicular to the axis of the trigger particle, which is the high-pT direct photon or π0. Nonperturbative evolution effects are extracted from Gaussian fits to the away-side inclusivecharged-hadron yields for different trigger-particle transverse momenta (ptrig T ). The Gaussian widths and root mean square of pout are reported as a function of the interaction hard scale ptrig T to investigate possible transverse-momentum-dependent evolution differences between the π0-h and direct photon-h correlations and factorization breaking effects. The widths are found to decrease with ptrig T , which indicates that the Collins-Soper-Sterman soft factor is not driving the evolution with the hard scale in nearly back-to-back dihadron and direct photon-hadron production in p + p collisions. This behavior is in contrast to Drell-Yan and semi-inclusive deep-inelastic scattering measurements.

Item Type: Article
Keywords: spin production asymmetries ; deep-inelastic scattering ; proton-proton collisions ; final-state interactions ; jet fragmentation ; boson production ; color coherence ; hard-scattering ; Drell-Yan ; Phenix
Date: 4 April 2017
Subjects: NATURAL SCIENCES > Physics
Additional Information: © 2017 American Physical Society. Received 17 September 2016. Published 4 April 2017.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 29 Sep 2017 13:20
Last Modified: 01 May 2018 13:34
URI: http://digre.pmf.unizg.hr/id/eprint/5592

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