Study of theK+Decay

Abstract

Some properties of the various decay modes of $K^{+}$ mesons have been studied with hodoscope scintillation counters. $122 K_{\mu 3}$ events were identified in the high-energy end of the muon energy spectrum from 115±3 MeV to 134 MeV which yielded (0.42±0.10)% as the relative branching ratio. The result, together with the $K_{e3\mathrm{}}$ branching ratio and the low-energy end of the $K_{\mu 3}$ muon energy spectrum, is found to satisfy a constant form factor $V-A$ interaction. The muon longitudinal polarization for the $K_{\mu 3}$ events was found to be +${0.8}_{-0.8\mathrm{}}^{+0.2\mathrm{}}$ which is two standard deviations from the calculated value -0.81 using the constant form factors which best fit the spectrum. A lifetime analysis of the decay modes gave $T\left(K_{\mu 3}\right)=(1.06\mathrm{}\pm 0.16)\times {18}^{-8\mathrm{}}$ sec, $T\left(K_{\pi 2}\right)=(1.197\mathrm{}\pm 0.032)\times {10}^{-8\mathrm{}}$ sec, and $T\left(K_{\mu 2}\right)=(1.259\mathrm{}\pm 0.018)\times {10}^{-8\mathrm{}}$ sec which are consistent with a single total lifetime, as expected. The total lifetime was found to be $T\left(K^{+}\right)=(1.231\mathrm{}\pm 0.011)\times {10}^{-8\mathrm{}}$ sec in agreement with previous values. The relative $\frac{K_{\mu 2}}{K_{\pi 2}}$ branching ratio was measured as 2.98±0.25. A search for the occurrence of an intermediate-mass lepton in the decay $K\to \chi +\nu$ established 3×${10}^{-4\mathrm{}}$ as the upper limit for the branching ratio with $m_e<m_{\chi }<75\mathrm{}$ MeV.