Improving the description of dimuon production in neutrino-nucleus collisions using the SACOT-$χ$ scheme

TL;DR

The paper addresses constraining the strange-quark PDF in nuclei via dimuon production in neutrino-nucleus DIS by implementing a self-contained NLO GM-VFNS calculation in the SACOT-χ scheme. It combines semi-inclusive charm-hadron production with muon decay in a SIDIS-based framework, carefully treating heavy-quark mass effects and scale choices. The SACOT-χ scheme introduces up to ~20% corrections relative to previous SR-based estimates, and the results show good agreement with NuTeV data, illustrating the method's robustness for nuclear PDF analyses. This work provides a fully consistent GM-VFNS description of dimuon production, laying the groundwork for improved strange-quark constraints in nuclear PDFs and outlining future NNLO and fragmentation-function developments.

Abstract

Dimuon production in deeply inelastic scattering between neutrinos and nuclei plays an important role in constraining the strange-quark parton distribution functions (PDFs). Here, we present a self-contained calculation of this process consisting of a next-to-leading order semi-inclusive charmed-hadron production in the SACOT-$χ$ general-mass variable-flavor-number scheme, followed by a semi-leptonic decay of the charmed hadron. We find that invoking the SACOT-$χ$ scheme introduces modifications up to $20 \, \%$ in comparison to our previous esimates, where only kinematic mass effects were considered through the slow-rescaling variable. We reiterate our earlier observation that the effective acceptance correction - typically used in global PDF fits as a simplifying approximation - depends on the perturbative order, PDFs, scales, and also on the treatment of heavy-quark effects. We find good agreement with the corresponding data from the NuTeV experiment.

Figures (11)

• Figure 1: Diagrammatic depiction of dimuon production in neutrino-nucleus scattering. Relevant momenta are indicated in parentheses.
• Figure 2: Comparison of the scale choices $\mu^2=Q^2$ and $\mu^2=Q^2+m_c^2$ for dimuon production in neutrino scattering in NuTeV kinematics, computed with EPPS21 at NLO using the SR (top row) and SACOT (bottom row) schemes. The uncertainty bands depict the envelope of all 17 scale choice combinations for each central curve. The theoretical calculations, as well as the experimental NuTeV data, are normalized to the central value with $\mu^2=Q^2+m_c^2$.
• Figure 3: Comparison of the ZM, SR, and SACOT schemes for dimuon production in neutrino scattering in the NuTeV kinematics, computed with EPPS21 at NLO using the scale choice $\mu^2=Q^2+m_c^2$. The uncertainty bands depict the envelope of all 17 scale choice combinations for each central curve. The theoretical calculations, as well as the experimental NuTeV data, are normalized to the central SR value.
• Figure 4: Same as figure \ref{['fig:scheme_comparison_neutrino']}, but for antineutrino scattering.
• Figure 5: Comparison of the charm-quark masses $m_c=1.3GeV$ and $m_c=1.5GeV$ for dimuon production in neutrino scattering in the NuTeV kinematics, computed with EPPS21 (top row) and nNNPDF3.0 (bottom row) at NLO using the scale choice $\mu^2=Q^2+m_c^2$. The uncertainty bands depict the envelope of all 17 scale choice combinations for each central curve. The theoretical calculations, as well as the experimental NuTeV data, are normalized to the central value with $m_c=1.3GeV$.