Lepton mixing and neutrino masses from A5 and CP

Some properties of lepton mixing and neutrino masses can be computed under the assumption of A5 and CP as a symmetry in the leptonic sector. The results show that four mixing patterns accommodate well the oscillation data, i.e. all the mixing angles are in the 3sigma confidence region. We also introduce an explicit realization of this framework in the case of the Weinberg operator where the neutrino mass spectrum can be computed.Comment: Poster presented at NuPhys2015 (London, 16-18 December 2015). 5 pages, LaTeX, 2 pdf figure

Probability Densities of the effective neutrino masses mβm_{\beta } and mββm_{\beta \beta}

We compute the probability densities of the effective neutrino masses $m_{\beta }$ and $m_{\beta \beta}$ using the Kernel Density Estimate (KDE) approach applied to a distribution of points in the $(m_{\min}, m_{\beta\beta })$ and $(m_{\beta }, m_{\beta\beta })$ planes, obtained using the available Probability Distribution Functions (PDFs) of the neutrino mixing and mass differences, with the additional constraints coming from cosmological data on the sum of the neutrino masses. We show that the reconstructed probability densities strongly depend on the assumed set of cosmological data: for $\sum_j m_j \leq 0.68\ @\ 95\% \ \mathrm{CL}$ a sensitive portion of the allowed values are already excluded by null results of experiments searching for $m_{\beta \beta}$ and $m_{\beta }$, whereas in the case $\sum_j m_j \leq 0.23\ @\ 95\% \ \mathrm{CL}$ the bulk of the probability densities are below the current bounds.Comment: 12 pages, 6 figures, 4 tables. Improved discussion and references added, typos corrected, matches published version in NP

Phenomenology of SU(5) low-energy realizations: the diphoton excess and Higgs flavor violation

We discuss different $\rm SU(5)$ low-energy realizations and illustrate their use with the diphoton excess and Higgs flavor violation, which require new physics at the TeV scale. In particular, we study two scenarios for a $750$ GeV resonance: in the first one the resonance belongs to the adjoint of $\rm SU(5)$, being either an $\rm SU(2)_L$ singlet or a triplet, while in the second case the signal is due to the CP-even and CP-odd states of a new $\rm SU(2)_L$ Higgs doublet belonging to a ${\bf 45}_H$ or a ${\bf 70}_H$ representations, giving rise to a two-Higgs doublet model at low energies. We study the fine-tuning needed for the desired members of the multiplets to be light enough, while having the rest at the GUT scale. In these scenarios, the production and decay into photons of the new resonance are mediated by the leptoquarks (LQ) present in these large $\rm SU(5)$ representations. We analyse the phenomenology of such scenarios, focusing on the most relevant predictions that can help to disentangle the different models, like decays into gauge bosons, Standard Model (SM) fermions and LQs pair production. In the case of the ${\bf 45}_H$ (the Georgi-Jarlskog model), we also study the possibility to have Higgs flavor violation. We find that $B_s$ mixing limits (in addition to $\tau\rightarrow \mu \gamma$) always imply that $\rm{BR}(h\rightarrow \tau\mu,\,bs)\lesssim 10^{-5}$.Comment: Minor clarifications and references added, typos corrected, matches published version in NP

Neutrino masses and lepton mixing from A5×CPA_5\times{\rm CP}

We analyse in detail the phenomenological implications for lepton masses and mixing derived by the breaking of the discrete symmetries $A_5 \times CP$ into the subgroups $Z_2 \times CP$ in the neutrino sector and $Z_5$ in the charged lepton sector. We derive accurate analytic expressions for the sum of the neutrino masses $\Sigma_i m_i$ as well as for the effective Majorana masses $m_\beta$ and $m_{\beta \beta}$ under different hypotheses for the flavon vevs and compare them with the exact numerical results obtained from the diagonalization of the neutrino mass matrix.Comment: 40 pages, 9 figure

Lepton mixing from the interplay of the alternating group A5 and CP

Abstract: Assuming three generations of Majorana neutrinos, we study the different mixing patterns that arise from the non-trivial breaking of the flavor group A5 and CP to the residual symmetries Z3, Z5 or Z2 × Z2 in the charged lepton and to Z2 × CP in the neutrino sector. All patterns contain only one free parameter θ and thus mixing angles as well as the Dirac and the two Majorana phases are strongly correlated. We perform an analytical and a numerical study of all possible mixing patterns. It turns out that only four patterns can describe the experimentally measured values of the mixing angles for a particular choice of θ well. All of them predict trivial Majorana phases, while the Dirac phase δ is maximal for two patterns and trivial for the two remaining ones. If δ is maximal, also the atmospheric mixing angle is fixed to be maximal