Sterile neutrinos beyond LSND at the neutrino factory

Abstract

We discuss the effects of one additional sterile neutrino at the Neutrino Factory. Compared to earlier analyses, which have been motivated by Liquid Scintillator Neutrino Detector (LSND) results, we do not impose any constraint on the additional mass squared splitting. This means that the additional mass eigenstate could, with small mixings, be located among the known ones, as it is suggested by the recent analysis of cosmological data. We use a self-consistent framework at the Neutrino Factory without any constraints on the new parameters. We demonstrate for a combined short and long baseline setup that near detectors can provide the expected sensitivity at the LSND-motivated Ám 2 41 -range, while some sensitivity can also be obtained in the region of the atmospheric mass splitting from the long baselines. We point out that limits on such very light sterile neutrinos may also be obtained from a reanalysis of atmospheric and solar neutrino oscillation data, as well as from supernova neutrino observations. In the second part of the analysis, we compare our sensitivity with the existing literature using additional assumptions, such as jÁm 2 41 j ) jÁm 2 31 j, leading to averaging of the fast oscillations in the far detectors. We demonstrate that while the Neutrino Factory has excellent sensitivity compared to existing studies using similar assumptions, one has to be very careful interpreting these results for a combined short and long baseline setup where oscillations could occur in the near detectors. We also test the impact of additional detectors at the short and long baselines, and we do not find a substantial improvement of the sensitivities.

Discovery potential of T2K and NOvA in the presence of a light sterile neutrino

“…2 Old works on sterile neutrinos at LBL can be found in [20][21][22][23][24][25][26][27][28]. More recent studies focusing on the future LBNE/DUNE experiment [29] have been recently performed in [30][31][32].…”

Interim Design Report

“…The thin red dotted curve illustrates how the sensitivity would improve if parameter correlations and degeneracies were absent, so that only statistical and systematical uncertainties would contribute. Figure taken from reference [196].…”

“…We first discuss general constraints on the new mixing angles θ 14 , θ 24 , and θ 34 , and on the additional mass squared difference ∆m 2 41 without any additional assumptions [196]. The oscillation channels considered, simulated with a modified version of the GLoBES software, are electron-to-muon neutrino oscillations (appearance channels) and muon-to-muon neutrino oscillations (disappearance channels) (see [196] for all details of the simulations).…”

“…The oscillation channels considered, simulated with a modified version of the GLoBES software, are electron-to-muon neutrino oscillations (appearance channels) and muon-to-muon neutrino oscillations (disappearance channels) (see [196] for all details of the simulations). In addition to the IDS-NF baseline setup, we have also considered near detectors with a fiducial mass of 32 Ton and a distance of d = 2 km from the end of the decay straight, which corresponds to an effective baseline of 2.28 km.…”

Common origin of reactor and sterile neutrino mixing

“…2 These parameters can be easily related to short-and long-baseline neutrino oscillation probabilities, see ref. [87] for details. To leading order in the small mixing angles, the most relevant short baseline probabilities can be written as:…”