Updated global 3+1 analysis of short-baseline neutrino oscillations

Abstract

We present the results of an updated fit of short-baseline neutrino oscillation data in the framework of 3+1 active-sterile neutrino mixing. We first consider ν e andν e disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactorν e spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of |U e4 | 2 . The β-decay constraints of the Mainz and Troitsk experiments allow us to limit the oscillation length between about 2 cm and 7 m at 3σ for neutrinos with an energy of 1 MeV. The corresponding oscillations can be discovered in a model-independent way in ongoing reactor and source experiments by measuring ν e andν e disappearance as a function of distance. We then consider the global fit of the data on short-baselinetransitions in the light of the LSND anomaly, taking into account the constraints from ν µ disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on |U e4 | 2 and the MINOS and IceCube constraints on |U µ4 | 2 lead to an unacceptable appearance-disappearance tension which becomes tolerable only in a pragmatic fit which neglects the MiniBooNE low-energy anomaly. The minimization of the global χ 2 in the space of the four mixing parameters Open Access, c The Authors. Article funded by SCOAP 3 .https://doi.org/10.1007/JHEP06 (2017)135 JHEP06 (2017)135 ∆m 2 41 , |U e4 | 2 , |U µ4 | 2 , and |U τ 4 | 2 leads to three allowed regions with narrow ∆m 2 41 widths at ∆m 2 41 ≈ 1.7 (best-fit), 1.3 (at 2σ), 2.4 (at 3σ) eV 2 . The effective amplitude of short-baselineν e oscillations is limited by 0.00048 sin 2 2ϑ eµ 0.0020 at 3σ. The restrictions of the allowed regions of the mixing parameters with respect to our previous global fits are mainly due to the NEOS constraints. We present a comparison of the allowed regions of the mixing parameters with the sensitivities of ongoing experiments, which show that it is likely that these experiments will determine in a definitive way if the reactor, Gallium and LSND anomalies are due to active-sterile neutrino oscillations or not.

Reactor fuel fraction information on the antineutrino anomaly

“…We use the data listed in table 1 of ref. [12] of the following experiments: Bugey-4 [13], Rovno91 [14], Bugey-3 [15], Gosgen [16], ILL [17,18], Krasnoyarsk87 [19], Krasnoyarsk94 [20,21], Rovno88 [22], SRP [23], Nucifer [24], Chooz [25], Palo Verde [26], Daya Bay [27], RENO [28], and Double Chooz [29]. The Daya Bay data in ref.…”

“…Fits of the reactor rates in table 1 of ref. [12] (without the 2016 Daya Bay rate) and the 2017 Daya Bay evolution data [11].…”

Improved determination of the U235 and Pu239<

“…[6] and V R is the covariance matrix constructed with the corresponding uncertainties. The second term in Eq.…”

“…There are two known possible explanations of the reactor antineutrino anomaly: 1) a miscalculation of one or more of the four electron antineutrino fluxes [4,5] and 2) active-sterile neutrino oscillations (see Ref. [6] and references therein). In this paper we consider the first possibility and we present an improvement of the results presented in Refs.…”

“…[6]: Bugey-4 [7], Rovno91 [8], Bugey-3 [9], Gosgen [10], ILL [11,12], Krasnoyarsk87 [13], Krasnoyarsk94 [14,15], Rovno88 [16], SRP [17], Nucifer [18], Chooz [19], Palo Verde [20], Daya Bay [21], RENO [22], and Double Chooz [23].…”