Related papers: Single-photon signal from neutralinos at LEP2
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…
A search for charginos and neutralinos, predicted by supersymmetric theories, has been performed using a data sample of 57 pb-1 at centre-of-mass energies of 181-184 GeV taken with the OPAL detector at LEP. No evidence for chargino or…
In view of the latest LEP data we consider the effects of charginos and neutralinos on the two-photon and bbbar signatures of the Higgs at the LHC. Assuming the usual GUT inspired relation between M_1 and M_2 we show that there are only…
Relatively light sneutrinos which are experimentally allowed and are not theoretically disfavoured may significantly affect the currently popular search strategies for supersymmetric particles by decaying dominantly into an invisible…
We discuss associated neutralino production e^+ e^- --> \tilde{\chi}^0_1 \tilde{\chi}^0_2 with both beams polarized in the MSSM, NMSSM and an E_6 model. It is shown that neutralinos with a large singlino component can be produced at a high…
Charginos $\chi_1^\pm$ are expected to be the lightest observable supersymmetric particles in many supersymmetric models. We present a procedure which will allow to determine the chargino mixing angles and, subsequently, the fundamental…
We calculate the event rates for the Standard Model production of two photons plus missing mass through the process electron positron to gamma gamma nu nubar, where nu is any of the three neutrino flavors, at LEP energies. This process can…
We discuss the pair production of charginos in collisions of polarized photons $\gamma\gamma \to \tilde{\chi}_i^+ \tilde{\chi}_i^-$, ($i=1,2$) and the subsequent leptonic decay of the lighter chargino $\tilde{\chi}_1^+ \to \tilde{\chi}_1^0…
We consider neutralino production and decay e^+e^ --> chi^0_i chi^0_j, chi^0_j --> chi^0_1 f \bar{f} at a linear collider with transverse e^+ and e^- beam polarization. We propose CP asymmetries by means of the azimuthal distribution of the…
The chargino $\tilde{\chi}^\pm_{1,2}$ system can be reconstructed completely in $e^+e^-$ collisions. By measuring the total cross sections and the asymmetries with polarized beams in $e^+e^-\to\tilde{\chi}_i^+ \tilde{\chi}_j^- [i,j=1,2]$,…
Light gravitino productions in association with a neutralino (selectron) in e^+e^- (e^-\gamma) collisions are restudied in a scenario that the lightest supersymmetric particle is a gravitino and the produced neutralino (selectron) promptly…
In an R-parity violating supersymmetric scenario, the lightest neutralino $\tilde \chi^0_1$ is no longer a stable particle. We calculate the branching ratio for the decay mode $\tilde \chi^0_1 \longrightarrow \nu \gamma$ which occurs at the…
Working within the framework of the minimal supergravity model with gauge coupling unification and radiative electroweak symmetry breaking (SUGRA), we map out regions of parameter space explorable by experiments at LEP2, for center of mass…
We consider analysis targets at the International Linear Collider in which only a single photon can be observed. For such processes, we have developed a method which uses likelihood distributions using the full event information (photon…
We study the production and decay of heavy selectrons in the electron-photon mode of a linear collider of the next generation. The standard model backgrounds can be substantially reduced by appropriate kinematical cuts. As a consequence,…
We study the production of neutralinos and charginos at LEP and at a linear collider in the case of spontaneously broken R-parity. We first investigate the constraints on the single neutralino and chargino production from the LEP 1…
During the LEP2 operation, the 4 LEP experiments have collected data at centre-of-mass energies up to 209 GeV. Those data have been analysed in the search of charginos, neutralinos and sfermions in the framework of the Minimal…
We investigate a scenario inspired by natural supersymmetry, where neutrino data is explained within a low-scale seesaw scenario. For this the Minimal Supersymmetric Standard Model is extended by adding light right-handed neutrinos and…
We explore the techniques, cross sections and expected signal significance for detecting invisible and almost invisible particles at LEP2 and the NLC by means of a hard photon tag. Examples from supersymmetry include the lightest chargino…
In the framework of gauge-mediated supersymmetry breaking models pair production of the lightest neutralinos, scalar leptons, or charginos at LEPII gives rise to interesting signals involving multilepton final states and missing energy. In…