Related papers: $S_4$ symmetric four-generation models for charged…
Leptogenic supersymmetry is a scenario characterized by cascade decays with copious lepton production. Leptogenic models have striking signatures that can be probed by the LHC even in the 10 TeV run with as little as 200 pb^-1 of data,…
We propose to identify the excess of events with four charged leptons at $E\sim 325\GeV$ seen by the CDF and CMS Collaborations with a new `sterile' scalar particle characterized by a very narrow resonance of the same height and branching…
A search for supersymmetry in events with four or more charged leptons (electrons, muons and $\tau$-leptons) is presented. The analysis uses a data sample corresponding to $139\,\mbox{fb\(^{-1}\)}$ of proton-proton collisions delivered by…
We study the phenomenological implications of the modular symmetry $\Gamma(3) \simeq A_4$ of lepton flavors facing recent experimental data of neutrino oscillations. The mass matrices of neutrinos and charged leptons are essentially given…
We review the possible role that multi-Higgs models may play in our understanding of the dynamics of a heavy 4th sequential generation of fermions. We describe the underlying ingredients of such models, focusing on two Higgs doublets, and…
The minimal model of spontaneously broken leptonic colour and discrete quark-lepton symmetry predicts that charged leptons have the same masses as their partner charge $+2/3$ quarks up to small radiative corrections. By invoking a different…
An approximate Z_3 family symmetry is proposed for leptons which results in a neutrino mass matrix with sin^2 2 theta_atm = 1 and tan^2 theta_sol = 0.5, but the latter value could easily be smaller. A generic requirement of this approach is…
We explore an extension of the fourth generation model with multi-Higgs doublets and three fermion singlets. The Standard Model neutrinos acquire mass radiatively at one loop level while the fourth generation neutrinos acquire a heavy…
We study leptogenesis in the supersymmetric standard model plus the seesaw. We identify important qualitative differences that characterize supersymmetric leptogenesis with respect to the non-supersymmetric case. The lepton number…
We propose a unique lepton mixing scheme and its association with an exact hierarchy-philic neutrino mass matrix texture in the light of Type-I+Type-II seesaw mechanism under the framework of $A_4 \times Z_{10}$ discrete flavour symmetry.…
We study the pair production of $\tilde{l}_{4}$, which is the supersymmetric partner of the fourth family charged lepton, at the $e^{+}e^{-}$ colliders. It is shown that the investigation of this process at ILC/CLIC will give opportunity to…
We propose a minimal inverse seesaw model with $S_4$ symmetry for the Majorana neutrinos with only one real ($m_0$)-and two complex ($\alpha, \beta$) parameters in neutrino sector which gives reasonable predictions for the neutrino…
We consider the contributions to $g_\mu-2$ from fourth generation heavy neutral and charged leptons, $N$ and $E$, at the one-loop level. Diagrammatically, there are two types of contributions: boson-boson-$N$, and $E$-$E$-boson in the loop…
The Standard Model has three generations of fermions and although it does not contain any explicit reason for this, the existence of additional generations is now very constrained by experiment. Present measurements are saturating…
We present a very simple 4th-generation (4G) model with an Abelian gauge interaction under which only the 4G fermions have nonzero charge. The U(1) gauge symmetry can have a Z_2 residual discrete symmetry (4G-parity), which can stabilize…
Viable neutrino and charged lepton masses and mixings are obtained by imposing a $S_3 \times Z_4 \times Z_3$ flavor symmetry in a model with a few additional Higgs. We use two $SU(2)_L$ triplet Higgs which are arranged as a doublet of…
We study an extension of the standard model based on the flavor symmetry A4 only. Neutrino Majorana mass terms arise from dimension five operator and charged lepton masses from renormalizable Yukawa couplings. We introduce three Higgs…
The simplest neutrino mass models based on $A_4$ symmetry predict $\theta_{13} = 0$ at tree level, a value that contradicts recent data. We study models that arise from the spontaneous breaking of an $SO(3)$ symmetry to its $A_4$ subgroup,…
We investigate the supersymmetric A_4 model recently proposed by Babu, Ma and Valle. The model naturally gives quasi-degenerate neutrinos that are bi-largely mixed, in agreement with observations. Furthermore, the mixings in the quark…
We consider a model for quark and lepton masses and mixings based on S4 flavor symmetry. The model contains six Higgs doublets where three of them give mass to the leptons and the other three gives mass to the quarks. Charged fermion and…