Orateur
Description
In recent decades, there have been numerous efforts to unravel the origin of the unexpectedly significant transverse single spin asymmetry ($A_{N}$) observed in inclusive hadron productions at forward rapidities in $p^{\uparrow}$+$p$ collisions at various center-of-mass energies ($\sqrt{s}$). Several theories have been proposed to explain this phenomenon, including the twist-3 contributions within the collinear factorization framework, the transverse-momentum-dependent contributions from the initial-state quark and gluon (Sivers functions), and/or final-state Collins fragmentation functions. However, there are indications that diffractive processes might also play a role in the observed significant $A_{N}$, based on the previous analyses of $A_{N}$ for forward $\pi^{0}$ and electromagnetic jets (EM-jets) in $p^{\uparrow}$+$p$ collisions at STAR [1].
The STAR experiment provides an ideal opportunity to investigate the $A_{N}$ in single diffractive processes at forward rapidity using the Forward Meson Spectrometer and Roman Pot detectors.
This talk will present the preliminary findings on $A_{N}$ for both inclusive and single diffractive EM-jets at forward rapidity ($2.6 < \eta < 4.2$) in $p^{\uparrow}$+$p$ collisions at $\sqrt{s} =$ 200 GeV at STAR. The discussion will include a multi-dimensional analysis of $A_{N}$ for EM-jets in inclusive processes, with a focus on presenting the first preliminary results for $A_{N}$ in single diffractive processes. Additionally, there will be a discussion on the contribution of $A_{N}$ from single diffractive processes to the overall inclusive processes.
[1] (STAR) J. Adam et, al., Phys. Rev. D 103, 092009 (2021)
