DIS2023: XXX International Workshop on Deep-Inelastic Scattering and Related Subjects

Transverse Single Spin Asymmetry for Inclusive and Diffractive Electromagnetic Jets at Forward Rapidity in p↑+p Collisions at s=200 GeV and 510 GeV at STAR

28 Mar 2023, 16:50

20m

105AB (MSU Kellogg Center)

Parallel talk WG5: Spin and 3D Structure WG5

Speaker

Xilin Liang (University of California, Riverside)

Description

There have been numerous attempts in the last couple of decades to understand the origin of the unexpectedly large transverse single spin asymmetry ($A_N$) of inclusive hadron production at forward rapidities observed in $p^{\uparrow }$+$p$ collisions at different center-of-mass energies ($\sqrt{s}$). The current theoretical framework to explain such a puzzle includes the twist-3 contributions in the collinear factorization framework, and 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 the large $A_N$ might come from diffractive processes, according to the previous analyses of $A_N$ for forward ${\pi }^0$ and electromagnetic jets in $p^{\uparrow }$+$p$ collisions at STAR [1]. The STAR Forward Meson Spectrometer (FMS) is an electromagnetic calorimeter, which can detect photons, neutral pions, and eta mesons, with a pseudorapidity coverage of $2.6<\eta <4.2$. In 2015 and 2017, STAR collected large $p^{\uparrow }$+$p$ data sets at $\sqrt{s}=200$ GeV and $\sqrt{s}=510$ GeV, which provide a great opportunity to measure $A_N$ for inclusive and diffractive electromagnetic jets. In this talk, we will present the preliminary results and analysis updates on $A_N$ for inclusive and diffractive electromagnetic jets in the FMS at $\sqrt{s}=200$ GeV and $510$ GeV. Also, we will present the comparison of $A_N$ between inclusive and diffractive electromagnetic jets.

[1] (STAR) J. Adam et al., Phys. Rev. D 103, 092009 (2021)

Presentation materials

Liang_DIS_2023.pdf

Proceedings