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ANTARES Collaboration(Adrian-Martinez, S. et al), Bigongiari, C., Dornic, D., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., et al. (2012). Measurement of atmospheric neutrino oscillations with the ANTARES neutrino telescope. Phys. Lett. B, 714(2-5), 224–230.
Abstract: The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximal mixing, a mass difference of Delta m(32)(2) = (3.1 +/- 0.9) . 10(-3) eV(2) is obtained, in good agreement with the world average value.
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Leitner, R., Malinsky, M., Roskovec, B., & Zhang, H. (2011). Non-standard antineutrino interactions at Daya Bay. J. High Energy Phys., 12(12), 001–26pp.
Abstract: We study the prospects of pinning down the effects of non-standard antineutrino interactions in the source and in the detector at the Daya Bay neutrino facility. It is well known that if the non-standard interactions in the detection process are of the same type as those in the production, their net effect can be subsumed into a mere shift in the measured value of the leptonic mixing angle theta(13). Relaxing this assumption, the ratio of the antineutrino spectra measured by the Daya Bay far and near detectors is distorted in a characteristic way, and good fits based on the standard oscillation hypothesis are no longer viable. We show that, under certain conditions, three years of Daya Bay running can be sufficient to provide a clear hint of non-standard neutrino physics.
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Donini, A., Hernandez, P., Lopez-Pavon, J., Maltoni, M., & Schwetz, T. (2012). The minimal 3+2 neutrino model versus oscillation anomalies. J. High Energy Phys., 07(7), 161–20pp.
Abstract: We study the constraints imposed by neutrino oscillation experiments on the minimal extension of the Standard Model that can explain neutrino masses, which requires the addition of just two singlet Weyl fermions. The most general renormalizable couplings of this model imply generically four massive neutrino mass eigenstates while one remains massless: it is therefore a minimal 3+2 model. The possibility to account for the confirmed solar, atmospheric and long-baseline oscillations, together with the LSND/MiniBooNE and reactor anomalies is addressed. We find that the minimal model can fit oscillation data including the anomalies better than the standard 3 nu model and similarly to the 3 + 2 phenomenological models, even though the number of free parameters is much smaller than in the latter. Accounting for the anomalies in the minimal model favours a normal hierarchy of the light states and requires a large reactor angle, in agreement with recent measurements. Our analysis of the model employs a new parametrization of seesaw models that extends the Casas-Ibarra one to regimes where higher order corrections in the light-heavy mixings are significant.
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Agarwalla, S. K., & Hernandez, P. (2012). Probing the neutrino mass hierarchy with Super-Kamiokande. J. High Energy Phys., 10(10), 086–14pp.
Abstract: We show that for recently discovered large values of theta(13), a superbeam with an average neutrino energy of similar to 5 GeV, such as those being proposed at CERN, if pointing to Super-Kamiokande (L similar or equal to 8770 km), could reveal the neutrino mass hierarchy at 5 sigma in less than two years irrespective of the true hierarchy and CP phase. The measurement relies on the near resonant matter effect in the nu(mu) -> nu(e) oscillation channel, and can be done counting the total number of appearance events with just a neutrino beam.
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Agarwalla, S. K., Bagchi, P., Forero, D. V., & Tortola, M. (2015). Probing non-standard interactions at Daya Bay. J. High Energy Phys., 07(7), 060–33pp.
Abstract: In this article we consider the presence of neutrino non-standard interactions (NSI) in the production and detection processes of reactor antineutrinos at the Daya Bay experiment. We report for the first time, the new constraints on the flavor non-universal and flavor universal charged-current NSI parameters, estimated using the currently released 621 days of Daya Bay data. New limits are placed assuming that the new physics effects are just inverse of each other in the production and detection processes. With this special choice of the NSI parameters, we observe a shift in the oscillation amplitude without distorting the L/E pattern of the oscillation probability. This shift in the depth of the oscillation dip can be caused by the NSI parameters as well as by theta(13), making it quite difficult to disentangle the NSI effects from the standard oscillations. We explore the correlations between the NSI parameters and theta(13) that may lead to significant deviations in the reported value of the reactor mixing angle with the help of iso-probability surface plots. Finally, we present the limits on electron, muon/tau, and flavor universal (FU) NSI couplings with and without considering the uncertainty in the normalization of the total event rates. Assuming a perfect knowledge of the event rates normalization, we find strong upper bounds similar to 0.1% for the electron and FU cases improving the present limits by one order of magnitude. However, for a conservative error of 5% in the total normalization, these constraints are relaxed by almost one order of magnitude.
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Gariazzo, S., Giunti, C., Laveder, M., & Li, Y. F. (2017). Updated global 3+1 analysis of short-baseline neutrino oscillations. J. High Energy Phys., 06(6), 135–38pp.
