Extraction of transhelicity worm-gear distributions and opportunities at the Electron-Ion Collider in China

We present a global analysis of the transhelicity worm-gear distribution function, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msubsup><a:mi>g</a:mi><a:mrow><a:mn>1</a:mn><a:mi>T</a:mi></a:mrow><a:mo>⊥</a:mo></a:msubsup></a:math>, by fitting the longitudinal-transverse double-spin asymmetry data of the semi-inclusive deep inelastic scattering. The analysis is performed within the framework of transverse momentum dependent factorization and evolution. It is found that the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>u</c:mi></c:math>-quark favors a positive distribution and the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>d</e:mi></e:math>-quark favors a negative distribution, which is consistent with previous model calculations and phenomenological extractions. Based on the fit to existing world data, we also study the impact of the proposed Electron-Ion Collider in China and conclude that it can significantly improve the precision of the worm-gear distribution function and hence enhance our understanding of nucleon spin structures. Published by the American Physical Society 2024