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We study the pair production of fourth generation neutrinos from the decay of an on-shell Higgs produced by gluon fusion. In a fourth generation scenario, the Higgs branching fraction into fourth generation neutrinos may be quite large. In the case that the unstable heavy neutrinos are a mixed Majorana and Dirac state, neutrinos pair-produced from Higgs decay will yield a substantial number of like-sign dilepton events. In this article we use inclusive like-sign dilepton searches from hadron colliders to constrain the theoretical parameter space of fourth generation leptons.
We derive constraints on the relic abundance of a generic particle of mass $sim~1-10^{14}$ TeV which decays into neutrinos at cosmological epochs, using data from the Frejus and IMB nucleon decay detectors and the Flys Eye air shower array. The lifet
Searches for heavy Majorana neutrinos in B- decays in final states containing hadrons plus a mu- mu- pair have been performed using 0.41/fb of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. The
Unparticles ($U$) interact weakly with particles. The direct signature of unparticles will be in the form of missing energy. We study constraints on unparticle interactions using totally invisible decay modes of $Z$, vector quarkonia $V$ and neutrino
We recompute the invisible Higgs decay width arising from Higgs-graviscalar mixing in the ADD model, comparing the original derivation in the non-diagonal mass basis to that in a diagonal mass basis. The results obtained are identical (and differ by
LHC searches for non-standard Higgs bosons decaying into tau lepton pairs constitute a sensitive experimental probe for physics beyond the Standard Model (BSM), such as Supersymmetry (SUSY). Recently, the limits obtained from these searches have been