D. Casper

We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{\leftrightarrow}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ oscillations with ${sin}^{2}2\ensuremath{\theta}>0.82$ and $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}<\ensuremath{\Delta}{m}^{2}<6\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}3}\mathrm{eV}{}^{2}$ at 90% confidence level.

This biennial Review summarizes much of Particle Physics. Using data from previous editions plus new measurements from papers we list evaluate and average measured properties of gauge bosons leptons quarks mesons and baryons. We also summarize searches for hypothetical particles such as Higgs bosons heavy neutrinos and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables gures formulae and reviews of topics such as the Standard Model particle detectors probability and statistics. Among the reviews are many that are new or heavily revised including those on neutrino mixing CP violation in K D and B mesons Vcb the new exotic  particle extra dimensions grand unified theories cosmic background radiation dark matter cosmological parameters and big bang cosmology. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables listings and reviews and errata are also available on the Particle Data Group website https://pdg.lbl.gov.

A burst of eight neutrino events preceding the optical detection of the supernova in the Large Magellanic cloud has been observed in a large underground water Cherenkov detector. The events span an interval of six seconds and have visible energies in the range 20--40 MeV.