Non-standard Hamiltonian effects on neutrino oscillations

Abstract

We investigate non-standard Hamiltonian effects on neutrino oscillations, which are effective additional contributions to the vacuum or matter Hamiltonian. Since these effects can enter in either flavor or mass basis, we develop an understanding of the difference between these bases representing the underlying theoretical model. In particular, the simplest of these effects are classified as "pure" flavor or mass effects, where the appearance of such a "pure" effect can be quite plausible as a leading non-standard contribution from theoretical models. Compared to earlier studies investigating particular effects, we aim for a topdown classification of a possible "new physics" signature at future long-baseline neutrino oscillation precision experiments. We develop a general framework for such effects with two neutrino flavors and discuss the extension to three neutrino flavors, as well as we demonstrate the challenges for a neutrino factory to distinguish the theoretical origin of these effects with a numerical example. We find how the precision measurement of neutrino oscillation parameters can be altered by non-standard effects alone (not including nonstandard interactions in the creation and detection processes) and that the non-standard effects on Hamiltonian level can be distinguished from other non-standard effects (such as neutrino decoherence and decay) if we consider specific imprint of the effects on the energy spectra of several different oscillation channels at a neutrino factory.

Effects of nonstandard neutrino interactions at PINGU

“…Namely, the resonance has been shifted by the NSI parameter, which has also been pointed out in Ref. [30] in the framework of two-neutrino oscillations. For a fixed value of θ 13 , if ε µτ becomes larger, the neutrino energy has to increase in order to balance the negative contribution from ε µτ .…”

Interpretation of MINOS data in terms of nonstandard neutrino interactions

“…The modifications to the far detector event spectra observed in MINOS can be induced by (i) operators leading to a modified flux of ν µ at the far detector, but not at the near detector, and (ii) by operators leading to the production of muons in interactions of ν τ . (We neglect the possibility of non-standard interactions of ν e since their flux at the far detector is between one and two order of magnitude smaller than that of ν µ because of the low ν e contamination of the NuMI beam and the smallness of the mixing angle θ 13 .) The only way of realizing case (i) in a three-flavor framework is to postulate a ν τ contamination in the NuMI beam, which would be invisible to the near detector, but would have partly oscillated into ν µ when reaching the far detector.…”

“…Many authors have in-vestigated the phenomenology of such subdominant NSI, both model-independently [10][11][12][13][14][15] and in concrete models [7,10,[16][17][18][19][20][21][22][23][24]. In particular, NSI have been considered in the context of solar neutrino observations [6,9,10,[25][26][27][28][29][30][31], reactor neutrino experiments [32], atmospheric neutrinos [33][34][35][36][37][38][39], conventional and upgraded neutrino beams [36,38,[40][41][42][43][44][45][46][47][48][49], neutrino factories [13,41,…”

Dark energy and neutrino CPT-violation

“…Recently there have been a lot of interests in the literature [17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32] in studying the possible interactions between the neutrinos and the dark energy. An interesting prediction of these models is that the neutrino masses are not constant, but vary as a function of time and space [18,19].…”