SNO+

Abstract:

Bd0-B̄d0 oscillations are observed in "self-tagged" samples of partially reconstructed B mesons decaying into a lepton and a charmed meson collected in pp̄ collisions at √s=1.8 TeV. A flavor tagging technique is employed which relies upon the correlation between the flavor of B mesons and the charge of a nearby particle. We measure the flavor oscillation frequency to be Δmd=0.471-0.068+0.078±0.034 ps-1. The tagging method is also demonstrated in exclusive samples of Bu+→J/ψK+ and Bd0→J/ψK*0(892), where similar flavor-charge correlations are observed. The tagging characteristics of the various samples are compared with each other, and with Monte Carlo simulations.

Abstract:

The lifetime of the BS0 meson is measured using the semileptonic decay BS0→DS-l+νX. The data sample consists of about 110 pb-1 of pp̄ collisions at √s=1.8 TeV collected by the CDF detector at Fermilab. Four different DS- decay modes are reconstructed resulting in approximately 600 DS-l+ signal events. The BS0 meson lifetime is determined to be τ(BS0)=(1.36±0.09-0.05+0.06) ps, where the first and second uncertainties are statistical and systematic, respectively. The BS0 meson decay length distribution is examined for a lifetime difference ΔΓ/Γ between the two mass eigenstates of the BS0 meson. An upper limit of ΔΓ/Γ<0.83 is set at the 95% confidence level.

Abstract:

The results of recent studies which seek to probe fundamental aspects of astrophysics using TeV gamma-ray observations of active galactic nuclei (AGN) are presented. These analyses take advantage of both spectral and temporal information together with the unique combination of the very high energies and large distance scales involved. The next generation of instruments currently planned are expected to make substantial improvements in the study of such phenomena. © 1999 Elsevier Science B.V. All rights reserved.

Abstract:

We have used data from a TeV gamma-ray flare associated with the active galaxy Markarian 421 to place bounds on the possible energy dependence of the speed of light in the context of an effective quantum gravitational energy scale. Recent theoretical work suggests that such an energy scale could be less than the Planck mass and perhaps as low as 10^16 GeV. The limits derived here indicate this energy scale to be in excess of 4×106 GeV for at least one approach to quantum gravity in the context of D-brane string theory. To the best of our knowledge this constitutes the first convincing limit on such phenomena in this energy regime. © 1999 The American Physical Society.