Published: 2007
Total Pages: 269
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The evidence is compelling that neutrinos undergo flavor change as they propagate. In recent years, experiments have observed this phenomenon of neutrino oscillations using disparate neutrino sources: the sun, fission reactors, accelerators, and secondary cosmic rays. The standard model of particle physics needs only simple extensions - neutrino masses and mixing - to accommodate all neutrino oscillation results to date, save one. The 3.8?-significant $ar{v}$e excess reported by the LSND collaboration is consistent with $ar{v}$? →$ar{v}$e oscillations with a mass-squared splitting of ?m2 ̃1 eV2. This signal, which has not been independently verified, is inconsistent with other oscillation evidence unless more daring standard model extensions (e.g. sterile neutrinos) are considered.