Production of heavy Majorana neutrino $N_{e}$ predicted by left-right symmetric extension of the Standard Model at future { ormalsize TeV} scale $ep$ colliders have been considered. In order to estimate potential of $ep$ colliders for $N_{e}$ search
we consider back-groundless process $e^{-}prightarrow e^{+}X$ which is consequence of Majorana nature of $N_{e}$. It is shown that { ormalsize linac-LHC} and { ormalsize linac-FCC} based $ep$ colliders will cover much wider regions of $N_{e}$ and $W_{R}$ masses than corresponding linear electron-positron colliders.
IceCube collaboration has published two papers on ultrahigh energy neutrinos observation, recently. They have used the data collected in two years in their first publication, which reveals observation of two PeV energy neutrino events. The second pub
lication of the collaboration including more data has also confirmed main features of the former paper. In literature, various interpretations of the IceCube data have been proposed. In this study, it is shown that PeV energy neutrino events observed by the IceCube collaboration can be interpreted as resonance production of color octet neutrinos with masses in $500-800$ GeV range.
In this work, we investigated resonant production of spin-3/2 color octet electron at the Large Hadron electron Collider (LHeC). Signal and background analysis have been performed and discovery, observation and exclusion limits are determined for spi
n 3/2 color octet electron masses. Reachable values of the compositeness scale are presented as a function of the spin-3/2 color octet electron masses.
In this work we consider pair production of LSP tau-sneutrinos at the Compact Lineer Collider. We assume that tau-sneutrinos decays in to etextmu pair via RPV interactions. Backgroundless subprocess $e{}^{-}e^{+}rightarrowtilde{ u}bar{tilde{ u}}right
arrowmu^{+}mu^{+}e^{-}e^{-}(mu^{-}mu^{-}e^{+}e^{+})$ is analyzed in details. Achievable limits on $Br,(tilde{ u}_{tau}rightarrowmu e)$ at $3sigma$ and $5sigma$ CL are obtained depending on $tilde{ u_{tau}}$ mass.
In a recent Letter Martinez et al.2011 have argued that the existence of extra three families is still perfectly in accord with the standard model (SM), as long as an additional Higgs doublet is also present. Here we claim that the mentioned accordan
ce can be obtained with less reliance on BSM physics like additional Higgs doublets, but benefiting from Majorana neutrinos is sufficient.
In this study we investigated indirect manifestations of color octet electron at the next generation linear colliders: International Linear Collider (ILC) and Compact Linear Collider (CLIC). Namely, production of two gluons via color octet electron e
xchange is considered. Signal and background analysis have been performed taking into account initial state radiation and beamstrahlung. We show that color octet electron (e_(8)) manifestation will be seen upto M(e_(8))=1.75 TeV and 1.70 TeV at ILC and CLIC with sqrt(s)=0.5 TeV, respectively. CLIC with sqrt(s)=3 TeV will be sensitive upto M(e_(8))=6.88 TeV.
Existence of the fourth family follows from the basics of the Standard Model and the actual mass spectrum of the third family fermions. We discuss possible manifestations of the fourth SM family at existing and future colliders. The LHC and Tevatron
potentials to discover the fourth SM family have been compared. The scenario with dominance of the anomalous decay modes of the fourth family quarks has been considered in details.
