Search for the neutral Higgs Boson from Z0 decay in the Higgs mass range between 11 and 24 GeV

A search for the neutral Higgs boson in the mass range above 11 GeV (above the threshold), using the process Z0→H0e+e−, Z0→H0μ+μ− and , is performed on data collected by the ALEPH detector corresponding to about 25 000 events of Z0→ hadrons. Combining all these processes, the mass range excluded is 11 GeV at 95% CL. Together with a previously published result from ALEPH, the mass range excluded is 32 MeV to 24 GeV at 95% CL. This result also extends the excluded mass region for neutral Higgs bosons from supersymmetry

A Study of single and multi - photon production in e+ e- collisions at center-of-mass energies of 130-GeV and 136-GeV

The production of final states involving one or more energetic photons from e+e- collisions at high energies is studied using data collected by the ALEPH detector at LEP. The data consist of two samples of 2.9 pb-1 each, recorded at centre-of-mass energies of 130 GeV and 136 GeV. The data are in agreement with the predictions of the Standard Model. From an analysis of two-photon final states new limits are placed on the parameters of models involving contact interactions and excited electrons. The 95% confidence level lower limits on the QED cut-off parameters are found to be 169 and 132 GeV respectively

Search for excited leptons in Z0 decay

We have looked for evidence of excited lepton production in Z0 decay observed in the ALEPH detector at LEP. We find no ℓℓγγ events and set new limits at 95% CL on ℓ∗ masses at 44.6, 44.6 and 41.2 GeV/c2 for respectively. Observed events in the ℓℓγ channels are consistent with radiative effects and we set limits for the first time on the coupling for ℓ∗ masses in the range up to 86 GeV/c2

Measurement of charge asymmetry in hadronic Z decays

A significant charge asymmetry is observed in the hadronic Z decays with the ALEPH detector at LEP. The asymmetry expressed in terms of the difference in momentum weighted charges in the two event hemispheres is measured to be −= −0.0084±0.0015 (stat.) ±0.0004 (exp. sys.). In the framework of the standard model this can be interpreted as a measurement of the effective electroweak mixing angle, sin2Ow (Mz2=0.2300±0.0034 (stat.) ±0.0010 (exp. sys.) ±0.0038 (theor. sys.) or of the ratio of the vector to axual- vector coupling costants of the electron, gvegAe=+0.073±0.024