Study of tau-neutrino production at the CERN SPS

Abstract

Lepton universality in tau-neutrino (ν τ ) scattering has been poorly tested. More precise measurement of the ν τ cross section would enable a search for new physics effects in ν τ -nucleon CC interactions. Such measurement also has practical importance for next-generation neutrino oscillation experiments and astrophysical ν τ observations. The DsTau project has been proposed at CERN SPS to study tau-neutrino production with the aim of providing important data for future ν τ measurements. For ν τ cross section measurements, the practical method of producing an artificial ν τ beam employs the sequential decay of D s mesons produced in high-energy proton interactions. However, there has been no experimental measurement of the D s differential production cross section in fixed-target experiments using proton beams, which leads to a large systematic uncertainty on the ν τ flux estimation. The DsTau project aims to reduce this uncertainty in the current cross section measurement from about 50% to 10% by measuring the D s differential production cross section. For this purpose, emulsion detectors with a 50-nm spatial resolution will allow the detection of D s → τ → X double kinks in a few mm range. Results from the beam tests conducted in 2016-2017 are presented together with a prospect for the pilot run in 2018 and the physics run in 2021.

Technical Proposal: FASERnu

“…FASERν expects high-energy particles (∼ TeV) at high density (O(10 5 )µ/cm 2 ). The reconstruction of these particles requires software dedicated to such a high-energy and high-density environment, for which the experience accumulated for the DsTau experiment (NA65) can be directly used [83,84]. As an example, the films may be aligned by using high-energy muon tracks.…”

NA65/DsTau: Study of tau-neutrino production at the CERN SPS

“…In a future experiment SHiP [7] at CERN, it is expected to collect thousands of ν τ interactions, providing a negligible statistical uncertainty in the cross section measurement. Thus the overall uncertainty of the cross section will be determined by the systematic uncertainties, especially by the ν τ flux uncertainty, which will be studied by this experiment [8,9]. The dominant source of ν τ in the accelerator-based neutrino beam is leptonic decays of D ± s mesons produced in proton-nucleus interactions.…”