# (C) Other neutrino mixing results

The LSND collaboration reported in AGUILAR 2001 a signal which is consistent with ${{\overline{\mathit \nu}}_{{\mu}}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{e}}}$ oscillations. In a three neutrino framework, this would be a measurement of $\theta _{12}$ and $\Delta \mathit m{}^{2}_{21}$. This does not appear to be consistent with most of the other neutrino data. The MiniBooNE experiment, reported in AGUILAR-AREVALO 2007 , does a two-neutrino analysis which, assuming $\mathit CP$ conservation, rules out AGUILAR 2001 . However, the MiniBooNE antineutrino data reported in AGUILAR-AREVALO 2013A are consistent with the signal reported in AGUILAR 2001 . The following listings include results which might be relevant towards understanding these observations. They include searches for ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}$ , ${{\overline{\mathit \nu}}_{{\mu}}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{e}}}$ , sterile neutrino oscillations, and $\mathit CPT$ violation.

# Search for ${{\boldsymbol \nu}_{{\mu}}}$ or ${{\boldsymbol \nu}_{{e}}}$ $\rightarrow$ ${{\boldsymbol \nu}_{{s}}}$ INSPIRE search

VALUE CL% DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$<0.4$ 90 1
 2017 B
ICCB IceCube-DeepCore
$<8 \times 10^{-3}$ 95 2
 2017
T $\beta$ decay
$<0.01$ 90 3
 2017
NEOS
$<0.02$ 90 4
 2016
ICCB IceCube
$<4.5 \times 10^{-4}$ 95 5
 2016 B
MINOS, DayaBay
$<0.086$ 95 6
 2016 C
MINS
$<0.011$ 95 7
 2016 B
DAYA
8
 2001
MCRO matter effects
9
 2000
SKAM neutral currents + matter effects
1  AARTSEN 2017B uses three years of upward-going atmospheric neutrino data in the energy range of 10-60 GeV to constrain their disappearance into light sterile neutrinos. The reported limit sin$^2\theta _{24}$ $<$ 0.11 at 90$\%$ C.L. is for $\Delta$m${}^{2}_{41}$ = 1.0 eV${}^{2}$. We convert the result to sin$^22\theta _{24}$ for the listing. AARTSEN 2017B also reports cos $^2\theta _{24}\cdot{}$sin$^2\theta _{34}$ $<$ 0.15 at 90$\%$ C.L. for $\Delta$m${}^{2}_{41}$ = 1.0 eV${}^{2}$.
2  ABDURASHITOV 2017 use the Troitsk nu-mass experiment to search for sterile neutrinos with mass 0.1 - 2 keV. We convert the reported limit from $\mathit U{}^{2}_{e4}<$0.002 to sin$^22\theta _{14}<$0.008 assume $\mathit U_{e4}\sim{}$ sin$\theta _{14}$. The stated limit corresponds to the smallest $\mathit U{}^{2}_{e4}$. The exclusion curve begins at $\mathit U{}^{2}_{e4}$ of 0.02 for m$_{4}$ = 0.1 keV.
3  KO 2017 reports on short baseline reactor oscillation search ( ${{\overline{\mathit \nu}}_{{e}}}$ $\rightarrow$ ${{\overline{\mathit \nu}}_{{s}}}$ ), motivated be the so-called "reactor antineutrino anomaly". The experiment is conducted at 23.7 m from the core of unit 5 of the Hanbit Nuclear Power Complex in Korea. the reported limited on sin$^2(2\theta _{41})$ for sterile neutrinos was determined using the reactor antineutrino spectrum determined by the Daya Bay experiment for $\Delta$m${}^{2}_{14}$ around 0.55 eV${}^{2}$ where the sensitivity is maximal. A fraction of the parameter space derived from the "reactor antineutrino anomaly" is excluded by this work. Compared to reactor models an event excess is observed at about 5 MeV, in agreement with other experiments.
