Standard Model Production Research Articles

Determiningtanβfrom the SUSY Higgs sector at futuree+e−colliders

We examine the prospects for determining $\mathrm{tan}\ensuremath{\beta}$ from heavy Higgs scalar production in the minimal supersymmetric standard model at a future ${e}^{+}{e}^{\ensuremath{-}}$ collider. Our analysis is independent of assumptions of parameter unification, and we consider general radiative corrections in the Higgs sector. Bounds are presented for $\sqrt{s}=500\mathrm{GeV}$ and 1 TeV, several Higgs boson masses, a variety of integrated luminosities and $b$-tagging efficiencies, and in scenarios with and without supersymmetric decays of the Higgs bosons. We find stringent constraints for $3\ensuremath{\lesssim}\mathrm{tan}\ensuremath{\beta}\ensuremath{\lesssim}10$ and, for some scenarios, also interesting bounds on high $\mathrm{tan}\ensuremath{\beta}$ through ${\mathrm{tbH}}^{\ifmmode\pm\else\textpm\fi{}}$ production. These bounds imply that simple Yukawa unifications may be confirmed or excluded. Implications for soft scalar mass determination and top squark parameters are also discussed.

CP violation beyond the standard model and tau pair production in e+e− collisions

We show that the CP-violating dipole form factors of the tau lepton can be of the order of α π in units of the length scale set by the inverse Z boson mass. We propose a few observables which are sensitive to these form factors at LEP2 and higher e +e − collision energies.

Heavy-lepton production in the minimal supersymmetric standard model.

We study the production of a charged-heavy-lepton pair considering the minimal supersymmetric standard model. We show that the cross section for the process $\mathrm{pp}\ensuremath{\rightarrow}\mathrm{gg}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ is enhanced for large values of the ratio between the two-Higgs-doublet vacuum expectation values, in comparison with the standard model result. The gluon fusion mechanism is the most important contribution to the lepton pair production for ${M}_{\ensuremath{\ell}}g50$ GeV.

Search for the top quark in the reaction p-barp-->electron+jets at sqrt s =1.8 TeV.

A search for the top quark in p¯p collisions at a center-of-mass energy of 1.8 TeV using the Collider Detector at Fermilab is described. A study of events selected by requiring an energetic electron, missing transverse energy, and two or more jets excludes at 95% confidence level the standard-model production and decay of tt¯ pairs if the top-quark mass is between 40 and 77 GeV/c2. The observed electron + multijet data are consistent with W-boson production.Received 13 October 1989DOI:https://doi.org/10.1103/PhysRevLett.64.142©1990 American Physical Society