546 research outputs found
Radiative origin of neutrino masses
Mechanisms for Majorana neutrino mass generation can be classified according
to the level at which the Weinberg operator is generated. The different
possibilities can be sorted in "canonical" tree level and loop-induced
realizations, the latter being motivated by their potential experimental
testability. Here we discuss the one- and two-loop cases, paying special
attention to systematic classification schemes which aim at building a full
picture of neutrino mass generation.Comment: 7 pages, 3 figures. Contribution to the proceedings of the XXXIX
International Conference of Theoretical Physics "Matter to the Deepest",
Ustron, Poland, September 13-18, 201
Implications of finite one-loop corrections for seesaw neutrino masses
In the standard seesaw model, finite corrections to the neutrino mass matrix
arise from one-loop self-energy diagrams mediated by a heavy neutrino. We
discuss the impact that these corrections may have on the different low-energy
neutrino observables paying special attention to their dependence with the
seesaw model parameters. It is shown that sizable deviations from the
tri-bimaximal mixing pattern can be obtained when these corrections are taken
into account.Comment: 4 pages, 3 figures. Prepared for the proceedings of the 12th
International Conference on Topics in Astroparticle and Underground Physics
(TAUP 2011), Munich, Germany, 5-9 September 201
Scalar triplet leptogenesis without right-handed neutrino decoupling
We discuss leptogenesis in the context of type-II seesaw in the case in which
in addition to the scalar electroweak triplet decays the lepton asymmetry is
also induced by right-handed neutrino decays (mild hierarchical scenarios). We
show that within this setup, depending on the relative sizes of the relevant
parameters, one can identify three classes of generic models, each one with its
own consequences for leptogenesis.Comment: 3 pages, 2 figures. Prepared for the proceedings of the Neutrino
Oscillation Workshop 2012 (NOW 2012), Conca Specchiulla (Otranto, Lecce,
Italy), September 9-16, 201
One-loop finite corrections to seesaw neutrino masses
In the standard seesaw model, finite corrections to the neutrino mass matrix
arise from one-loop self-energy diagrams mediated by heavy neutrinos. We
discuss the impact that these corrections may have on the different entries of
the tree-level effective neutrino mass matrix, paying special attention to
their dependence with the seesaw model parameters. We also briefly comment on
the implications these corrections might have on low-energy neutrino
observables.Comment: 3 pages, 2 figures. Prepared for the proceedings of the International
Europhysics Conference on High Energy Physics, EPS-HEP 2011, Grenoble,
France, July 21-27 201
The EDGES signal: An imprint from the mirror world?
Recent results from the Experiment to Detect the Global Epoch of Reionization
Signature (EDGES) show an anomalous spectral feature at redshifts
in its 21-cm absorption signal. This deviation from cosmological predictions
can be understood as a consequence of physics that either lower the hydrogen
spin temperature or increases the radiation temperature through the injection
of soft photons in the bath. In the latter case, standard model neutrino decays
induced by effective magnetic and electric transition
moments () are precluded by the tight astrophysical constraints
on . We show that if mirror neutrinos are present in the bath
at early times, an analogous mechanism in the mirror sector can lead to a
population of mirror photons that are then "processed" into visible photons
through resonant conversion, thus accounting for the EDGES signal. We point out
that the mechanism can work for mirror neutrinos which are either heavier than
or degenerate with the standard model (SM) neutrinos, a scenario naturally
realized in mirror twin Higgs models.Comment: 8 pages, 2 figure
Shedding light on the anomalies with a dark sector
The LHCb collaboration has recently reported on some anomalies in
transitions. In addition to discrepancies with the Standard Model (SM)
predictions in some angular observables and branching ratios, an intriguing
hint for lepton universality violation was found. Here we propose a simple
model that extends the SM with a dark sector charged under an additional
gauge symmetry. The spontaneous breaking of this symmetry gives rise to a
massive boson, which communicates the SM particles with a valid dark
matter candidate, while solving the anomalies with contributions to
the relevant observables.Comment: 9 pages, 4 figures. Few typos corrected, references adde
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