Search for Chargino and Neutralino Production at sqrt{s} = 170 and 172 GeV at LEP

Searches for a scalar top quark and a scalar bottom quark have been performed using a total data sample of 56.8 pb-1 at a centre-of-mass energy of 183 GeV collected with the OPAL detector at LEP. No candidate events were observed. Combining this result with those obtained at lower centre-of-mass energies, the 95% C.L. lower limit on the scalar top quark mass is 85.0 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top qua...

Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 438 pb-1 at centre-of-mass energies of sqrt(s) = 192 - 209 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 97.6 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. When the scalar top quark decouples from t...

Searches for pair production of squarks, sleptons, charginos, and neutralinos are performed with the data collected by the ALEPH detector at LEP at centre-of-mass energies from 188.6 to 201.6 GeV. No evidence for any such signals is observed in a total integrated luminosity of about 410pb-1. The negative results of the searches are translated into exclusion domains in the space of the relevant MSSM parameters, which improve significantly on the constraints set previously. Und...

We show that LEPII will either discover charginos and neutralinos, or enable a very stringent upper limit to be placed on $\tan \beta$ as a function of the gluino mass. The only assumption we make is the existence of some unified model which breaks down to the minimal supersymmetric standard model below the unification scale. In such a framework we discuss how the discovery of a chargino at LEPII and the measurement of its mass and production cross-section, together with the ...

Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 182 pb-1 at a centre-of-mass energy of 189 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 90.3 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. In the worst case, when the scalar top quark decouples fro...

Searches for pair-produced charginos, neutralinos and scalar fermions decaying via R-parity violating / /\' and /\'' couplings with the OPAL detector at LEP are presented at sqrt(s)=189 GeV. Partial updates using data up to the highest energies of LEP, sqrt(s)=209 GeV, are also given.

We have searched for chargino-neutralino production (\chichi) in 1.8 TeV \ppb\sp collisions, followed by their leptonic decays \chione\dk\chizero\lnu\psp and \chitwo\dk\chizero\lplm. These trilepton events are expected within a framework of the Minimal Supersymmetric Standard Model (MSSM). In a 19.1 pb$^{-1}$ data sample collected with the Collider Detector at Fermilab, no trilepton events were observed. Upper limits on $\sigma(\ppb\dk\chichi)\cdot BR(\chichi\dk 3 \ell + X)$ ...

Searches for pair-produced charginos and neutralinos with R-parity violating decays have been performed using a data sample corresponding to an integrated luminosity of 56 pb-1 collected with the OPAL detector at LEP at a centre-of-mass energy of 183 GeV. An important consequence of R-parity violation is that the lightest supersymmetric particle becomes unstable. The searches have been performed under the assumptions that the lightest supersymmetric particle promptly decays a...

We present a search for the associated production of charginos and neutralinos in p-pbar collisions at 1.96 TeV. The data were collected at the Collider Detector at Fermilab (CDF II) and correspond to integrated luminosities between 0.7 and 1.0 fb-1. We look for final states with one high pT electron or muon, and two additional leptons. Our results are consistent with the standard model expectations, and we set limits on the cross section as a function of the chargino mass in...

A search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Several scenarios based on simplified models are considered. These include the associated production of the next-to-lightest neutralino and the lightest chargino, followed...