31st International Workshop on Deep Inelastic Scattering

Odderon Mechanism for Transverse Single Spin Asymmetry in pp and pA Collisions

Non programmé

20m

Maison MINATEC, Grenoble, FRANCE

Regular parallel talk WG2: Small-x, Diffraction and Vector Mesons

Orateur

Eric Andreas Vivoda (Physics department, Faculty of Science, University of Zagreb)

Description

Kovchegov and Sievert showed that the phase required for Transverse Single Spin Asymmetries (TSSA) in $q^\uparrow p$ and $q^\uparrow A$ collisions can be generated by QCD odderon [1]. Their results for TSSA possess interesting nuclear dependence that was recently measured at RHIC [2,3]. We consider $p^\uparrow p$ and $p^\uparrow A$ collisions and show that the contribution in [1] comes from the twist-3 distribution known as $g_T$ distribution [4]. However, the total twist-3 polarized cross section, in addition to the intrinsic $g_T$ distribution, contains also the so-called kinematical and dynamical part, the latter arising from Efremov-Teryaev-Qiu-Sterman (ETQS) functions [5,6,7]. Motivated by results from [1], we firstly neglected dynamical twist-3 contributions (Wandzura-Wilczek (WW) approximation [8]) and calculated the polarized cross section up to next-to-leading order, as in [1], but also taking into account all possible partonic channels [4]. We proved that in the WW approximation the polarized cross section is exactly zero, which proves that there is no TSSA in $p^\uparrow p$ and $p^\uparrow A$ collisions arising from odderon at this level. In the next step [Benić, Vivoda, in preparation] we are taking into account the ETQS contribution and compute the leading order polarized cross section. We reproduce the known soft gluon pole contribution in the saturation framework [9]. Additionally we identify a completely new contribution coming from combination of the non-pole ETQS function and the odderon.

References:

[1] Y. V. Kovchegov and M. D. Sievert, Phys. Rev. D 86, 034028 (2012), [Erratum: Phys.Rev.D 86, 079906 (2012)].
[2] PHENIX Collaboration, C. Aidala et. al., Phys.Rev.Lett. 123, 122001 (2019).
[3] Star Collaboration, J. Adam et. al., Phys.Rev.D. 103, 072005 (2021).
[4] S. Benić, D. Horvatić, A. Kaushik and E. A. Vivoda, Phys. Rev D 106, 114025 (2022).
[5] S. Benić, Y. Hatta, H.-n. Li, and D.-J. Yang, Phys. Rev. D 100, 094027 (2019).
[6] A.V. Eferemov and O.V. Teryaev, Sov. J. Nucl. Phys. 36, 140 (1982).
[7] J. W. Qiu and G.F. Sterman, Phys. Rev. Lett. 67, 2264 (1991).
[8] S. Wandzura and F. Wilczek, Phys. Lett. B 72, 195 (1977).
[9] Y. Hatta, B.-W. Xiao, S. Yoshida and F. Yuan, Phys. Rev. D 94, 054013 (2016).