Related papers: Heavy neutrinos production and decay in future $e^…
Top quark studies at future $e^+e^-$ colliders are considered. Two issues are discussed: {a --}Some results are presented on the decays of top quarks. Energy distributions of charged leptons and neutrinos in $t\to bW\to be^+\nu$ and jets in…
We discuss the process $e^-e^- \to W^- W^-$ mediated by heavy Majorana neutrino exchange in the t- and u channel. In our model the cross section for this reaction is a function of the masses (m_N) of the heavy Majorana neutrinos and mixing…
We discuss the current status and future prospects of heavy neutrino searches at the energy frontier, which might play an important role in vindicating the simplest seesaw paradigm as the new physics responsible for neutrino mass…
Theoretical and experimental situation in physics of heavy neutrinos $(M_N>M_Z)$ is briefly presented. Various experimental bounds on heavy neutrino masses and mixings are shortly reviewed. Special attention is paid to possibility of…
The heavier chargino decay could yield two charged leptons of different generations, owing to generation mixing of sneutrinos. We discuss the possibility of producing $e$ and $\mu$ through this process in near future collider experiments.…
We study the production and decay of heavy selectrons in the electron-photon mode of a linear collider of the next generation. The standard model backgrounds can be substantially reduced by appropriate kinematical cuts. As a consequence,…
Light gravitino productions in association with a neutralino (selectron) in e^+e^- (e^-\gamma) collisions are restudied in a scenario that the lightest supersymmetric particle is a gravitino and the produced neutralino (selectron) promptly…
We revisit the process of inverse neutrino-less double beta decay (e e -> W W) at future linear colliders. The cases of Majorana neutrino and Higgs triplet exchange are considered. We also discuss the processes e mu -> W W and mu mu -> W W,…
A charged Higgs pair can be produced at an ee collider through a t-channel exchange of a heavy neutrino (N) via e^+ e^- -> H^+ H^- and, if N is a Majorana particle, also via the lepton number violating (LNV) like-sign reaction e^\pm e^\pm…
In this study, Higgs production processes, Higgsstrahlung and vector boson (W and Z) fusion processes, were investigated for four different future lepton colliders (CEPC, ILC, CLIC, and FCC-ee). The cross sections for each production…
We study signatures of heavy Majorana neutrinos at e- gamma colliders. Since these particles violate lepton number, they can give rise to the reactions e- gamma -> W- W- e+ and e- gamma -> W+ mu- mu- nu. The Standard Model background…
We discuss the production, at high--energy e$^+$e$^-$ linear colliders, of new heavy fermions predicted by extensions of the Standard Model. We analyze in great details the various signals and the corresponding backgrounds for both pair…
A new method is proposed to reconstruct the neutrinos in the $e^+e^-\to Zh$ process followed by the $h\to\tau\tau$ decay. With the help of a refined Higgs momentum reconstruction from the recoiling system and the impact parameters, high…
We investigate the pair-production of right-handed neutrinos via the Standard Model (SM) Higgs boson in a gauged $B-L$ model. The right-handed neutrinos with a mass of few tens of GeV generating viable light neutrino masses via the seesaw…
Many extensions of the Standard Model include extra fermions. We here consider a model containing Dirac neutral heavy leptons in addition to massless neutrinos. These neutral heavy leptons can be produced singly along with a massless…
We study a new production mechanism for heavy neutrinos at the LHC, which dominates over the usually considered $s$-channel $W$-exchange diagram for heavy-neutrino masses larger than 100 - 200 GeV. The new mechanism is infrared-enhanced by…
We study the process $e^+e^- \to W^+W^-$ with the aim of estimating the prospects for observing heavy neutrinos contributions at future $e^+e^-$-colliders. In this work, we consider two implementations of heavy-light neutrino mixing: a…
Measurability of generation mixing is studied on the pair production of sneutrinos in $e^+e^-$ collisions and their subsequent decays into two different charged leptons $e$ and $\mu$ with two lighter charginos. The analyses are made…
We explore the discovery prospect of a very heavy neutrino at the proposed $e^+e^-$ collider for two different c.m.energies $\sqrt{s}=1.4$ TeV and 3 TeV. We consider production of heavy neutrino via $s$ and $t$-channel processes, and its…
The complete matrix element for $e^+e^-\ar b\bar bW^+W^-$ has been computed at tree--level and applied to $Z^0H^0$ production followed by $Z^0\ar b\bar b$ and $H^0\ar W^+W^-$, keeping into account all irreducible backgrounds, which are…