4  AARTSEN 2016 use one year of upward-going atmospheric muon neutrino data in the energy range of 320 GeV to 20 TeV to constrain their disappearance into light sterile neutrinos. Sterile neutrinos are expected to produce distinctive zenith distribution for these energies for 0.01 ${}\leq{}\Delta$m${}^{2}{}\leq{}$10 eV${}^{2}$. The stated limit is for sin$^22\theta _{24}$ at $\Delta$m${}^{2}$ around 0.3 eV${}^{2}$.
5  ADAMSON 2016B combine the results of AN 2016B, ADAMSON 2016C, and Bugey-3 reactor experiments to constrain ${{\mathit \nu}_{{\mu}}}$ to ${{\mathit \nu}_{{e}}}$ mixing through oscillations into light sterile neutrinos. The stated limit for sin$^22\theta _{ {{\mathit \mu}} {{\mathit e}} }$ is at $\vert \Delta$m${}^{2}_{41}\vert$ = 1.2 eV${}^{2}$.
6  ADAMSON 2016C use the NuMI beam and exposure of $10.56 \times 10^{20}$ protons on target to search for the oscillation of ${{\mathit \nu}_{{\mu}}}$ dominated beam into light sterile neutrinos with detectors at 1.04 and 735 km. The reported limit sin$^2(\theta _{24})$ $<$ 0.022 at 95$\%$ C.L. is for $\vert \Delta$m${}^{2}_{41}\vert$ = 0.5 eV${}^{2}$. We convert the result to sin$^2(2\theta _{24})$ for the listing.
7  AN 2016B utilize 621 days of data to place limits on the ${{\overline{\mathit \nu}}_{{e}}}$ disappearance into a light sterile neutrino. The stated limit corresponds to the smallest sin$^2(2\theta _{14})$ at $\vert \Delta$m${}^{2}_{41}\vert$ $\sim{}$ $0.03$ eV${}^{2}$ (obtained from Figure 3 in AN 2016B). The exclusion curve begins at $\vert \Delta$m${}^{2}_{41}\vert \sim{}1.5 \times 10^{-4}$ eV${}^{2}$ and extends to $\sim{}0.25$ eV${}^{2}$. The analysis assumes sin$^2(2\theta _{12})$ = $0.846$ $\pm0.021$, $\Delta$m${}^{2}_{21}$ = ($7.53$ $\pm0.18$) $\times 10^{-5}$ eV${}^{2}$, and $\vert \Delta$m${}^{2}_{32}\vert$ = $0.00244$ $\pm0.00006$ eV${}^{2}$.
8  AMBROSIO 2001 tested the pure 2-flavor ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{s}}}$ hypothesis using matter effects which change the shape of the zenith-angle distribution of upward through-going muons. With maximum mixing and $\Delta$m${}^{2}$around $0.0024~$eV${}^{2}$, the ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{s}}}$ oscillation isdisfavored with 99$\%$ confidence level with respect to the ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{\tau}}}$ hypothesis.
9  FUKUDA 2000 tested the pure 2-flavor ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{s}}}$ hypothesis using three complementary atmospheric-neutrino data samples. With this hypothesis, zenith-angle distributions are expected to show characteristic behavior due to neutral currents and matter effects. In the $\Delta$m${}^{2}$ and sin$^22\theta$region preferred by the Super-Kamiokande data, the ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{s}}}$ hypothesis isrejected at the 99$\%$ confidence level, while the ${{\mathit \nu}_{{\mu}}}$ $\rightarrow$ ${{\mathit \nu}_{{\tau}}}$ hypothesis consistently fits all of the data sample.
References:
 AARTSEN 2017B
PR D95 112002 Search for Sterile Neutrino Mixing using Three Years of IceCube DeepCore Data
 ABDURASHITOV 2017
JETPL 105 753 First Measeurements in Search for keV-Sterile Neutrino in Tritium beta-Decay by Troitsk nu-Mass Experiment
 KO 2017
PRL 118 121802 Sterile Neutrino Search at the NEOS Experiment
 AARTSEN 2016
PRL 117 071801 Searches for Sterile Neutrinos with the IceCube Detector
PRL 85 3999 ${{\mathit \tau}}$ Neutrinos Favored over Sterile Neutrinos in Atmospheric Muon Neutrino Oscillations