arXiv subjects

F. Franke

Publications and source records attributed to F. Franke.

25 records · Page 2Linked to original sources

arXiv1996

Neutralino mass bounds at the upgraded LEP collider

Assuming that no supersymmetric signature will be found at the upgraded LEP collider we derive lower bounds on the masses of the four neutralinos $\tildeχ_i^0$ in the Minimal Supersymmetric Standard Model (MSSM). We consider the recently published results from the search for the light chargino $\tildeχ^\pm_1$ and the next-to-lightest neutralino $\tildeχ^0_2$ at LEP1.5 and study the consequences of possible future lower $\tildeχ^\pm_1$ and $\tildeχ^0_2$ mass limits between 65 and 95 GeV. For a chargino mass bound of 66.8 GeV at LEP1.5, a massless neutralino is not excluded for $\tanβ< 1.2$. If either $\tanβ> 2.3$ or the gluino mass $m_{\tilde{g}} > 160$ GeV, we find $m_{\tildeχ_1^0} > 28$ GeV. A possible chargino bound $m_{\tildeχ_1^\pm} > 95$ GeV at LEP2 would raise this bound to 31 GeV (for all $\tanβ$) or 44 GeV ($\tanβ> 2$).

hep-ph↗

arXiv1996

Searches For New Physics

Review of prospects for discovery of new physics signals at LEP2. The areas covered include SUSY, exotic fermions, BESS models, leptoquarks, virtual effects and CP violating observables.

hep-ph↗

arXiv1995

Neutralinos and Higgs Bosons in the Next-To-Minimal Supersymmetric Standard Model

The purpose of this paper is to present a complete and consistent list of the Feynman rules for the vertices of neutralinos and Higgs bosons in the Next-To-Minimal Supersymmetric Standard Model (NMSSM), which does not yet exist in the literature. The Feynman rules are derived from the full expression for the Lagrangian and the mass matrices of the neutralinos and Higgs bosons in the NMSSM. Some crucial differences between the vertex functions of the NMSSM and the Minimal Supersymmetric Standard Model (MSSM) are discussed.

hep-ph↗

arXiv1995

Production and Decay of Neutralinos in the Next-To-Minimal Supersymmetric Standard Model

Within the framework of the Next-To-Minimal Supersymmetric Standard Model (NMSSM) we study neutralino production $e^+e^- \longrightarrow \tildeχ^0_i \tildeχ^0_j$ ($i,j=1,\ldots ,5$) at center-of-mass energies between 100 and 600 GeV and the decays of the heavier neutralinos into the LSP plus a fermion pair, a photon or a Higgs boson. For representative gaugino/higgsino mixing scenarios, where the light neutralinos have significant singlet components, we find some striking differences between the NMSSM and the minimal supersymmetric model. Since in the NMSSM neutralino and Higgs sector are strongly correlated, the decay of the second lightest neutralino into a Higgs boson and the LSP often is kinematically possible and even dominant in a large parameter region of typical NMSSM scenarios. Also, the decay rates into final states with a photon may be enhanced.

hep-ph↗

arXiv1995

Mass Bounds for the Neutral Higgs Bosons in the Next-To-Minimal Supersymmetric Standard Model

In the Next--To--Minimal Supersymmetric Standard Model (NMSSM), the Higgs and neutralino/chargino sectors are strongly correlated by four common parameters at tree level. Therefore we analyze the experimental data from both the search for Higgs bosons as well as for neutralinos and charginos at LEP 100 in order to constrain the parameter space and the masses of the neutral Higgs particles in the NMSSM. We find that small singlet vacuum expectation values are ruled out, but a massless neutral Higgs scalar and pseudoscalar is not excluded for most of the parameter space of the NMSSM. Improved limits from the neutralino/chargino search at LEP 200, however, may lead to nonvanishing lower Higgs mass bounds.

hep-ph↗

arXiv1995

Production of Supersymmetric Higgs Bosons at LEP x LHC

Within the Minimal Supersymmetric Standard Model (MSSM), we study the production of the neutral scalar and pseudoscalar as well as the charged Higgs bosons together with fermions or sfermions in deep inelastic $ep$ scattering at $\sqrt{s}=1.6$ TeV. We focus on the parameter space where a Higgs particle is likely to be invisible at LEP2 and LHC. Although we choose gaugino/higgsino mixing scenarios that maximize the corresponding production rates we find only for the production of the scalar Higgs bosons in the non-supersymmetric channels non-negligible cross sections of the order of $10^2$ fb.

hep-ph↗

arXiv1994

Neutralino Mass Bounds in the Next-To-Minimal Supersymmetric Standard Model

We analyze the experimental data from the search for new particles at LEP 100 and obtain mass bounds for the neutralinos of the Next--To--Minimal Supersymmetric Standard Model (NMSSM). We find that for $\tanβ\gsim 5.5$ a massless neutralino is still possible, while the lower mass bound for the second lightest neutralino corresponds approximately to that for the lightest neutralino in the Minimal Supersymmetric Standard Model (MSSM).

hep-ph↗