Status of light sterile neutrino searches

Abstract

A number of anomalous results in short-baseline oscillation may hint at the existence of one or more light sterile neutrino states in the eV mass range and have triggered a wave of new experimental efforts to search for a definite signature of oscillations between active and sterile neutrino states. The present paper aims to provide a comprehensive review on the status of light sterile neutrino searches in mid-2019: we discuss not only the basic experimental approaches and sensitivities of reactor, source, atmospheric, and accelerator neutrino oscillation experiments but also the complementary bounds arising from direct neutrino mass experiments and cosmological observations. Moreover, we review current results from global oscillation analyses that include the constraints set by running reactor and atmospheric neutrino experiments. They permit to set tighter bounds on the active-sterile oscillation parameters but as yet are not able to provide a definite conclusion on the existence of eV-scale sterile neutrinos.

Physics potential of ESSνSB in the presence of a light sterile neutrino

“…4 give rise to a unique connected region. 6 To simulate the DUNE setup, we consider the reference design as mentioned in the Conceptual Design Report (CDR) [15] and the necessary simulation files for the GLoBES software are taken from [58]. 7 To estimate the reconstruction capability of the T2HK setup, we closely follow the experimental configurations as described in Ref.…”

“…Several anomalous results recorded in short-baseline (SBL) experiments, indicate the existence of a fourth sterile neutrino (for a review on this subject, see the references [1][2][3][4][5][6]) with mass ∼ 1 eV. New SBL experiments are under construction, with the aim of testing this intriguing hypothesis (see the review in [7]).…”

Sterile neutrinos with altered dispersion relations revisited

“…For current reviews on this topic see Refs. [21,22]. It has been shown that adding simply more sterile neutrinos will not resolve this tension either [23].…”

Sensitivity to light sterile neutrinos at ESSnuSB

“…(2.9), the relative sign between the phases are different compared to Refs. [4,22], since we have used a different convention for the sterile CP-violating phases.…”

“…However, they can mix with the active neutrinos and therefore take part in the oscillation phenomenon. Recently, there are compelling experimental evidences towards the existence of a light sterile neutrino at the eV scale [4]. For a review on this subject, we refer to Ref.…”