Abstract: We present the results of an updated fit of short-baseline neutrino oscillation data in the framework of 3+1 active-sterile neutrino mixing. We first consider v(e) and (v) over bar (e) disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor (v) over bar (e) spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of |U-e1|(2). The beta-decay constraints of the Mainz and Troitsk experiments allow us to limit the oscillation length between about 2 cm and 7 m at 3 sigma for neutrinos with an energy of 1 MeV. The corresponding oscillations can be discovered in a model-independent way in ongoing reactor and source experiments by measuring v(e) and (v) over bar (e), disappearance as a function of distance. We then consider the global fit of the data on short-baseline v(mu)((-)) -> v(e)((-)) transitions in the light of the LSND anomaly, taking into account the constraints from v(e)(( )) and v(mu)((-)) disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on |U-e4|(2) and the MINOS and IceCube constraints on |U-mu 4|(2) lead to an unacceptable appearance-disappearance tension which becomes tolerable only in a pragmatic fit which neglects the MiniBooNE low-energy anomaly. The minimization of the global chi(2) in the space of the four mixing parameters Delta m(41)(2), |U-e4|(2), |U-mu 4|(2) and |U-4 tau|(2) leads to three allowed regions with narrow Delta m(41)(2) widths at Delta m(41)(2) approximate to 1.7 (best-fit), 1.3 (at 2 sigma), 2.4 (at 3 sigma) eV(2). The effective amplitude of short-baseline v(mu)((-)) -> v(e)((-)) oscillations is limited by 0.00048 less than or similar to sin(2) 2 nu(e mu) less than or similar to 0.0020 at 3 sigma The restrictions of the allowed regions of the mixing parameters with respect to our previous global fits are mainly due to the NEOS constraints. We present a comparison of the allowed regions of the mixing parameters with the sensitivities of ongoing experiments, which show that it is likely that these experiments will determine in a definitive way if the reactor, Gallium and LSND anomalies are due to active-sterile neutrino oscillations or not.
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Rocha-Moran, P., & Vicente, A. (2016). Lepton Flavor Violation in the singlet-triplet scotogenic model. J. High Energy Phys., 07(7), 078–25pp.
Abstract: We investigate lepton flavor violation (LFV) in the the singlet-triplet scotogenic model in which neutrinos acquire non-zero masses at the 1-loop level. In contrast to the most popular variant of this setup, the singlet scotogenic model, this version includes a triplet fermion as well as a triplet scalar, leading to a scenario with a richer dark matter phenomenology. Taking into account results from neutrino oscillation experiments, we explore some aspects of the LFV phenomenology of the model. In particular, we study the relative weight of the dipole operators with respect to other contributions to the LFV amplitudes and determine the most constraining observables. We show that in large portions of the parameter space, the most promising experimental perspectives are found for LFV 3-body decays and for coherent mu-e conversion in nuclei.
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Thakore, T., Devi, M. M., Agarwalla, S. K., & Dighe, A. (2018). Active-sterile neutrino oscillations at INO-ICAL over a wide mass-squared range. J. High Energy Phys., 08(8), 022–34pp.
Abstract: We perform a detailed analysis for the prospects of detecting active-sterile oscillations involving a light sterile neutrino, over a large Delta m(41)(2 )range of 10(-5) eV(2) to 10(2) eV(2), using 10 years of atmospheric neutrino data expected from the proposed 50 kt magnetized ICAL detector at the INO. This detector can observe the atmospheric nu(mu), and (nu) over bar (mu) separately over a wide range of energies and baselines, making it sensitive to the magnitude and sign of Arni i over a large range. If there is no light sterile neutrino, ICAL can place competitive upper limit on vertical bar U-mu 4 vertical bar(2) less than or similar to 0.02 at 90% C.L. for Delta m(41)(2) in the range (0.5-5) x 10(-3) eV(2). For the same vertical bar Delta m(41)(2)vertical bar range, ICAL would be able to determine its sign, exploiting the Earth's matter effect in mu(-) and mu(+) events separately if there is indeed a light sterile neutrino in Nature. This would help identify the neutrino mass ordering in the four-neutrino mixing scenario.
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Biggio, C., Fernandez-Martinez, E., Filaci, M., Hernandez-Garcia, J., & Lopez-Pavon, J. (2020). Global bounds on the Type-III Seesaw. J. High Energy Phys., 05(5), 022–33pp.
Abstract: We derive general bounds on the Type-III Seesaw parameters from a global fit to flavor and electroweak precision data. We explore and compare three Type-III Seesaw realizations: a general scenario, where an arbitrary number of heavy triplets is integrated out without any further assumption, and the more constrained cases in which only 3 or 2 (minimal scenario) additional heavy states are included. The latter assumption implies rather non-trivial correlations in the Yukawa flavor structure of the model so as to reproduce the neutrino masses and mixings as measured in neutrino oscillations experiments and thus qualitative differences can be found with the more general scenario. In particular, we find that, while the bounds on most elements of the dimension 6 operator coefficients are of order 10(-4) for the general and 3-triplet cases, the 2-triplet scenario is more strongly constrained with bounds between 10(-5) and 10(-7) for the different flavours. We also discuss how these correlations affect the present CMS constraints on the Type-III Seesaw in the minimal 2-triplet scenario.
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de Gouvea, A., De Romeri, V., & Ternes, C. A. (2020). Probing neutrino quantum decoherence at reactor experiments. J. High Energy Phys., 08(8), 049–17pp.
Abstract: We explore how well reactor antineutrino experiments can constrain or measure the loss of quantum coherence in neutrino oscillations. We assume that decoherence effects are encoded in the size of the neutrino wave-packet, sigma. We find that the current experiments Daya Bay and the Reactor Experiment for Neutrino Oscillation (RENO) already constrain sigma >1.0x10(-4) nm and estimate that future data from the Jiangmen Underground Neutrino Observatory (JUNO) would be sensitive to sigma <2.1x10(-3) nm. If the effects of loss of coherence are within the sensitivity of JUNO, we expect sigma to be measured with good precision. The discovery of nontrivial decoherence effects in JUNO would indicate that our understanding of the coherence of neutrino sources is, at least, incomplete.
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