English

Updated Global 3+1 Analysis of Short-BaseLine Neutrino Oscillations

High Energy Physics - Phenomenology 2017-08-02 v3 High Energy Physics - Experiment

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 νe\nu_e and νˉe\bar\nu_e disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor νˉe\bar\nu_e spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of Ue42|U_{e4}|^2. The beta-decay constraints allow us to limit the oscillation length between about 2 cm and 7 m at 3σ3\sigma for neutrinos with an energy of 1 MeV. We then consider the global fit of the data in the light of the LSND anomaly, taking into account the constraints from νe\nu_e and νμ\nu_\mu disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on Ue42|U_{e4}|^2 and the MINOS and IceCube constraints on Uμ42|U_{\mu4}|^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 χ2\chi^2 in the space of the four mixing parameters Δm412\Delta{m}^2_{41}, Ue42|U_{e4}|^2, Uμ42|U_{\mu4}|^2, and Uτ42|U_{\tau4}|^2 leads to three allowed regions with narrow Δm412\Delta{m}^{2}_{41} widths at Δm4121.7 \Delta m^2_{41} \approx 1.7 (best-fit), 1.3 (at 2σ2\sigma), 2.4 (at 3σ3\sigma) eV2^2. 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.

Keywords

Cite

@article{arxiv.1703.00860,
  title  = {Updated Global 3+1 Analysis of Short-BaseLine Neutrino Oscillations},
  author = {S. Gariazzo and C. Giunti and M. Laveder and Y. F. Li},
  journal= {arXiv preprint arXiv:1703.00860},
  year   = {2017}
}

Comments

39 pages; improved treatment of the reactor flux uncertainties and other minor corrections