相关论文: Diminishing "charginos nearly degenerate with the …
Though LEP II direct searches still cannot exclude a chargino nearly degenerate with the lightest neutralino if its mass is only slightly above half of the Z boson mass and the sneutrino is light, it can be excluded indirectly analyzing…
A search for charginos nearly mass degenerate with the lightest neutralino is performed with the data collected by the ALEPH detector at LEP, at centre-of-mass energies between 189 and 209 GeV, corresponding to an integrated luminosity of…
A search for charginos with masses close to the mass of the lightest neutralino is reported, based on the data collected with the DELPHI detector at LEP from 1995 to 1997 at centre-of-mass energies between 130 and 183 GeV. The signature of…
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…
The search for charginos and neutralinos at LEP2 can become problematic if these particles are almost mass degenerate with the lightest neutralino. Unfortunately this is the case in the region where these particles are higgsino-like. We…
We analyze the LEP constraints from searches for charginos $\chi^{\pm}$ and neutralinos $\chi_i$, taking into account radiative corrections to the relations between their masses and the underlying Higgs-mixing and gaugino-mass parameters…
We review the evaluation of two-body decay modes of charginos in the Minimal Supersymmetric Standard Model with complex parameters (cMSSM). Assuming heavy scalar quarks we take into account all decay channels involving charginos,…
The data collected by DELPHI in 1998 at the centre-of-mass energy of 189 GeV have been used to update the search for charginos nearly mass-degenerate with the lightest supersymmetric particle, which is assumed to be the lightest neutralino.…
Searches for electroweak production of chargino pairs, $\tilde{\chi}^{+}_{1}\tilde{\chi}^{-}_{1}$, and of chargino and next-to-lightest neutralino, $\tilde{\chi}^{\pm}_{1}\tilde{\chi}^{0}_{2}$, are presented. The models explored assume that…
The existence of extra chiral generations with all fermions heavier than $M_Z$ is strongly disfavored by the precision electroweak data. The exclusion of one additional generation of heavy fermions in SUSY extension of Standard Model is…
Bounds on cross section measurements of chargino pair production at LEP yield a bound on the chargino mass. If the GUT relation is assumed, the lightest neutralino must be heavier than $\approx 45 -50\GeV$. If no GUT relation is assumed, no…
We propose an analysis of LEP constraints on radiative neutralino decays into a light gravitino, based on the plane of the Higgs mixing parameter mu and the SU(2) gaugino mass M_2. The preliminary LEP 2W constraints in the (mu, M_2) plane…
A light stop with mass almost degenerate with the lightest neutralino has important connections with both naturalness and dark matter relic abundance. This region is also very hard to probe at colliders. In this paper, we demonstrate the…
We show that in the Minimal Supersymmetric Standard Model, the mass of the lightest neutralino is experimentally unconstrained if the GUT relation between the gaugino mass parameters M_1 and M_2 is dropped. We discuss what the impact of…
We show that the LEP lower bound on the chargino mass, in conjunction with the well motivated theoretical requirement of radiative electroweak symmetry breaking, imply an upper bound on the lightest Higgs boson mass ($m_h\lsim62\GeV$) in a…
We explore modifications to the loop-induced Higgs couplings h\gamma\gamma\ and h\gamma Z from light charginos in the Minimal Supersymmetric Standard Model. When the lightest chargino mass is above the naive LEP bound of order 100 GeV the…
We compute corrections to precision electroweak observables in supersymmetry in the limit that scalar superpartners are very massive and decoupled. This leaves charginos and neutralinos and a Standard Model-like Higgs boson as the only…
We present an up-to-date analysis of the constraints imposed bythe precision data on the ($CP-$ conserving) Two-Higgs-Doublet Model of type II, with emphasis on the possible existence of very light neutral (pseudo)scalar Higgs boson with…
In the framework of the minimal cosmological standard model, the $\Lambda$CDM model, the Dark Matter density is now known with an error of a few percent; this error is expected to shrink even further once PLANCK data are analyzed. Matching…
The large amount of data accumulated at LEP2 by the ALEPH experiment has been used to search for supersymmetric particles. No signal has been found therefore limits have been determined. Within the Constrained Minimal Supersymmetric…