Limits on sterile neutrino mixing using atmospheric neutrinos in Super-Kamiokande

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 .

Section: Jhep02(2016)111mentioning

confidence: 99%

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

Agarwalla

Chatterjee

Dasgupta

et al. 2016

“…A review of experimental neutrino oscillation results, interpreted in terms of |U µ4 | 2 and |U τ 4 | 2 in the range 0.1 < ∆m 2 41 < 10 eV 2 can be found in [23]; in addition, the SuperKamiokande collaboration recently published new limits based on the analysis of atmospheric neutrinos [24]. |U µ4 | 2 is constrained by muon (anti-)neutrino disappearance experi- …”

Section: Jhep06(2015)069mentioning

confidence: 99%

“…ments: CDHS [25], CCFR [26], MiniBooNE+SciBooNE [27] and MINOS [28], as well as by Super-Kamiokande [24]. Limits on |U τ 4 | 2 have been derived from the MINOS results on the neutral current interaction rate comparison between the near and the far detector [29] and more recently by the Super-Kamiokande analysis on matter effects for up-going atmospheric neutrinos [24]. As a consequence, for ∆m 2 41 > 0.1 eV 2 , the 90% CL limits are O(10 −2 ) on |U µ4 | 2 and 0.18 on |U τ 4 | 2 , the latter being dominated by the Super-Kamiokande results.…”

Section: % CLmentioning

confidence: 99%

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Agafonova¹,

Aleksandrov²,

Anokhina³

et al. 2015

Self Cite

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beamThe OPERA collaboration E-mail: alessandro.paoloni@lnf.infn.it, alessandra.pastore@ba.infn.it Abstract: The OPERA experiment, exposed to the CERN to Gran Sasso ν µ beam, collected data from 2008 to 2012. Four oscillated ν τ Charged Current interaction candidates have been detected in appearance mode, which are consistent with ν µ → ν τ oscillations at the atmospheric ∆m 2 within the "standard" three-neutrino framework. In this paper, the OPERA ν τ appearance results are used to derive limits on the mixing parameters of a massive sterile neutrino. The OPERA collaboration 11 IntroductionThe OPERA experiment [1] operated in the CERN Neutrinos to Gran Sasso (CNGS) beam produced at CERN and directed towards the Gran Sasso Underground Laboratory of INFN (LNGS), 730 km away, where the detector is located. The experiment is unique in its capability to observe ν τ appearance on an event-by-event basis. Nuclear emulsion films instrumenting the target allow the detection of the short-lived τ lepton decay, and hence the identification of ν τ Charged Current (CC) interactions. The standard three-neutrino oscillation framework predicts ν µ → ν τ oscillations with close-to-maximal mixing at the so-called atmospheric scale, ∆m 2 32 ∼ 2.4 × 10 −3 eV 2 [2], i.e. in the oscillation parameters region discovered by detecting atmospheric neutrinos [3]. OPERA has observed four ν τ CC interaction candidate events [4][5][6][7], consistent with the expectation of the standard oscillation framework at this scale. This result represents the first direct evidence of ν µ → ν τ oscillation in appearance mode.In the present paper, limits are derived on the existence of a massive sterile neutrino. The excess of ν e (ν e ) observed by the LSND [8] and MiniBooNE [9] collaborations and the so-called reactor [10] and Gallium [11,12] neutrino anomalies are also interpreted as due to the existence of a fourth sterile neutrino with mass at the eV scale. In relation to this issue, it is worth mentioning that the effective number of neutrino-like species decoupled from the primeval plasma measured by the Planck collaboration is 3.15 ± 0.23 at 95% Confidence Level (CL) [13].Neutrino oscillations at large ∆m 2 have been searched for by several short baseline experiments. The most stringent limits on ν µ → ν τ oscillations were set by the NOMAD [14] and CHORUS [15] experiments, with high sensitivity for ∆m 2 values larger than 10 eV 2 .In the following, a short description of the OPERA experimental setup and of the procedure used to detect ν τ interactions is given, the data analysis is described and exclusion regions in the parameter space are derived.

“…The lack of weak interactions of the sterile neutrino leads to a difference in the matter effects between ν µ and the linear combination of ν τ and sterile that makes up the light neutrinos. Limits on |U τ 4 | have been derived from analyzing the zenith angle distribution of muon neutrinos at Super-K [69] and in IceCube and (low energy) DeepCore data in the language of neutrino NSI [70]. The Super-K limit on |U τ 4 | is statistics limited and will be improved with more data.…”

Section: Matter Effects On Neutrino Oscillationsmentioning

confidence: 99%

“…In the presence of nonzero θ τ , ν τ N has diminished weak interactions compared to ν µ , with a potential given by V τ N = V nc cos 2 θ τ . A recent search by Super-Kamiokande [69] used atmospheric neutrinos to look for µ → sterile transitions. Because of the lack of matter effects for the sterile neutrinos, this can manifest as a change in the distribution of muon neutrino zenith angle in the detector from the standard µ → τ transition scenario.…”

Section: Jhep04(2015)170mentioning

confidence: 99%

Constraints and consequences of reducing small scale structure via large dark matter-neutrino interactions

Bertoni

Ipek

McKeen

et al. 2015

106

Cold dark matter explains a wide range of data on cosmological scales. However, there has been a steady accumulation of evidence for discrepancies between simulations and observations at scales smaller than galaxy clusters. One promising way to affect structure formation on small scales is a relatively strong coupling of dark matter to neutrinos. We construct an experimentally viable, simple, renormalizable model with new interactions between neutrinos and dark matter and provide the first discussion of how these new dark matter-neutrino interactions affect neutrino phenomenology. We show that addressing the small scale structure problems requires asymmetric dark matter with a mass that is tens of MeV. Generating a sufficiently large dark matter-neutrino coupling requires a new heavy neutrino with a mass around 100 MeV. The heavy neutrino is mostly sterile but has a substantial τ neutrino component, while the three nearly massless neutrinos are partly sterile. This model can be tested by future astrophysical, particle physics, and neutrino oscillation data. Promising signatures of this model include alterations to the neutrino energy spectrum and flavor content observed from a future nearby supernova, anomalous matter effects in neutrino oscillations, and a component of the τ neutrino with mass around 100 MeV.