High Energy / Nuclear Theory / RIKEN seminars

[NT/RBRC hybrid seminar] On the odderon mechanism for transverse single spin asymmetry in the Wilczek-Wandzura approximation

by Prof. Sanjin Benic (Zagreb university)

Large Seminar Room (https://bnl.zoomgov.com/j/1614715193?pwd=WkwxODVWdzZzb29zQnZRVGp3VTBDQT09)

Large Seminar Room



I will discuss our recent work [1] where we are revisiting the odderon mechanism for transverse single spin asymmetry (SSA) that was originally suggested by Kovchegov and Sievert [2]. The characteristic point of this mechanism is a very strong nuclear suppression of the asymmetry, ~ A^-7/6 parametrically, that is potentially interesting for phenomenological reasons [3,4]. We first specify the relevant parton distribution function (PDF) as the intrinsic twist-3 gT distribution in agreement with the results in [2] when considered on the parton level. However, we carefully argue that, due to gauge invariance, the complete twist-3 cross section also contains kinematical and dynamical twist-3 PDFs, in addition to the intrinsic PDF. We have explicitly computed the polarized cross section using the Wandzura-Wilczek approximation, where the dynamical twist-3 contribution is dropped. Our finding is that the polarized cross section is exactly zero up to the next-to-leading order in the strong coupling for all possible partonic channels. We finally outline several opportunities by which the odderon mechanism for transverse SSA could be realized after all.

[1] SB, Horvatic, Kaushik, Vivoda, 2210.10353
[2] Kovchegov, Sievert, Phys. Rev. D 86 (2012) 034028
[3] PHENIX, Phys. Rev. Lett. 123 (2019) 122001
[4] STAR, Phys. Rev. D 103 (2021) 7, 072005