First Constraints on the Complete Neutrino Mixing Matrix with a Sterile Neutrino

“…Current global fits of the neutrino oscillations experimental data suggest jU e4 j 2 ¼ 0.023-0.028, where the range covers values presented in [33,[68][69][70]. In this study jU e4 j 2 is assumed to be zero.…”

Section: Discussionmentioning

confidence: 77%

Search for sterile neutrino mixing using three years of IceCube DeepCore data

Aartsen¹,

Meagher²,

Schoenen³

et al. 2017

Phys. Rev. D

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128

165

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We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately 10-60 GeV. DeepCore is the low-energy subarray of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light (Δm 2 41 ∼ 1 eV 2 ) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction and, therefore, cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three-neutrino hypothesis. Therefore, we derive limits on the mixing matrix elements at the level of jU μ4 j 2 < 0.11 and jU τ4 j 2 < 0.15 (90% C.L.) for the sterile neutrino mass splitting Δm 2 41 ¼ 1.0 eV 2 .

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“…The new upper limit from the IceCube Collaboration [63] on sin 2 2θ 24 around the current best-fit ∆m 2 41 1.75 eV 2 [66] is 0.2 at 99% confidence level, which means that θ 24 is constrained to be smaller than 13…”

Section: Note Addedmentioning

confidence: 91%

Octant of θ23 in Danger with a Light Sterile Neutrino

2017

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Present global fits of world neutrino data hint towards non-maximal θ23 with two nearly degenerate solutions, one in the lower octant (θ23 < π/4), and the other in the higher octant (θ23 > π/4). This octant ambiguity of θ23 is one of the fundamental issues in the neutrino sector, and its resolution is a crucial goal of next-generation long-baseline (LBL) experiments. In this letter, we address for the first time, the impact of a light eV-scale sterile neutrino towards such a measurement, taking the Deep Underground Neutrino Experiment (DUNE) as a case study. In the so-called 3+1 scheme involving three active and one sterile neutrinos, the νµ → νe transition probability probed in the LBL experiments acquires a new interference term via active-sterile oscillations. We find that this interference term can mimic a swap of the θ23 octant, even if one uses the information from both neutrino and antineutrino channels. As a consequence, the sensitivity to the octant of θ23 can be completely lost, and this may have serious implications for our understanding of neutrinos from both the experimental and theoretical perspectives.

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First Constraints on the Complete Neutrino Mixing Matrix with a Sterile Neutrino

Cited by 82 publications

References 73 publications

Sterile neutrino mixing now and in the next 10+ years

Sterile neutrino mixing now and in the next 10+ years

Search for sterile neutrino mixing using three years of IceCube DeepCore data

Octant of θ23 in Danger with a Light Sterile Neutrino

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