Observation of the Decay $K_L\to {\mu }^{+}{\mu }^{-}\gamma \gamma$

Abstract

We have observed the decay $K_L\to {\mu }^{+}{\mu }^{-}\gamma \gamma$ at the KTeV experiment at Fermilab. This decay presents a formidable background to the search for new physics in $K_L\to {\pi }^0{\mu }^{+}{\mu }^{-}$. The 1997 data yielded a sample of 4 signal events, with an expected background of 0.155 $\pm$ 0.081 events. The branching ratio is $\mathcal{B}(K_L\to {\mu }^{+}{\mu }^{-}\gamma \gamma$) $=(10.4_{-5.9}^{+7.5}(\mathrm{stat})\pm 0.7(\mathrm{sys}))\times 10^{-9}$ with $m_{\gamma \gamma }\ge 1{MeV/c}^2$, consistent with a QED calculation which predicts $(9.1\pm 0.8)\times 10^{-9}$.

See also the paper "Search for the Decay $K_L\to {\pi }^0{\mu }^{+}{\mu }^{-}$", also by the KTeV collaboration

References in corpus (2)

• Search for the Decay $K_L\to {\pi }^0{\mu }^{+}{\mu }^{-}$
• Search for the Decay K_L -> pi^0 nu nubar using pi^0 -> e^+ e^- gamma

Cited by in corpus (3)

• Kaon Decays in the Standard Model
• Observation of the rare decay K_S -> pi^0mu^+mu^-
• New Physics Searches at Kaon and Hyperon Factories