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

Abstract

Abstract:We study the impact of one light sterile neutrino on the prospective data expected to come from the two presently running long-baseline experiments T2K and NOνA when they will accumulate their full planned exposure. Introducing for the first time, the bi-probability representation in the 4-flavor framework, commonly used in the 3-flavor scenario, we present a detailed discussion of the behavior of the ν µ → ν e andν µ →ν e transition probabilities in the 3+1 scheme. We also perform a detailed sensitivity study of these two experiments (both in the stand-alone and combined modes) to assess their discovery reach in the presence of a light sterile neutrino. For realistic benchmark values of the mass-mixing parameters (as inferred from the existing global short-baseline fits), we find that the performance of both these experiments in claiming the discovery of the CP-violation induced by the standard CP-phase δ 13 ≡ δ, and the neutrino mass hierarchy get substantially deteriorated. The exact loss of sensitivity depends on the value of the unknown CP-phase δ 14 . Finally, we estimate the discovery potential of total CP-violation (i.e., induced simultaneously by the two CP-phases δ 13 and δ 14 ), and the capability of the two experiments of reconstructing the true values of such CP-phases. The typical (1σ level) uncertainties on the reconstructed phases are approximately 40 0 for δ 13 and 50 0 for δ 14 .

A hybrid setup for fundamental unknowns in neutrino oscillations using T2HK (ν) and μ-DAR ν ¯ $$ \left(\overline{\nu}\right) $$

“…assuming θ 23 to be maximal [22][23][24][25][26][27][28][29]. Under the same conditions, these experiments can reject the wrong hierarchy at ∼ 3.4σ confidence level.…”

Capabilities of long-baseline experiments in the presence of a sterile neutrino

“…Additionally, [43] has analysed the sensitivity of the experiment now known as DUNE to two sterile neutrinos whose physics is described by a minimal 3+2 model. Recently, in [44] the long-baseline effects of one sterile neutrino have been studied, and sensitivity calculations in the presence of such a neutrino have been presented in [45,46].…”

“…In other words, it translates and extends, to the level of sensitivities, this important physics point regarding the effect of matter made earlier in [27], which demonstrated it at the level of probabilities and event rates. In [45,46], the authors try to determine the potential of T2K, NOνA and DUNE to distinguish a CP-violating value of a given CP phase δ x from a situation where the same phase δ x has been assumed to be CP conserving while leaving the other two phases free. In contrast to this, we determine the potential of the long-baseline experiments to distinguish between the situation where any one or more of the CP phases has a CP-violating value, and the situation where all the CP phases have CP-conserving values.…”

Can we probe intrinsic CP and T violations and nonunitarity at long baseline accelerator experiments?

“…Going beyond the recent studies revealing how potential new physics scenarios can hinder the clean determination of this important parameter [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34], we address the issue of clean separation of the intrinsic leptonic CP phase from the extrinsic contribution arising due to SI as well as new physics 7 . We also show the impact of new physics on testing non-unitarity.…”

“…We also probe deviations due to new physics scenarios. We go beyond the SM in two respects -one in which we introduce subdominant effects due to a possible source of new physics dubbed as NSI [17][18][19][20][21][22][23][24][25][26] and another where the presence of extra sterile state can lead to non-unitarity in the 3×3 part even though the overall mixing matrix is still unitary [27][28][29][30][31][32][33][34] and examine consequences relevant to long baseline experiments (For other new physics scenarios such as non-unitarity, see [35][36][37][38][39]). We highlight the regions in L − E space where the effects due to CP and T violation are drastically modified due to new physics.…”