Speaker
Description
Spin-1 hadrons provide a unique opportunity to investigate tensor polarization, leading to novel partonic structures absent in spin-1/2 hadrons. Motivated by ongoing and future measurements at facilities such as JLab, it is important to clarify the role of higher-twist contributions, which may become significant in the moderate-$Q^2$ region. In this work [1], we study the tensor-polarized twist-3 collinear parton distribution function (PDF) $f_{LT}$ and its phenomenological implications for the spin-1 deuteron.
For tensor-polarized PDFs, a Wandzura-Wilczek-like relation and a Burkhardt-Cottingham-like sum rule exist [2]. Recently, we derived these relations within the framework of the local operator product expansion (OPE), providing a field-theoretical foundation for the twist-3 structure of spin-1 hadrons [3]. Using these relations together with the phenomenological twist-2 distribution $f_{1LL}(x)$ extracted from HERMES measurements of the deuteron's tensor-polarized structure function $b_1$ [4], we present a quantitative estimate of the twist-3 distribution $f_{LT}(x)$. Our analysis suggests that twist-3 effects could be non-negligible. These results provide quantitative guidance for forthcoming experimental studies of tensor polarization in spin-1 hadrons.
[1] S. Kumano and K. Kuroki, Phys. Lett. B 875 (2026) 140348.
[2] S. Kumano and Q.-T. Song, JHEP 09 (2021) 141.
[3] S. Kumano and K. Kuroki, arXiv:2605.00430.
[4] S. Kumano, Phys. Rev. D 82 (2010) 017501.