Related papers: Generation-changing interaction of sneutrinos in $…
We consider the production and decay of selectrons and charginos in $e^-e^-$ collisions. The advantage over usual $e^+e^-$ collisions is the very low level of standard model backgrounds which should make the discovery of selectrons or…
The cross section for the reaction $e^{-}e^{-} \to \ell^-\ell^-$ ($\ell=\mu,\tau$) is calculated in models with heavy Majorana neutrinos mediating lepton number violating amplitudes at the loop level. The contributing four-point functions…
We study the single production of sneutrinos with two leptons (or jets) via $\gamma\gamma$ collision in an R-parity ($R_{p}$) violating supersymmetric model. The subsequent decays of the sneutrino are also considered. The single production…
If a fourth generation of leptons exists, both the neutrino and its charged partner must be heavier than 45 GeV. We suppose that the neutrino is the heavier of the two, and that a global or discrete symmetry prohibits intergenerational…
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…
We study the single production of heavy neutrinos via the processes $e^-e^+ \to \nu N$ and $e^-\gamma \to W^- N$ at future linear colliders. As a base of our considerations we take a wide class of models, both with vanishing and…
We study the production and leptonic decay of charginos in collisions of polarized photon beams including the complete spin correlations. The photons can be generated by Compton backscattering of polarized laser pulses off a polarized…
The radiative decay of ultrarelativistic massive neutrino $\nu_i \rightarrow \nu_j \gamma$ is investigated in electromagnetic fields in the framework of the Standard Model with lepton mixing. Estimates of the decay probability and ``decay…
A search, in e^+e^- collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants lambda_ijk or…
Models of neutrino masses are discussed capable of explaining in a natural way the maximal mixing between $\nu_{\mu}$ and $\nu_{\tau}$ observed by the Super-Kamiokande collaboration. For three generations of leptons two classes of such…
In the framework of the Standard Model with lepton mixing the radiative decay $\nu_i \rightarrow \nu_j \gamma$ of a neutrino of high ($E_\nu \sim 100 \, GeV$) and super-high ($E_\nu \ge 1 \, TeV$) energy is investigated in the Coulomb field…
Lepton mixing can originate from the breaking of a flavor symmetry in different ways in the neutrino and the charged lepton sector. We propose an extension of this framework which allows to connect the mixing parameters with masses, and…
If any heavy neutral leptons are discovered in accelerator-based experiments, key questions will involve their possible connection to neutrino masses or leptogenesis. Working in a renormalisable extension of the Standard Model by three…
The cross sections and forward-backward asymmetries of hadronic and leptonic events produced in e+e- collisions at centre-of-mass energies of 130-183 GeV are presented. Results for ee, mumu, tautau, qq, bb and cc production show no…
We discuss the pair production of charginos in collisions of polarized photons $\gamma\gamma \to \tilde{\chi}_i^+ \tilde{\chi}_i^-$, ($i=1,2$) and the subsequent leptonic decay of the lighter chargino $\tilde{\chi}_1^+ \to \tilde{\chi}_1^0…
Explicit formulas which describe muon pair production in reaction $\gamma\nu \to \mu^+ \mu^- \nu$ through neutrino magnetic moment are obtained and used to derive in the leading approximation cross section of muon pair production in $\nu…
We perform a systematic study of sneutrino production and decays in the Minimal Supersymmetric Standard Model (MSSM) with lepton flavour violation (LFV). We study bosonic decays of sneutrinos as well as fermionic ones. We show that the…
Possible generation structure is investigated. We considere alternative possibility of combination of leptons and quarks to compose each generation, where the combination of $(\nu_{\tau},{\tau})$ and $(u,d)$ compose a generation. Our model…
In the type-I seesaw model the size of mixing between light and heavy neutrinos, nu and N, respectively, is of order the square root of their mass ratio, (m_nu/m_N)^(1/2), with only one generation of the neutrinos. Since the light-neutrino…
A search for chargino, neutralino and scalar lepton pair-production in e+e- collisions at the centre-of-mass energy of 189 GeV is performed under the assumptions that R-parity is not conserved in decays and only one of the coupling…