Nonmaximal θ23 Mixing at NOvA from Neutrino Decoherence

Abstract

In a study of a muon-neutrino disappearance at 810 km, the NOvA experiment finds flavor mixing of the atmospheric sector to deviate from maximal (sin^{2}θ_{23}=0.5) by 2.6σ. The result is in tension with the 295-km baseline measurements of T2K, which are consistent with maximal mixing. We propose that θ_{23} is in fact maximal, and that the disagreement is a harbinger of environmentally induced decoherence. The departure from maximal mixing can be accounted for by an energy-independent decoherence of strength Γ=(2.3±1.1)×10^{-23} GeV.

Decoherence in neutrino propagation through matter, and bounds from IceCube/DeepCore

“…[13,14] a solution to the LSND anomaly based on quantum decoherence, compatible with global neutrino oscillation data, was proposed. More recently, in [17] it was shown that the ∼ 2σ tension between T2K and NOvA on the measurement of the atmospheric mixing angle θ 23 could be alleviated through the inclusion of decoherence effects in the atmospheric neutrino sector, namely, γ 23 = (2.3 ± 1.1) · 10 −23 GeV. Such value of γ 23 would be close to the SK bound from ref.…”

“…In particular, we find that the reference value for γ 23 considered in ref. [17] to explain the small tension previously reported between NOvA and SK data is indeed already excluded by IceCube data. Regarding the cases with n = 1, 2, we find that the sensitivity of IceCube is particularly strong.…”

“…[16,18,19]. In this work we will show that the reference value for γ 23 considered in [17] is indeed already excluded by IceCube data (we note however that, according to the latest results reported by NOvA, the significance of the tension has been reduced to less than 1σ [3]). Moreover, we find that Ice-Cube and DeepCore data are able to improve significantly over most of the constraints in past literature, both for solar and atmospheric decoherence parameters, in some cases by several orders of magnitude.…”

“…In this work we study one of the possible windows to NP, the so-called quantum decoherence in neutrino oscillations, and update the existing bounds by analyzing IceCube and DeepCore data on atmospheric neutrinos. In particular, we are interested in a kind of decoherence effects in neutrino oscillations studied, for example, in [6][7][8][9][10][11][12][13] and, more recently, in [14][15][16][17][18][19]. These decoherence effects differ from the standard decoherence caused by the separation of wave packets (see e.g.…”

Muon-Neutrino Electron Elastic Scattering and a Search for the Muon-Neutrino Magnetic Moment in the NOvA Near Detector

“…But there are two many nuisance parameters in this issue. The angular K + production parameter [73], the non-standard interaction effects [40,86] and the unknown ν e interference might all count.…”