Constraining sterile neutrino cosmology with terrestrial oscillation experiments

Abstract

We explore the complementarity between terrestrial neutrino oscillation experiments and astrophysical/cosmological measurements in probing the existence of sterile neutrinos. We find that upcoming accelerator neutrino experiments will not improve on constraints by the time they are operational, but that reactor experiments can already probe parameter space beyond the reach of Planck. We emphasize the tension between cosmological experiments and reactor antineutrino experiments and enumerate several possibilities for resolving this tension. † It is, by hypothesis, not possible to directly detect sterile neu-arXiv:1905.03254v1 [hep-ph]

Thermalisation of sterile neutrinos in the early universe in the 3+1 scheme with full mixing matrix

“…f (y) = [exp(y/w s ) + 1] −1 , where w s ≡ T s a = (T s /T ν ) w and T s /T ν = ∆N 1/4 eff (see e.g. [28,30,31,50,51]). Thus, we show that this latter possibility, denoted as thermal distribution, is inaccurate to study the 3+1 sterile neutrino case, for which we find that the DW approximation is excellent.…”

“…Note that the blue curve is not 4 Since we consider the sterile neutrino in a 3+1 scheme, we restrict ourselves to the case m4 > m3 (normal ordering) or m4 > m2 (inverted ordering), i.e. ∆m 2 41 > ∆m 2 31 2.5 × 10 −3 eV 2 and ∆m 2 41 > ∆m 2 21 7.5 × 10 −5 eV 2 , respectively. Thus, the new squared mass difference does not significantly alter the oscillations of the three active neutrinos.…”

“…The quantum kinetic equations were solved with a modified version of the LASAGNA code [27], enforcing a zero lepton asymmetry. The same code has been used in later works [28][29][30][31] to convert the active-sterile mixing parameters into two other quantities relevant for cosmology (N eff and the effective sterile neutrino mass m s eff ), in order to obtain bounds from Planck data and from current and future neutrino oscillation experiments in the framework of the two-neutrino approximation (either ν e -ν s or ν µ -ν s mixing).…”

Recent Probes of Standard and Non-standard Neutrino Physics With Nuclei

“…Finally, focusing at CONUS in Ref. [150] it was shown that the complementarity between terrestrial-cosmological experiments may resolve the tension raised by astrophysical observations regarding the existence of sterile neutrinos.…”

Probing new neutral gauge bosons with CEνNS and neutrino-electron scattering

“…[25]). New constraints have been placed on non-standard and generalized interactions [26][27][28][29], nuclear physics parameters [30][31][32], neutrino electromagnetic properties [33,34] and sterile neutrinos [35][36][37]. It has been noted [38][39][40][41][42][43][44][45][46] that light mediators may be accessible to CEνNS experiments, providing information that is complementary to what can be achieved from high-energy and/or precision measurements.…”