Search results for "Seesaw molecular geometry"
showing 9 items of 89 documents
Universality-Breaking Effects in Leptonic Z Decays
1993
We analyze the possibility of universality violation in diagonal leptonic decays of the $Z$ boson, in the context of interfamily "see-saw" models. In a minimal extension of the Standard Model with right-handed neutrino fields, we find that universality-breaking effects increase quadratically with the heavy Majorana neutrino mass and may be observed in the running $LEP$ experiments.
Nonunitary neutrino mixing in short and long-baseline experiments
2021
Non-unitary neutrino mixing in the light neutrino sector is a direct consequence of type-I seesaw neutrino mass models. In these models, light neutrino mixing is described by a sub-matrix of the full lepton mixing matrix and, then, it is not unitary in general. In consequence, neutrino oscillations are characterized by additional parameters, including new sources of CP violation. Here we perform a combined analysis of short and long-baseline neutrino oscillation data in this extended mixing scenario. We did not find a significant deviation from unitary mixing, and the complementary data sets have been used to constrain the non-unitarity parameters. We have also found that the T2K and NOvA t…
Towards a New Minimal SO(10) Unification
2012
We argue that non-supersymmetric SO(10) models based on a renormalizable Higgs sector in which spontaneous symmetry breaking is triggered by the VEVs of a 45-dimensional adjoint and a 126-dimensional tensor representations can provide a potentially realistic yet relatively simple framework for a future robust estimate of the proton lifetime. Following closely the work Phys.Rev.D85, 095014 (2012), arXiv: 1202.0807 [hep-ph] we comment on the gauge unification constraints on the B-L breaking scale and show that there are several regions in the parameter space of the minimal model where the seesaw scale in the phenomenologically favoured ballpark of around 10^13-14 GeV is consistently supported.
Probing CP violation with non-unitary mixing in long-baseline neutrino oscillation experiments: DUNE as a case study
2016
When neutrino masses arise from the exchange of neutral heavy leptons, as in most seesaw schemes, the effective lepton mixing matrix $N$ describing neutrino propagation is non-unitary, hence neutrinos are not exactly orthonormal. New CP violation phases appear in $N$ that could be confused with the standard phase $\delta_{\text{CP}}$ characterizing the three neutrino paradigm. We study the potential of the long-baseline neutrino experiment DUNE in probing CP violation induced by the standard CP phase in the presence of non-unitarity. In order to accomplish this we develop our previous formalism, so as to take into account the neutrino interactions with the medium, important in long baseline…
Leptogenesis with small violation of B-L
2012
We analyze leptogenesis in the context of seesaw models with almost conserved lepton number, focusing on the L-conserving contribution to the flavoured CP asymmetries. We find that, contrary to previous claims, successful leptogenesis is feasible for masses of the lightest heavy neutrino as low as M1 ~ 10^6 GeV, without resorting to the resonant enhancement of the CP asymmetry for strongly degenerate heavy neutrinos. This lower limit renders thermal leptogenesis compatible with the gravitino bound in supersymmetric scenarios.
Future CEvNS experiments as probes of lepton unitarity and light-sterile neutrinos
2020
We determine the sensitivities of short-baseline coherent elastic neutrino-nucleus scattering (CE$\nu$NS) experiments using a pion decay at rest neutrino source as a probe for nonunitarity in the lepton sector, as expected in low-scale type-I seesaw schemes. We also identify the best configuration for probing light sterile neutrinos at future ton-scale liquid argon CE$\nu$NS experiments, estimating the projected sensitivities on the sterile neutrino parameters. Possible experimental setups at the Spallation Neutron Source, Lujan facility and the European Spallation Source are discussed. Provided that systematic uncertainties remain under control, we find that CE$\nu$NS experiments will be c…
Light majoron cold dark matter from topological defects and the formation of boson stars
2019
We show that for a relatively light majoron ($\ll 100 $ eV) non-thermal production from topological defects is an efficient production mechanism. Taking the type I seesaw as benchmark scheme, we estimate the primordial majoron abundance and determine the required parameter choices where it can account for the observed cosmological dark matter. The latter is consistent with the scale of unification. Possible direct detection of light majorons with future experiments such as PTOLEMY and the formation of boson stars from the majoron dark matter are also discussed.
Minimal Supergravity Scalar Neutrino Dark Matter and Inverse Seesaw Neutrino Masses
2008
We show that within the inverse seesaw mechanism for generating neutrino masses minimal supergravity is more likely to have a sneutrino as the lightest superparticle than the conventional neutralino. We also demonstrate that such schemes naturally reconcile the small neutrino masses with the correct relic sneutrino dark matter abundance and accessible direct detection rates in nuclear recoil experiments.
Emotional Seesaw, Compliance, and Mindlessness
2001
Research on emotion conducted so far has ignored situations where the subject experiences a certain emotion, but where the external stimulus that evoked and upholds this emotion suddenly disappears. This kind of situation, however, is relatively common in everyday life. This article attempts to recognize certain consequences of those conditions under which the stimuli justifying our experience of such emotional states as fear or joy suddenly disappear. Research done to date by the author and colleagues indicates increased compliance of the subject when addressed with various requests, commands, or suggestions in the situation termed here “emotional seesaw.” The classical “live” example tha…