Search for sterile neutrino mixing in the MINOS long-baseline experiment

Abstract

A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated non-interacting "sterile" neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18x10^{20} protons on target in which neutrinos of energies between ~500 MeV and 120 GeV are produced predominantly as nu_mu, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near detector sample shows that of the portion of the nu_mu flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles theta_{24} and theta_{34} are constrained to be less than 11 degrees and 56 degrees at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime tau_3/m_3 > 2.1x10^{-12} s/eV at 90% C.L..Comment: 18 pages, 17 figures. Published in Phys. Rev.

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

“…Bands are drawn to indicate the excluded regions. ments: CDHS [25], CCFR [26], MiniBooNE+SciBooNE [27] and MINOS [28], as well as by Super-Kamiokande [24]. Limits on |U τ 4 | 2 have been derived from the MINOS results on the neutral current interaction rate comparison between the near and the far detector [29] and more recently by the Super-Kamiokande analysis on matter effects for up-going atmospheric neutrinos [24].…”

DUNE Sensitivities to the mixing between Sterile and Tau Neutrinos

“…As usually assumed in previous analysis done by experimental collaborations [3,4,6,8], one can neglect the electron-sterile mixing angle since it is tightly constrain by reactor and solar experiments [16]. Therefore, along this letter we assume θ 14 = 0.…”

“…Otherwise, it is sensitive to lower values of the sterile mass splitting, below ∼ 0.5eV 2 , making possible to test a complementary ∆m 2 parameter space respect to what SBL experiments can probe. In particular, searches for an sterile oscillations at the far detector of LBL experiments have been performed by several collaborations using neutral-current (NC) events in their analysis [3,4,6,8]. Several phenomenological studies have considered the sterile effects at LBL experiments by the use of charge-current events [9,10,11,12,13,14,15].…”

“…The search for sterile oscillation frequency is perform within a model and the most economical one to accommodate an extra light sterile neutrino state is the so call 3 + 1 framework. From the negative observation of an sterile oscillation, several experimental collaborations have reported limits to the active-sterile mixing within the 3 + 1 framework [3,4,5,6,7,8].…”

Sterile neutrino oscillations in MINOS and hadron production in pC collisions

“…The model has also validity for the inverted hierarchy case. Results from this sterile neutrino model in MINOS are studied in this thesis and in [30]. Figure 2.5: The figure shows a possible neutrino mass ordering in case of a fourth mass state associated to a sterile neutrino.…”