Preliminary Examination of Uncertainties due to Parton Distribution Functions in Far-Forward Neutrino Production at the Large Hadron Collider

Abstract

A large flux of neutrinos is expected in the forward direction of the pp collisions [1, 3] at the Large Hadron Collider (LHC) at CERN. Several experiments have recently been proposed at CERN to detect these neutrinos and discussion has started on the possibility of building a Forward Physics Facility grouping many of them. Among the others, the FASER-nu [2] proposal consists of a lead + emulsion neutrino detector at a distance of 480 m from the ATLAS interaction region along the tangent to the LHC beamline. Old calculations of neutrinos rates in the forward direction were done to leading order in the QCD perturbative series. We have included next-to-leading order (NLO) terms in our calculation. We have also studied the effect of incorporating a non-perturbative Gaussian intrinsic kT. This kT effect mimics the contribution from missing higher-order terms in QCD calculations. We present the study of uncertainties due to scale variations and Parton Distribution Function (PDF) variations in the production rate of $D_s^ \pm$ and tau neutrinos in the far-forward Production at the Large Hadron Collider. We compare our predictions with the LHCb data with $D_s^ \pm$ production in the rapidity range of [2–4.5] at the LHC. In our studies, for which we consider various modern PDF sets, we also include the comparison of predictions obtained by different dynamical central scale assumptions.