Phenomenological Estimate for the Longitudinal Unpolarized Structure Function in Semi-inclusive Deep Inelastic Scattering
Abstract
We present a phenomenological study of the longitudinal unpolarized structure function FUU,L in semi-inclusive deep inelastic scattering (SIDIS) and its ratio with the transverse structure function, R SIDIS=FUU,L/FUU,T. We study their transverse-momentum dependence, combining for the first time low- and high-transverse-momentum contributions across the kinematic range relevant to SIDIS measurements. At low transverse momentum, FUU,L is power suppressed, making it sensitive to next-to-next-to-leading-power dynamics in the unpolarized sector. We find that this contribution can be sizable, with R SIDIS≃ 0.3 at low transverse momentum and hard scale, producing a correction of the order of 10% to transverse-momentum-integrated observables. Although these estimates remain subject to theoretical uncertainties, our results indicate that accounting for FUU,L is likely to be important for the interpretation of SIDIS multiplicities and motivate dedicated measurements of R SIDIS to better constrain the longitudinal contribution.
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BibTeX
@misc{bacchetta2026phenomenological,
title = {{Phenomenological Estimate for the Longitudinal Unpolarized Structure Function in Semi-inclusive Deep Inelastic Scattering}},
author = {Alessandro Bacchetta and Matteo Cerutti and Leonard Gamberg and Richard Whitehill},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.06628},
eprint = {2610.06628},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05835137v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Phenomenological Estimate for the Longitudinal Unpolarized Structure Function in Semi-inclusive Deep Inelastic Scattering
AU - Alessandro Bacchetta
AU - Matteo Cerutti
AU - Leonard Gamberg
AU - Richard Whitehill
PY - 2026
DA - 2026/10/05
PB - HAL
DO - 10.48550/arxiv.2610.06628
UR - https://hal.science/hal-05835137v1
AB - We present a phenomenological study of the longitudinal unpolarized structure function F_UU,L in semi-inclusive deep inelastic scattering (SIDIS) and its ratio with the transverse structure function, R_ SIDIS=F_UU,L/F_UU,T. We study their transverse-momentum dependence, combining for the first time low- and high-transverse-momentum contributions across the kinematic range relevant to SIDIS measurements. At low transverse momentum, F_UU,L is power suppressed, making it sensitive to next-to-next-to-leading-power dynamics in the unpolarized sector. We find that this contribution can be sizable, with R_ SIDIS≃ 0.3 at low transverse momentum and hard scale, producing a correction of the order of 10% to transverse-momentum-integrated observables. Although these estimates remain subject to theoretical uncertainties, our results indicate that accounting for F_UU,L is likely to be important for the interpretation of SIDIS multiplicities and motivate dedicated measurements of R_ SIDIS to better constrain the longitudinal contribution.
ER -