Phenomenological estimate for the longitudinal structure function in SIDIS

5 May 2026, 09:20
20m
Sala IMPERIALE B. (Hotel Carlton)

Sala IMPERIALE B.

Hotel Carlton

Talk WG5 Spin and 3D Structure WG5 Spin and 3D-structure

Speaker

Richard Whitehill (Old Dominion University / Jefferson Lab)

Description

Obtaining a unified description of the transverse-momentum spectrum of hadrons produced in SIDIS through the $W+Y$ construction has been a primary focus within the nuclear physics community the last few decades. A critical element of this framework is the matching between low- and high-$q_T$ structure functions. While some unpolarized SIDIS structure functions match consistently at leading power, others do not, although recent studies suggest that subleading contributions may be phenomenologically relevant. In this work, we investigate the impact of such effects by studying the ratio $R_{\rm SIDIS} = F_{UU,L}/F_{UU,T}$, for which the longitudinal structure function $F_{UU,L}$ is purely sub-leading in the low-$q_T$ region, making this observable a sensitive probe of next-to-leading-power dynamics in the unpolarized sector. We implement various models which induce a sub-leading $F_{UU,L}$ and study their impact on predictions for $R_{\rm SIDIS}$. Our results highlight the importance of sub-leading effects as well as a consistent treatment of the transverse momentum spectrum for the prediction of $R_{\rm SIDIS}$.

Speaker confirmation Yes

Authors

Dr Alessandro Bacchetta (Istituto Nazionale di Fisica Nucleare) Dr Leonard Gamberg Dr Matteo Cerutti Richard Whitehill (Old Dominion University / Jefferson Lab)

Presentation materials