G. Kalbfleisch

Improved experimental limits on the production of magnetic monopoles

We present new limits on low mass accelerator-produced pointlike Dirac magnetic monopoles trapped and bound in matter surrounding the D0 collision region of the Tevatron at Fermilab (experiment E-882). In the context of a Drell-Yan mechanism, we obtain cross section limits for the production of monopoles with magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac charge of the order of picobarns, some 100 times smaller than found in similar previous Fermilab searches. Mass limits inferred from these cross section limits are presented.

Limits on production of magnetic monopoles utilizing samples from the D0 and CDF detectors at the Fermilab Tevatron

We present 90% confidence level limits on magnetic monopole production at the Fermilab Tevatron from three sets of samples obtained from the D0 and CDF detectors each exposed to a proton-antiproton luminosity of

MEASUREMENT OF THE TOP QUARK PAIR PRODUCTION CROSS SECTION IN PP COLLISIONS

\sim175 {pb}^{-1}

Direct and indirect searches for low mass magnetic monopoles

(experiment E-882). Limits are obtained for the production cross-sections and masses for low-mass accelerator-produced pointlike Dirac monopoles trapped and bound in material surrounding the D0 and CDF collision regions. In the absence of a complete quantum field theory of magnetic charge, we estimate these limits on the basis of a Drell-Yan model. These results (for magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac charge) extend and improve previously published bounds.

Measurement of B(Ds+ → μ+νμ)B(Ds+ → φμ+νμ) and determination of the decay constant fDs

We present a measurement of the ttbar production cross section in ppbar collisions at root(s) = 1.8TeV by the D0 experiment at the Fermilab Tevatron. The measurement is based on data from an integrated luminosity of approximately 125 pb^-1 accumulated during the 1992-1996 collider run. We observe 39 ttbar candidate events in the dilepton and lepton+jets decay channels with an expected background of 13.7+-2.2 events. For a top quark mass of 173.3GeV/c^2, we measure the ttbar production cross section to be 5.5+-1.8 pb.

New techniques for emulsion analysis in a hybrid experiment

Recently, there has been renewed interest in the search for low-mass magnetic monopoles. At the University of Oklahoma we are performing an experiment (Fermilab E882) using material from the old D0 and CDF detectors to set limits on the existence of Dirac monopoles of masses of the order of 500 GeV. To set such limits, estimates must be made of the production rate of such monopoles at the Tevatron collider, and of the binding strength of any such produced monopoles to matter. Here we sketch the still primitive theory of such interactions, and indicate why we believe a credible limit may still be obtained. On the other hand, there have been proposals that the classic Euler–Heisenberg Lagrangian together with duality could be employed to set limits on magnetic monopoles having masses less than 1 TeV, based on virtual, rather than real processes. The D0 collaboration at Fermilab has used such a proposal to set mass limits based on the nonobservation of pairs of photons each with high transverse momentum. We critique the underlying theory, by showing that the cross section violates unitarity at the quoted limits and is unstable with respect to radiative corrections. We therefore believe that no significant limit can be obtained from the current experiments, based on virtual monopole processes.

THEORETICAL AND EXPERIMENTAL STATUS OF MAGNETIC MONOPOLES

We have observed

Limit on heavy neutrino in tritium beta decay

23.2 \pm 6.0_{-0.9}^{+1.0}

Charge sharing and resolution studies of double-sided silicon microstripe detectors with boron spray implants

purely-leptonic decays of

Experimental limits on heavy neutrinos in tritium beta decay

D_s^+ ->\mu^+ \nu_\mu