Observation of tungsten ---> muon-neutrino decays in proton-antiproton collisions at sqrt. s = 1.8 TeV

Abstract

The inclusive spectrum of charged particles resulting from the decays of stopped positively charged kaons, produced in proton-antiproton annihilations at rest, has been measured with good momentum resolution $(\delta p/p$ = 1.5%) and high statistics ($\sim$300,000 potential decays). The data were obtained with the Experiment PS183 magnetic pair spectrometer at LEAR, the Low Energy Antiproton Ring located at CERN, during two running periods: May 1985 and July-August 1986. Peaks corresponding to the reactions $K\sp+\to\pi\sp+\pi\sp0$ and $K\sp+\to\mu\sp+\nu\sb\mu$ have been measured with high precision resulting in a determination of the relative branching ratio $K\sp+\to\pi\sp+\pi\sp0$/K$\sp+\to\mu\sp+\nu\sb\mu$ =.3329 $\pm$.0047 (statistical) $\pm$.0017 (systematic). This measurement represents the most precise determination of this ratio to date.