Neutral and Charged Current Semi-Inclusive Deep-Inelastic Scattering at NNLO QCD

TL;DR

We present analytic NNLO QCD corrections to the full SIDIS coefficient functions including neutral and charged current electroweak exchanges, targeted to EIC kinematics. A unified electroweak channel decomposition enables consistent assembly of all NC and CC contributions, including anomaly and NoW/Fcon distinctions, with results validated against photon-only benchmarks. Phenomenological studies show NNLO corrections are moderate and reduce scale uncertainties, while electroweak effects, especially at high $Q^2$, offer sensitivity to flavor structure of PDFs and FFs via lepton polarization and CC/NC asymmetries. The work provides essential NNLO precision for global analyses of PDFs and FFs with SIDIS data, aided by an accompanying ancillary file containing the full coefficient functions.

Abstract

Semi-inclusive hadron production in deep inelastic lepton-nucleon scattering (SIDIS) provides important probes of parton distributions and fragmentation functions. We compute the next-to-next-to-leading order (NNLO) massless QCD corrections to the full set of SIDIS coefficient functions in analytical form, accounting for electroweak neutral current and charged current exchange. Focusing on the kinematical setting of SIDIS measurements at the future Electron-Ion Collider (EIC), we quantify the impact of these corrections on the phenomenological predictions and their associated uncertainties. We study the impact of electroweak interference in the neutral current SIDIS process and investigate lepton polarisation asymmetries designed to enhance the sensitivity on charged current SIDIS.

Figures (35)

• Figure 1: Kinematics of semi-inclusive deep-inelastic scattering
• Figure 2: Representative diagrams for contributions to the flavour changing (a) and flavour-conserving $C_{qq,\mathrm{Fcon}}^{(2)}$ coefficient functions (b),(c). The identified final state parton is marked with an 'x'.
• Figure 3: Representative diagrams for the flavour-changing and flavour-conserving (non-singlet) contribution to the $C_{\bar{q} q}^{(2)}$ coefficient function. The identified final state parton is marked with an 'x'.
• Figure 4: Example diagrams for anomaly contributions to the neutral current case, vanishing only for even $n_f$. The identified final state parton is marked with an 'x'.
• Figure 5: Fiducial phase space covered by the four $Q^2$ bins of \ref{['eq:cutsQ2']} with kinematic cuts \ref{['eq:cutsxyz']} in the $(x,y)$ plane (left) or $(x,Q^2)$ plane (right).