Related papers: Signals of Unconventional E$_6$ Models at $e^+e^-$…
Neutrinos in the Standard Model (SM) are considered to be massless which is in contradiction with the evidence from the neutrino oscillation data. These experiments established that at least two SM neutrinos have non-zero masses and that…
Very little is known about the mass spectrum of fermions in the standard model. In this talk, I point out that in the simplest extension of the standard model, in which all right-handed fields are singlets, it is quite possible that a…
A recent study [1] has shown that a simplified model predicting a heavy scalar of mass 270 GeV ($H$) that decays to a Standard Model (SM) Higgs boson in association with a scalar singlet of mass 150 GeV ($S$) can accommodate several…
A broad class of supersymmetric extensions of the standard model predict a Z' vector boson whose mass is naturally in the range 250 GeV < M_Z' < 2 TeV. To avoid unacceptably large mixing with the Z, one requires either a discrete tuning of…
Though the minimal model of anomaly mediated supersymmetry breaking has been significantly constrained by recent experimental and theoretical work, there are still allowed regions of the parameter space for moderate to large values of…
Cross-section and angular distributions for hadronic and lepton-pair final states in e+e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, are presented and compared with the…
We study how the exotic particles and supersymmetric partners would affect the discovery limit at the Tevatron and LHC for neutral gauge bosons in generic E_6 models. We examine the Z' decay in the extreme case that all of the particles are…
The breakdown of E_6 gauge symmetry at high energies may lead to supersymmetric (SUSY) models based on the Standard Model (SM) gauge group together with extra U(1)_{\psi} and U(1)_{\chi} gauge symmetries. To ensure anomaly cancellation the…
We study a model in which lepton number violation is solely triggered by a dimension 4 hard breaking term in the scalar potential. A minimal model which contains a SU(2) triplet with hypercharge Y=2, and a pair of singlet doubly charged…
We discuss some phenomenological aspects of an $E_6$ inspired supersymmetric standard model with an extra $U(1)_{N}$ gauge symmetry under which right-handed neutrinos have zero charge, allowing a conventional see-saw mechanism. The $\mu$…
A heavy triplet of leptons $(\Sigma^+, \Sigma^0, \Sigma^-)_R$ per family is proposed as the possible anchor of a small seesaw neutrino mass. A new U(1) gauge symmetry is then also possible, and the associated gauge boson $X$ may be…
We propose a non-supersymmetric SU(5) model in which only the third family of fermions are unified. The model remedies the non-unification of the three Standard Model couplings in non-supersymmetric SU(5). It also provides a mechanism for…
We discuss the production of the doubly charged leptons in future linear electron positron colliders, such as the International Linear Collider and Compact Linear Collider. Such states are introduced in extended weak-isospin multiplets by…
A search for physics beyond the standard model in events with at least three charged leptons (electrons or muons) is presented. The data sample corresponds to an integrated luminosity of 137 fb$^{-1}$ of proton-proton collisions at…
The existence of extra chiral generations with all fermions heavier than $M_Z$ is strongly disfavored by the precision electroweak data. The exclusion of one additional generation of heavy fermions in SUSY extension of Standard Model is…
We consider the production at the LHC of exotic composite leptons of charge Q=+2e. Such states are allowed in composite models which contain extended isospin multiplets (Iw=1 and Iw=3/2). These doubly charged leptons couple with Standard…
We search for signatures of the extra neutral gauge boson $ Z^\prime$, predicted in some extensions of the Standard Model, from the analysis of some distributions for $p + p \longrightarrow \mu^+ + \mu^- + X$, where the only exotic particle…
We study the non-standard interactions of neutrinos with light leptonic scalars ($\phi$) in a global $(B-L)$-conserved ultraviolet (UV)-complete model. The model utilizes Type-II seesaw motivated neutrino interactions with an…
It was recently suggested that the reported anomalies in $R_b$ and $R_c$ can be interpreted as the effect of a heavy vector boson that couples to quarks and is universally decoupled from leptons. We examine how an extra gauge boson with…
In light of the ongoing effort on reducing the theoretical uncertainties and an upcoming experiment concerning muon magnetic moment, we perform a detailed study of an 3-4-1 electroweak gauge extension of the standard model that contains…