Related papers: Experimental and Theoretical Implications of New S…
A signal of two leptons and missing energy is challenging to analyze at the Large Hadron Collider (LHC) since it offers only few kinematical handles. This signature generally arises from pair production of heavy charged particles which each…
We propose a predictive lepton model under a modular $S_4$ symmetry, where the neutrino mass matrix arises from a radiative seesaw at one-loop level. The tree-level mass matrix is forbidden by well-assigned modular weights, which also play…
We calculate flavour dependent lepton asymmetries within the $E_6$ inspired Supersymmetric Standard Model ($\rm E_6SSM$), which has an extra $U(1)_N$ symmetry. In this model, the right-handed neutrino doesn't participate in gauge…
The seesaw model of heavy and light Majorana neutrinos and its low-energy effective theory are studied, when the number of heavy neutrinos is equal to or less than the number of light lepton generations. We establish a general relationship…
In this paper, an electroweak model with massive neutrinos is proposed. The symmetry of the model is $SU(2)_L \times U(1)_Y \times U(1)_M$. Because of the mixing of neutrinos, the conversion of one lepton type to another is possible, but…
Following a prediction made in Refs.~\cite{vonBuddenbrock:2015ema,Kumar:2016vut,vonBuddenbrock:2016rmr}, this paper focuses on multi-lepton signatures arising from two new hypothetical scalar bosons, $H$ and $S$, at the Large Hadron…
We investigate the single and pair production of new heavy leptons via string inspired $E_{6}$ model at future linear colliders. Signal and corresponding backgrounds for these leptons are studied. We have found that single production of…
We study bounds on a neutral component of weak doublet scalar lepton. A typical example of such particle is sneutrinos in supersymmetric models. Using constraints from invisible Higgs decays we place a lower bound of approximately $m_h/2$.…
New heavy charged lepton production and decay signatures at future electron-positron colliders are investigated at $\sqrt {s}=500$ GeV. The consequences of model dependence for vector singlets and vector doublets are studied. Distributions…
Heavy neutral leptons $N$ are the most appealing candidates to generate the tiny neutrino masses. In this paper, we study the signature of heavy neutral leptons in gauged $U(1)_{L_\mu-L_\tau}$ at a muon collider. Charged under the…
Extending the standard model with three right-handed neutrinos ($N_k$) and a second Higgs doublet ($\eta$), odd under the discrete parity symmetry $Z_2$, Majorana neutrino masses can be generated at 1-loop order. In the resulting model, the…
We discuss the most general necessary and sufficient condition for three massless light neutrinos in variants of the type I seesaw mechanism in which we introduce an arbitrary number of fermionic gauge singlets. We find that having massless…
We study the effects induced by new neutral fermions below their mass threshold, due to their possible mixing with the standard neutrinos. We use as experimental constraints the recent results on lepton universality, together with the…
We discuss the relation between leptogenesis and the MNS phases in the class of see-saw models called light sequential dominance in which the right-handed neutrinos dominate sequentially, with the dominant right-handed neutrino being the…
Heavy neutrinos with masses below the electroweak scale can simultaneously generate the light neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis. The requirement to explain these phenomena…
We propose a new nonthermal leptogenesis mechanism triggered by the cosmic first-order phase transition. The Standard Model is extended with two generations of TeV-scale vectorlike leptons. The lighter generation gives rise to an inverse…
We reexamine lepton mixing in gauge models by considering two theories within the type I seesaw mechanism, the Extended Standard Model, i.e. SU(2)_L \times U(1)_Y with singlet right-handed heavy neutrinos, and the Left-Right Model SU(2)_L x…
A recent model of dark energy and dark matter was proposed, involving a new gauge group $SU(2)_Z$ whose coupling grows strong at a scale $\Lambda_Z \sim 10^{-3} eV$, a result which is obtained from a simple assumption that its initial value…
We analyze a multi-lepton signal plus missing transverse energy from neutrinos expected at the LHC for a Bino-like neutralino as the lightest supersymmetric particle (LSP), when the left sneutrino is the next-to-LSP and hence a suitable…
The top quark is the heaviest known elementary particle of the Standard Model (SM) of particle physics and, therefore, it is expected to have large couplings to hypothetical new physics in many models beyond the SM (BSM). Various studies…