相关论文: Signals for Neutralino Box Effects at LEP2
If a light gaugino sector exists in the supersymmetric standard model then the mass of lightest neutralino may be of the order of 1 GeV or less. As a consequence of neutral flavor violation in supersymmetric theories $B_s$-meson may decay…
The weak kaon production off the nucleon induced by neutrinos and antineutrinos is studied at low and intermediate energies of interest for some ongoing and future neutrino oscillation experiments. We develop a microscopical model based on…
Within a wide class of models, the LEP2 lower limit of 95 GeV on the chargino mass implies gluinos are heavier than $\sim$300 GeV. In this case electroweak $\tw_1\twb_1$ and $\tw_1\tz_2$ production are the dominant SUSY processes at the…
With an effective Lagrangian approach, we analyze several NN \to NN\pi\pi channels by including various resonances with mass up to 1.72 GeV. For the channels with the pion pair of isospin zero, we confirm the dominance of N*(1440)\to…
We study the muon $(g-2)_{\mu}$ anomaly in light of neutralino dark matter and the LHC. We scan the MSSM parameters relevant to $(g-2)_{\mu}$ and focus on three distinct cases with different neutralino compositions. We find that the…
Light gluinos have been suggested in order to reconcile $\alpha_s$ determinations from low energy deep inelastic experiments with those inferred from LEP measurements. {}From this hypothesis then one expects, in unified N=1 supergravity…
We study the effects induced by new neutral fermions below their mass threshold, due to their possible mixing with the standard neutrinos. We use as experimental constraints the recent results on lepton universality, together with the…
A search for charginos and neutralinos, predicted by supersymmetric theories, has been performed using a data sample of 10.3 pb^-1 at centre-of-mass energies of sqrt(s) = 170 and 172 GeV with the OPAL detector at LEP. No evidence for these…
We examine the possibility that SUSY particles are light, i.e. have a mass just beyond the final kinematical reach of LEP2. In this case, even if light particles are not directly detected, their virtual effects are enhanced by a ``close to…
We present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon-sneutrinos in the channels smuon->neutralino_1 muon, smuon->neutralino_2 muon, and muon-sneutrino->chargino muon. We analyzed…
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…
We explore the effects of a heavy fermion doublet in a simplified version of the standard electroweak theory. We integrate out the doublet and compute the exact effective energy functional of spatially varying gauge and Higgs fields. We…
We have made a detailed study of the signals produced at LEP-2 from charged scalar bosons whose dominant decay channels are into four fermions. The event rates as well as kinematics of the final states are discussed when such scalars are…
The ongoing searches for Higgs-boson signals in data taken at the CERN LHC and the Fermilab Tevatron crucially rely on the decay channels H -> Z l l and H -> W l nu. We present a precision study of the partial widths of these decay channels…
In the energy region of LEP2 and above, four fermion final states in e+e- collisions can be produced by Feynman diagrams involving two, one or zero resonant bosons...
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…
We study the effect of the neutralino polarization in a squark cascade decay $\tilde{q} \to q \tilde{\chi}^0_2 \to q l^\pm \tilde{l}^\mp \to q l^\pm \tilde{l}^\mp \to q l^\pm l^\mp \tilde{\chi}^0_1$. Charge asymmetry in the lepton-jet…
We calculate the 1-loop $\gamma Z$ box-graph correction to electron-quark scattering at low energy and low momentum transfer. Both electron and quark masses are kept non-zero. From our result, we extract coupling constants for the…
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…
We examine the production and the decay modes of neutralinos and charginos in a softly-broken supersymmetric model with an extra Abelian symmetry U(1)'. We perform the study in a U(1)' model with a secluded sector, where the tension between…