arXiv subjects
Publications and source records attributed to Maria Krawczyk.
Present data do not rule out a light neutral Higgs particle with mass below 40--50 GeV in the framework of 2HDM with $ tan β\sim $ 20-30. The promising possibility of searching for a light Higgs particle in such a scenario in photoproduction at HERA collider is discussed. For the MSSM there is only a very small chance to observe the Higgs sector, and only for limited mass range $\sim$ 45-50 GeV and with large $ tan β$.
Constraints on the general 2HDM ("Model II") are obtained from the existing $(g-2)_μ$ data including limits on Higgs bosons masses from LEP I data. We consider separately two cases: with a light scalar $h$ and with a light pseudoscalar $A$, assuming ${M_{h}+M_{A}} \ge {M_{Z}}$. The charged Higgs contribution is also included. It is found that already the present $(g-2)_μ$ data improve limits obtained recently by ALEPH collaboration on $\tb$ for the mass of the pseudoscalar below $ \mr$ 2 GeV. The improvement in the accuracy by factor 20 in the forthcoming E821 experiment may lead to more stringent, than provided by ALEPH group, limits up to $M_A\sim$ 30 GeV if the mass difference between $h$ and $A$ is $\sim M_Z$. Similar results should hold for a light scalar scenario as well.
Present data do not rule out the light neutral Higgs particle $h$ or $A$ in the framework of the general 2HDM. The discovery reach/exclusion limits of the Yukawa process $Z\rightarrow f {\bar f} h/A$, ($f= b$ quark or $τ$ lepton) at LEP I and of the gluon-gluon fusion at HERA is discussed. In addition the possible search for very light Higgs particle in $γγ$ fusion at low energy NLC is described.
A light neutral Higgs boson in the framework of the general two Higgs doublet model (2HDM) is not excluded by existing data. We point out that it can be looked for at the proposed low energy $γγ$ collider. Failure to detect one may lead to important limits on the parameters of the general 2HDM.
We investigate the production of Higgs bosons $A/h$ via the Yukawa process $Z\ra f\bar{f} \ra f\bar{f} A/h $ taking into account QCD corrections and fermion mass effects. We estimate the discovery reach of this process and/or bounds on the parameter space of two-Higgs doublet models which can be derived from the analysis of $b {\bar b} τ^+ τ^-$ events at LEP1. These limits have important consequences for extended models of electroweak interactions and their experimental verification/improvement are welcome.