Related papers: Limits on Neutrino Mixing with new Heavy Particles
We revise the bounds on heavy sterile neutrinos, especially in the case of their mixing with muon neutrinos in the charged current. We summarize the present experimental limits, and we reanalyze the existing data from the accelerator…
Motivated by the recent search for a Higgs-Portal Scalar decaying inside the MicroBooNE detector, we demonstrate that the same search can be used to constrain Heavy Neutral Leptons. These are gauge-singlet fermions that interact with the…
The small neutrino mass observed in neutrino oscillations is nicely explained by the seesaw mechanism. Rich phenomenology is generally expected if the heavy neutrinos are not much heavier than the electroweak scale. A model with this…
The experimental rate of neutrinoless double beta decay can be saturated by the exchange of virtual sterile neutrinos, that mix with the ordinary neutrinos and are heavier than 200 MeV. Interestingly, this hypothesis is subject only to…
This talk summarizes our recent work which studied the impact of resonant neutrino conversion induced by some non-standard neutrino properties beyond mass and mixing, such as neutrino magnetic moment, lepton-flavor non-universality as well…
We present an updated and improved global fit analysis of precision and flavor observables so as to derive constraints on deviations from unitarity in the leptonic mixing matrix. We focus on the case in which these deviations are sourced by…
We suggest an approach to explain the observed pattern of the neutrino masses and mixing which employs the weakly broken quark-lepton symmetry and does not require introduction of an ad hoc symmetry of the neutrino sector. The mass matrices…
Sterile neutrinos can be produced through mixing with active neutrinos in the hot, dense core of a core-collapse supernova (SN). The standard bounds on the active-sterile mixing ($\sin^2 \theta$) from SN arise from SN1987A energy-loss,…
Lepton mixing can originate from the breaking of a flavor symmetry in different ways in the neutrino and the charged lepton sector. We propose an extension of this framework which allows to connect the mixing parameters with masses, and…
We consider nonstandard interactions of neutrinos with electrons arising from a new light spin-1 particle with mass of tens of GeV or lower and couplings to the neutrinos and electron. This boson is not necessarily a gauge boson and is…
Whether the neutrino mass spectrum is normal (m_1 < m_2 < m_3) or abnormal (m_3 < m_1 < m_2) remains an open question, but we show that the latter possibility looks quite unnatural when it is related to the lepton flavor mixing matrix U in…
Discovering neutrino decay would be strong evidence of physics beyond the Standard Model. Presently, there are only lax lower limits on the lifetime $\tau$ of neutrinos, of $\tau/m \sim 10^{-3}$ s eV$^{-1}$ or worse, where $m$ is the…
We present a simple scheme of mixing of four neutrinos that can accommodate the results of all neutrino oscillation experiments, the observed abundances of primordial elements and the current upper bound for the effective Majorana neutrino…
In the type-I seesaw mechanism, both the light Majorana neutrinos (\nu_1, \nu_2, \nu_3) and the heavy Majorana neutrinos (N_1, ..., N_n) can mediate the neutrinoless double-beta (0\nu\beta\beta) decay. We point out that the contribution of…
Neutrinoless double beta decay is a sensitive probe of the patterns of neutrino masses and mixings if the neutrinos are Majorana particles as well as other new physics scenarios beyond the standard model. In this talk, the present…
A Majorana mass term for the $\tau$ neutrino would induce neutrino - antineutrino mixing and thereby a process which violates fermion number by two units. We study the possibility of distinguishing between a massive Majorana and a Dirac…
Several models of neutrino masses predict the existence of neutral heavy leptons. Here, we review current constraints on heavy neutrinos and apply a new formalism separating new physics from Standard Model. We discuss also the indirect…
In the limit of an approximate $\mu-\tau$ symmetry in the neutrino mass matrix, we explore deviations to the Tri-Bi-Maximal mixing pattern in the neutrino sector. We consider two different ansatzes for the corrected pattern to predict the…
Stopped muons, which are generic in pion-at-rest experiments, can shed light on heavy neutral leptons (HNLs) in unexplored parameter spaces. If the HNL is lighter than the muon, the HNL can be produced from decays of muons and pions.The HNL…
We propose simple phenomenological lepton mass matrices which describe the three neutrinos almost degenerate in mass, leading to a very large mixing angle between $\nu_\mu$ and $\nu_\tau$, as consistent with a recent report on atmospheric…