Prompt neutrinos and intrinsic charm at SHiP

TL;DR

This paper evaluates the impact of intrinsic charm and transverse momentum effects on the neutrino flux from charm decays in the SHiP experiment, highlighting how these factors influence event predictions and potential constraints on intrinsic charm models.

Contribution

It introduces a comprehensive model including intrinsic charm and transverse momentum effects for predicting neutrino fluxes in SHiP, improving upon previous perturbative QCD estimates.

Findings

Intrinsic transverse momentum reduces tau neutrino event estimates by about threefold.

Intrinsic charm can significantly increase neutrino event counts from charm decays.

Neutrino measurements can constrain models of intrinsic charm.

Abstract

We present a new evaluation of the far-forward neutrino plus antineutrino flux and number of events from charm hadron decays in a 400 GeV proton beam dump experiment like the Search for Hidden Particles (SHiP). Using next-to-leading order perturbative QCD and a model for intrinsic charm, we include intrinsic transverse momentum effects and other kinematic angular corrections. We compare this flux to a far-forward flux evaluated with next-to-leading order perturbative QCD, without intrinsic transverse momentum, that used the angular distribution of charm quarks rather than the neutrinos from their decays. The tau neutrino plus antineutrino number of events in the perturbative QCD evaluation is reduced by a factor of about three when intrinsic transverse momentum and the full decay kinematics are included. We show that intrinsic charm contributions can significantly enhance the number of events from neutrinos from charm hadron decays. Measurements of the number of events from tau neutrino plus antineutrino interactions and of the muon charge asymmetry as a function of energy can be used to constrain intrinsic charm models.