A variety of experiments and observations limit the parameter space of a hypothetical sterile neutrino that oscillates with the three Standard Model active neutrinos but has no weak force interactions of its own. This chart (below) from the latest paper from the Double Chooz experiment, while not making much of a dent in the strong exclusions on sterile neutrino parameters established by the Daya Bay experiment, does make the evidence against sterile neutrinos more robust by largely replicating its results.
As usual: "No significant disappearance signal additionally to the conventional oscillations related to θ13 is observed and correspondingly exclusion bounds on the sterile mixing parameter θ14 as function
of ∆m^2
41 are obtained."
Y-axis shows the square of the difference between the lightest neutrino mass and the the sterile neutrino mass. The top of the chart corresponds to a fourth generation neutrino mass of approximately 0.548 eV (about 1 millionth the mass of the electron). The bottom of the chart corresponds to a fourth generation neutrino mass of approximately 0.007 eV (about the same as the second generation neutrino mass).
The X-axis shows a function of the mixing angles of the electron neutrino and the fourth sterile neutrino species.
Sin^2 (2theta(14))=0.1 corresponds to a mixing angle of about 9.2º.
Sin^2 (2theta(14))=0.005 corresponds to a mixing angle of about 2º.
For comparison's sake, the best experimentally determined fits to the existing neutrino mixing angles (as of 2018) are:
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