A search for decays of heavy neutrinos

Abstract

A search for heavy neutrinos was conducted in the neutrino beam produced by the 400 GeV proton beam-dump and in the 400 GeV wide-band neutrino beam at CERN. A heavy neutrino associated with the τ lepton was searched for in the beam-dump experiment. No assumption on the nature of heavy neutrinos was made in the wide-band beam experiment. A search was made for neutrinos decaying into two electrons and a light neutrino. Since no events were observed, an upper limit on the neutrino mixing angles as a function of the neutrino mass is derived

Constraining neutrino superluminality from searches for sterile neutrino decays

“…2. We obtain similar limits from the negative results of CHARM experiment [10] which also performed searches for sterile neutrino decays. In this experiment, the CHARM detector of length l ≈ 12 m was exposed to wide-band neutrino beam produced by ∼ 1.4 × 10 18 protons with energies ∼ 400 GeV incident on a copper target.…”

“…To place a limit on δ in this case we require to have less than 85 events due to the bremsstrahlung (2). Also, the statistics for e + e − production from nothing was approximately doubled when detector was exposed to muon antineutrino flux produced by ∼ 5.7 × 10 18 protons on target [10]. For energy-independent δ we obtain from (7) after integrating over the whole available neutrino energy range 10-280 GeV, and taking into account the 44% efficiency [10] of e + e − -registration,…”

“…interesting limits one can expect from reanalysis of data collected at 35-meter length detector with CHARM calorimeter module installed, which was designed to search for heavy neutrinos produced by charmed meson decays [10].…”

Bounds on heavy sterile neutrinos revisited

“…We will review the existing limits on the mass and mixing of a heavy, mostly-sterile, neutrino [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]. We will then derive new bounds based on a re-analyses of the data from neutrino oscillations and accelerator neutrino experiments.…”

“…We will then derive new bounds based on a re-analyses of the data from neutrino oscillations and accelerator neutrino experiments. In the 10-390 MeV mass range we use the data from accelerator experiments [24,25,26,27]. For masses 8 MeV < ∼ m h < ∼ 105 MeV, we use the Super-Kamiokande (Super-K) data [28].…”