Non-Unitarity vs sterile neutrinos at DUNE

Neutrino masses are one of the most promising open windows to physics beyond the Standard Model (SM). Several extensions of the SM which accommodate neutrino masses require the addition of right-handed neutrinos to its particle content. These extra fermions will either be kinematically accessible (sterile neutrinos) or not (deviations from Unitarity of the PMNS matrix) but at some point they will impact neutrino oscillation searches. We explore the differences and similitudes between the two cases and compare their present bounds with the expected sensitivities of DUNE. We conclude that Non-Unitarity (NU) effects are too constrained to impact present or near future neutrino oscillation facilities but that sterile neutrinos can play an important role at long baseline experiments.Comment: Talk and poster presented at NuPhys2016 (London, 12-14 December 2016). 8 pages, LaTeX, 4 eps figures. Based on arXiv:1609.0863

On neutrinoless double beta decay in the minimal left-right symmetric model

We analyze the general phenomenology of neutrinoless double beta decay in the minimal left-right symmetric model. We study under which conditions a New Physics dominated neutrinoless double beta decay signal can be expected in the future experiments. We show that the correlation among the different contributions to the process, which arises from the neutrino mass generation mechanism, can play a crucial role. We have found that, if no fine tuned cancellation is involved in the light active neutrino contribution, a New Physics signal can be expected mainly from the $W_R-W_R$ channel. An interesting exception is the $W_L-W_R$ channel which can give a dominant contribution to the process if the right-handed neutrino spectrum is hierarchical with $M_1\lesssim$ MeV and $M_2,M_3\gtrsim$ GeV. We also discuss if a New Physics signal in neutrinoless double beta decay experiments is compatible with the existence of a successful Dark Matter candidate in the left-right symmetric models. It turns out that, although it is not a generic feature of the theory, it is still possible to accommodate such a signal with a KeV sterile neutrino as Dark matter.Comment: 33 pages, 6 figures, references and complementary constraints added, version accepted by European Physical Journal

The seesaw portal in testable models of neutrino masses

A Standard Model extension with two Majorana neutrinos can explain the measured neutrino masses and mixings, and also account for the matter-antimatter asymmetry in a region of parameter space that could be testable in future experiments. The testability of the model relies to some extent on its minimality. In this paper we address the possibility that the model might be extended by extra generic new physics which we parametrize in terms of a low-energy effective theory. We consider the effects of the operators of the lowest dimensionality, $d=5$, and evaluate the upper bounds on the coefficients so that the predictions of the minimal model are robust. One of the operators gives a new production mechanism for the heavy neutrinos at LHC via higgs decays. The higgs can decay to a pair of such neutrinos that, being long-lived, leave a powerful signal of two displaced vertices. We estimate the LHC reach to this process.Comment: 19 pages, 11 figure

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

We revisit neutrino oscillations in matter considering the open quantum system framework which allows to introduce possible decoherence effects generated by New Physics in a phenomenological manner. We assume that the decoherence parameters $\gamma_{ij}$ may depend on the neutrino energy, as $\gamma_{ij}=\gamma_{ij}^{0}(E/\text{GeV})^n$ $(n = 0,\pm1,\pm2)$. The case of non-uniform matter is studied in detail, both within the adiabatic approximation and in the more general non-adiabatic case. In particular, we develop a consistent formalism to study the non-adiabatic case dividing the matter profile into an arbitrary number of layers of constant densities. This formalism is then applied to explore the sensitivity of IceCube and DeepCore to this type of effects. Our study is the first atmospheric neutrino analysis where a consistent treatment of the matter effects in the three-neutrino case is performed in presence of decoherence. We show that matter effects are indeed extremely relevant in this context. We find that IceCube is able to considerably improve over current bounds in the solar sector ($\gamma_{21}$) and in the atmospheric sector ($\gamma_{31}$ and $\gamma_{32}$) for $n=0,1,2$ and, in particular, by several orders of magnitude (between 3 and 9) for the $n=1,2$ cases. For $n=0$ we find $\gamma_{32},\gamma_{31}< 4.0\cdot10^{-24} (1.3\cdot10^{-24})$ GeV and $\gamma_{21}<1.3\cdot10^{-24} (4.1\cdot10^{-24})$ GeV, for normal (inverted) mass ordering.Comment: 31 pages, 8 figure

The seesaw path to leptonic CP violation

Future experiments such as SHiP and high-intensity $e^+ e^-$ colliders will have a superb sensitivity to heavy Majorana neutrinos with masses below $M_Z$. We show that the measurement of the mixing to electrons and muons of one such state could imply the discovery of leptonic CP violation in the context of seesaw models. We quantify in the minimal model the CP discovery potential of these future experiments, and demonstrate that a 5$\sigma$ CL discovery of leptonic CP violation would be possible in a very significant fraction of parameter space.Comment: An error has been fixed, main conclusions unchange