Directed flow from parton spin-orbit coupling in pp and pA collisions

We point out a novel mechanism to generate cos⁡ϕ two-particle azimuthal correlation (‘directed flow’) in unpolarized proton-proton and proton-nucleus collisions in the forward rapidity region of the projectile proton. This is a direct consequence of the recently discovered strong spin-orbit coupling...

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Bibliographic Details
Main Authors: Sanjin Benić, Yoshitaka Hatta
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Physics Letters B
Online Access:http://www.sciencedirect.com/science/article/pii/S0370269325004708
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Summary:We point out a novel mechanism to generate cos⁡ϕ two-particle azimuthal correlation (‘directed flow’) in unpolarized proton-proton and proton-nucleus collisions in the forward rapidity region of the projectile proton. This is a direct consequence of the recently discovered strong spin-orbit coupling in gluons at small-x. The observable simultaneously serves as a unique probe into the double helicity parton distribution functions of the proton.
ISSN:0370-2693