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 $z\sim 15-20$ 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 $\nu_i \to \nu_j\,\gamma$ induced by effective magnetic and electric transition moments ($\mu_\text{eff}$) are precluded by the tight astrophysical constraints on $\mu_\text{eff}$. 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 b→sb\to s anomalies with a dark sector

The LHCb collaboration has recently reported on some anomalies in $b\to s$ 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 $U(1)$ gauge symmetry. The spontaneous breaking of this symmetry gives rise to a massive $Z^\prime$ boson, which communicates the SM particles with a valid dark matter candidate, while solving the $b\to s$ anomalies with contributions to the relevant observables.Comment: 9 pages, 4 figures. Few typos corrected, references adde