Limits on Production of Magnetic Monopoles Utilizing Samples from the DO and CDF Detectors at the 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 $\sim175 {pb}^{-1}$ (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.Comment: 18 pages, 17 figures, REVTeX

Improved Experimental Limits on the Production of Magnetic Monopoles

We present new limits on low mass accelerator-produced point-like Dirac magnetic monopoles trapped and bound in matter surrounding the D\O 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 hundred times smaller than found in similar previous Fermilab searches. Mass limits inferred from these cross section limits are presented.Comment: 5 pages, 4 eps figures, REVTe

Antimatter in the Universe

Cosmological models which predict a large amount of antimatter in the Universe are reviewed. Observational signatures and searches for cosmic antimatter are briefly considered. A short discussion of new long range forces which might be associated with matter and antimatter is presented.Comment: 17 pages + 2 figure

Possible Effects of Quantum Mechanics Violation Induced by Certain Quantum Gravity on Neutrino Oscillations

In this work we tried extensively to apply the EHNS postulation about the quantum mechanics violation effects induced by the quantum gravity of black holes to neutrino oscillations. The possibilities for observing such effects in the neutrino experiments (in progress and/or accessible in the near future) were discussed. Of them, an interesting one was outlined specially.Comment: 18 pages, 0 figure, (1 REVTeX file

A Prototype Detector for Directional Measurement of the Cosmogenic Neutron Flux

This paper describes a novel directional neutron detector prototype. The low pressure time projection chamber uses a mix of helium and CF4 gases. The detector reconstructs the energy and angular distribution of fast neutron recoils. This paper reports results of energy calibration using an alpha source and angular reconstruction studies using a collimated neutron source. The best performance is obtained with a 12.5% CF4 gas mixture. At low energies the target for fast neutrons transitions is primarily helium, while at higher energies, the fluorine contributes as a target. The reconstruction efficiency is both energy and target dependent. For neutrons with energies less than 20 MeV, the reconstruction efficiency is ~40% for fluorine recoils and ~60% for helium recoils.Comment: final versio

Gauge Singlet Scalars as Cold Dark Matter

In light of recent interest in minimal extensions of the Standard Model and gauge singlet scalar cold dark matter, we provide an arXiv preprint of the paper, published as Phys.Rev. D50 (1994) 3637, which presented the first detailed analysis of gauge singlet scalar cold dark matter.Comment: 37 pages, 11 figures, LaTe

Neutralino properties in the light of a further indication of an annual modulation effect in WIMP direct search

We demonstrate that the further indication of a possible annual modulation effect, singled out by the DAMA/NaI experiment for WIMP direct detection, is widely compatible with an interpretation in terms of a relic neutralino as the major component of dark matter in the Universe. We discuss the supersymmetric features of this neutralino in the Minimal Supersymmetric extension of the Standard Model (MSSM) and their implications for searches at accelerators.Comment: 15 pages, ReVTeX, 9 figures (included as PS files

Neutrino mass matrix with U(2) flavor symmetry and neutrino oscillations

The three neutrino mass matrices in the $SU(5)\times U(2)$ model are studied focusing on the neutrino oscillation experiments. The atmospheric neutrino anomaly could be explained by the large $\nu_{\mu} - \nu_{\tau}$ oscillation. The long baseline experiments are expected to detect signatures of the neutrino oscillation even if the atmospheric neutrino anomaly is not due to the neutrino oscillation. However, the model cannot solve the solar neutrino deficit while it could be reconciled with the LSND data.Comment: 12 pages, LaTex file, to be published in PR

Superheated Microdrops as Cold Dark Matter Detectors

It is shown that under realistic background considerations, an improvement in Cold Dark Matter sensitivity of several orders of magnitude is expected from a detector based on superheated liquid droplets. Such devices are totally insensitive to minimum ionizing radiation while responsive to nuclear recoils of energies ~ few keV. They operate on the same principle as the bubble chamber, but offer unattended, continuous, and safe operation at room temperature and atmospheric pressure.Comment: 15 pgs, 4 figures include