Differential Distributions for NLO Analyses of Charged Current Neutrino-Production of Charm

TL;DR

This work develops a fully differential NLO QCD framework for charged-current neutrino-iron charm production to enable precise extraction of the strange quark PDF from dimuon data. It addresses the challenge of unphysical delta and plus distributions in fully differential cross sections by proposing regularization via either Gaussian pT-smearing or finite-binning, with a two-step approach that combines fixed-order regularization and Sudakov-inspired smearing. Numerical results at fixed-target kinematics demonstrate rapidity distributions and the role of Sudakov logarithms, showing that sufficiently broad binning yields positive, detector-appropriate distributions. A FORTRAN code is provided to implement the fully differential distributions in experimental analyses and to facilitate MC-based acceptance corrections.

Abstract

Experimental analyses of charged current deep inelastic charm production -- as observed through dimuon events in neutrino-iron scattering -- measure the strangeness component of the nucleon sea. A complete analysis requires a Monte Carlo simulation to account for experimental detector acceptance effects; therefore, a fully differential theoretical calculation is necessary to provide complete kinematic information. We investigate the theoretical issues involved in calculating these differential distributions at Next-Leading-Order (NLO). Numerical results are presented for typical fixed target kinematics. We present a corresponding FORTRAN code suitable for experimental NLO analysis.

Figures (4)

• Figure 1: Relative acceptance ${\cal{A}}(z,\eta )$ induced from typical kinematic cuts (as detailed in the text) on the decay-muon for $E_\nu = 80\ {\rm GeV}$, $x=0.1$, $Q^2 = 10\ {\rm GeV}^2$.
• Figure 2: Binned differential distribution for CC neutrino-production of charm on an isoscalar target; the kinematics shown are for a typical wide-band beam on a fixed target: $E_\nu = 80\ {\rm GeV}$, $x=0.1$, $Q^2 = 10\ {\rm GeV}^2$.
• Figure 3: Binned differential distributions in the charm rapidity, $\eta$. Shown are results for a fine binning (100$\times$100) in $\eta \times z$ (left), and a broad binning (right) of 10$\times$5. The fine-binned results refer to $z$-bins centered around 0.105, 0.605 and 0.955, respectively, while the broad-binned results refer to 0.1, 0.7 and 0.9.
• Figure 4: Binned distribution in $z$ (left: $\eta$ integrated out) and $\eta$ (right: $z$ integrated out), each for a fine and a broad binning.