Evidence for neutrino oscillations from the observation of $\\bar{\\nu}_e$ appearance in a $\\bar{\\nu}_\\mu$ beam

A search for ${\\overline{\\ensuremath{\\nu}}}_{\\ensuremath{\\mu}}\\ensuremath{\\rightarrow}{\\overline{\\ensuremath{\\nu}}}_{e}$ oscillations was conducted by the Liquid Scintillator Neutrino Detector at the Los Alamos Neutron Science Center using ${\\overline{\\ensuremath{\\nu}}}_{\\ensuremath{\\mu}}$ from ${\\ensuremath{\\mu}}^{+}$ decay at rest. A total excess of $87.9\\ifmmode\\pm\\else\\textpm\\fi{}22.4\\ifmmode\\pm\\else\\textpm\\fi{}6.0$ events consistent with ${\\overline{\\ensuremath{\\nu}}}_{e}\\stackrel{\\ensuremath{\\rightarrow}}{p}{e}^{+}n$ scattering was observed above the expected background. This excess corresponds to an oscillation probability of $(0.264\\ifmmode\\pm\\else\\textpm\\fi{}0.067\\ifmmode\\pm\\else\\textpm\\fi{}0.045)%,$ which is consistent with an earlier analysis. In conjunction with other known limits on neutrino oscillations, the LSND data suggest that neutrino oscillations occur in the $0.2--10 {\\mathrm{eV}}^{2}{/c}^{4} \\ensuremath{\\Delta}{m}^{2}$ range, indicating a neutrino mass greater than $0.4 \\mathrm{eV}{/c}^{2}.$