Related papers: Heavy neutrinos production and decay in future $e^…
The production of the three normal neutrinos via $e^-e+$ collision at $Z$-boson peak (neutrino production in a Z-factory) is investigated thoroughly. The differences of $\nu_e$-pair production from $\nu_\mu$-pair and $\nu_\tau$-pair…
The complete matrix element for $e^+e^-\ar b\bar bZ^0Z^0$ has been computed at tree--level and applied to $Z^0H^0$--production followed by $Z^0\ar b\bar b$ and $H^0\ar Z^0Z^0$, including all the irreducible background, at Next Linear…
Production of heavy Majorana neutrino $N_{e}$ predicted by left-right symmetric extension of the Standard Model at future {\normalsize TeV} scale $ep$ colliders have been considered. In order to estimate potential of $ep$ colliders for…
Whether in nature exists Majorana neutrino is one of the most fundamental questions in physics. It is directly related to the violation of accidental $U(1)$-lepton number symmetry(LNV). Enormous efforts had been put into such test and among…
We consider the electromagnetic production of positron in collision of slow heavy nuclei, with the simultaneously produced electron captured by one of the nuclei. The cross-section of the discussed process exceeds essentially the…
The problem of CP conservation and CP violation for two heavy neutrinos production in $e^+e^-$ interaction is considered. Very convenient way of parametrization of the neutrino mass matrix, from which necessary and sufficient condition for…
We discuss the production of heavy leptons at a future high--energy $e^+e^-$ linear collider with a center of mass energy of 500 GeV. Signals and backgrounds are analyzed for their single production in association with ordinary leptons.…
We update present bounds on the helicity of the neutrinos produced in muon decay, including e+ e- -> fbar f LEP 2 data. These significantly reduce the limits derived from all the other electroweak precision data. In Standard Model…
We investigate the potential of the 100 TeV future circular collider (FCC-hh) to probe heavy neutrinos. We concentrate in particular on heavy neutrino production via a $U(1)_{B-L}$ $Z'$ gauge boson and contrast the resulting limits with…
In gauge models with bigger number of Higgs particles their couplings to fermions are more complicated then in the standard model (SM). The influence of the Higgs bosons exchange on the neutrino production cross section in $e^-e^+$…
We propose a new strategy to probe heavy neutrinos with non-universal fermion couplings at the Large Hadron Collider (LHC) using a novel production mechanism and machine-learning algorithms. Focusing on proton--proton collisions at…
We revisit the constraints on the properties of right handed neutrinos from the requirement to explain the observed light neutrino oscillation data in the type-I seesaw model. We use well-known relations to show that there is in general no…
We discuss the impact of heavy neutrino-antineutrino oscillations (NNOs) on heavy neutral lepton (HNL) searches at proposed electron-positron colliders such as the future circular $e^+e^-$ collider (FCC-ee). During the $Z$ pole run, HNLs…
We investigate possibilities for detecting heavy Majorana neutrinos ($N$'s) in $e^+e^-$ at LEP200 and future Linear Colliders. We concentrate on the processes where the pairs of intermediate heavy $N$'s produce a clear signal of total…
The lepton number violating process, $e^- e^- \to W^- W^-$ has been widely discussed in the Majorana neutrino exchange mechanism. Here, we discuss this process in a composite neutrino model where excited Majorana neutrinos are exchanged. We…
We discuss the prospects of detecting the processes $e^+p\to\bar\nu_e\ell^+\ell'^+X$ and $\nu_ep\to e\ell^+\ell'^+X$ ($\ell,\ell'=e,\mu,\tau$) under the conditions of the present $ep$ collider HERA and of future colliders. These high-energy…
Extensions of the Standard Model are required to give mass to the light neutrinos and explain neutrino oscillations. One of the simplest ideas is to introduce new heavy, gauge singlet fermions that play the role of right-handed neutrinos in…
We discuss W and Z production through the deep inelastic neutrino-nucleon scattering in the context of the standard model SU(3)x SU(2)x U(1) of the strong and electroweak interactions. We find the cross section rates for the process…
The complete matrix element for $e^+e^-\ar W^+W^-\bar b b$ is computed at tree level and applied to: {\bf a)} $\bar t t$ production and decay ; {\bf b)} $ZH$ production followed by $Z\ar \bar bb$ and $H\ar WW$. In both cases we include…
A high energy linear e^+e^- collider (LC) can also be used as a Photon Collider (PC), using Compton scattering of laser photons on the e^+/e^- beams. The leading order cross-section for the production of heavy quarks, e^+e^- -> e^+e^-…