Evidence for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mover><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover><mml:mrow><mml:mi>μ</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mo>→</mml:mo><mml:mrow><mml:msub><mml:mover><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mi>¯</mml:mi></mml:mrow></mml:mover><mml:mrow><mml:mi mathvariant="italic">e</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>Oscillations from the LSND Experiment at the Los Alamos Meson Physics Facility

Abstract

A search for $\\bar\\nu_{\\mu}\\to \\bar\\nu_{e}$ oscillations has been conducted\nat the Los Alamos Meson Physics Facility by using $\\bar\\nu_\\mu$ from $\\mu^+$\ndecay at rest. The $\\bar\\nu_e$ are detected via the reaction $\\bar\\nu_e\\,p\n\\rightarrow e^{+}\\,n$, correlated with a $\\gamma$ from $np\\rightarrow d\\gamma$\n($2.2\\,{\\rm MeV}$). The use of tight cuts to identify $e^+$ events with\ncorrelated $\\gamma$ rays yields 22 events with $e^+$ energy between 36 and\n$60\\,{\\rm MeV}$ and only $4.6 \\pm 0.6$ background events. A fit to the $e^+$\nevents between 20 and $60\\,{\\rm MeV}$ yields a total excess of\n$51.8^{+18.7}_{-16.9} \\pm 8.0$ events. If attributed to $\\bar \\nu_\\mu\n\\rightarrow \\bar \\nu_e$ oscillations, this corresponds to an oscillation\nprobability of ($0.31^{+0.11}_{-0.10} \\pm 0.05$)\\%.\n