Prompt atmospheric neutrinos and muons: NLO vs LO QCD predictions

TL;DR

This paper compares NLO and LO QCD predictions for atmospheric muon and neutrino fluxes from charmed particle decays, finding that NLO fluxes can be approximated by scaled LO fluxes with about 10% accuracy.

Contribution

It demonstrates that NLO lepton fluxes are closely approximated by scaled LO fluxes, supporting previous modeling approaches and highlighting the impact of gluon distribution slopes.

Findings

NLO fluxes are within 10% of scaled LO fluxes.

The flux approximation depends on the gluon distribution slope.

Larger gluon slopes lead to higher lepton flux predictions.

Abstract

We compare the leading and next-to-leading order QCD predictions for the flux of atmospheric muons and neutrinos from decays of charmed particles. We find that the full NLO lepton fluxes can be approximated to within 10% by the Born--level fluxes multiplied by an overall factor of 2.2-2.4, which depends slightly on the PDF. This supports the approach in Thunman, Ingelman, Gondolo (1996). We also find that their very low lepton fluxes are due to the mild slope they used for the gluon distribution function at small momentum fractions, and that substantially larger lepton fluxes result when the slope of the gluon distribution function at small momentum fractions is larger.