相关论文: Signals for Neutralino Box Effects at LEP2
Observational evidences of nonzero neutrino masses and the existence of dark matter request physics beyond standard model. A model with extra scalars and leptonic vector-like fermions is introduced. By imposing a Z_2 symmetry, the neutrino…
This report summarizes the results of the two-fermion working group of the LEP2-MC workshop, held at CERN from 1999 to 2000. Recent developments in the theoretical calculations of the two fermion production process in the electron-positron…
We consider chargino-neutralino production, $\tilde{\chi}_2^0 \tilde{\chi}_1^\pm \to (h \tilde{\chi}_1^0)(W^\pm \tilde{\chi}_1^0)$, which results in Higgs boson final states that subsequently decay (inclusively) to leptons (either…
We determine the radiative corrections to the masses of the gauginos and Higgsinos in the MSSM, including all sectors of the theory in a one-loop calculation in the on-mass-shell renormalization scheme. We find that a gluino which is…
A search for charginos and neutralinos, predicted by supersymmetric theories, is performed using a data sample of 182.1 pb-1 taken at a centre-of-mass energy of 189 GeV with the OPAL detector at LEP. No evidence for chargino or neutralino…
We report the result of a search for charginos and neutralinos, in e+e- collisions at 189 GeV centre-of-mass energy at LEP. No evidence for such particles is found in a data sample of 176 pb^{-1}. Improved upper limits for these particles…
Currently popular search strategies for supersymmetric particles may be significantly affected due to relatively light sneutrinos which decay dominantly into invisible channels. In certain cases the second lightest neutralino may also decay…
The results of searches for selectrons, charginos and neutralinos performed with the data collected by the ALEPH detector at LEP at centre-of-mass energies up to 209 GeV are interpreted in the framework of the Minimal Supersymmetric…
We consider the effects of heavy Majorana neutrinos N with sub-TeV masses. We argue that the mere presence of these particles would be a signal of physics beyond the minimal seesaw mechanism and their interactions are, therefore, best…
We examine indirect signals produced by neutralino self-annihilations, in the galactic halo or inside celestial bodies, in the frame of an effective MSSM model without gaugino-mass unification at a grand unification scale. We compare our…
We search for inclusive high $E_T$ diphoton events with large missing transverse energy in $p\bar{p}$ collisions at $\sqrt{s}$=1.8 TeV. Such events are expected from pair production of charginos and neutralinos within the framework of the…
A search was performed for charginos with masses close to the mass of the lightest neutralino in e+e- collisions at centre-of-mass energies of 189-209 GeV recorded by the OPAL detector at LEP. Events were selected if they had an observed…
We revisit the current experimental bounds on fourth-generation Majorana neutrino masses, including the effects of right handed neutrinos. Current bounds from LEPII are significantly altered by a global analysis. We show that the current…
We examine for representative gaugino-higgsino mixing scenarios sneutrino-neutralino and sneutrino-chargino production in deep inelastic ep-scattering at the cm-energy of 1.8 TeV. The cross sections for sneutrino-chargino production are…
The tree-level-massless gaugino scenario predicts that the lighter chargino mass is less than m_W and that gluino and lightest neutralino masses are $\lsi 1$ GeV. In this case the dominant decay mode of charginos and non-LSP neutralinos is…
We derive the low-energy electroweak effective lagrangian for the case of additional heavy, unmixed, sequential fermions. Present data still allow for the presence of a new quark and/or lepton doublet with masses greater than $M_Z/2$,…
We derive the low-energy electroweak effective lagrangian for the case of additional heavy, unmixed, sequential fermions. Present LEP1 data still allow for the presence of a new quark and/or lepton doublet with masses greater than $M_Z/2$,…
In the context of the Einstein-Cartan-Dirac model, where the torsion of the space-time couples to the axial currents of the fermions, we study the effects of this quantum-gravitational interaction on a massless neutrino beam crossing…
We study the process e^{-} e^{+} -> chi^0_1 chi^0_2 with the subsequent decay chi^0_2 -> chi^0_1 l^{+} l^{-} taking into account the complete spin correlations. We give the analytical formulae for the differential cross section and present…
In the framework of a particular supergravity model which provides a natural solution to the $\mu$--problem we show how the discovery of a chargino at LEP2 and the measurement of its mass and production cross--section, together with the…