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arXiv · hep-ex/9910047

A New Measurement of the Rare Decay $K^+\to π^+ μ^+ μ^-$

H. Ma·R. Appel·G. S. Atoyan·B. Bassalleck·D. Bergman·N. Cheung·S. Dhawan·H. Do·J. Egger·S. Eilerts·H. Fischer·W. Herold·V. V. Issakov·H. Kaspar·D. E. Kraus·D. M. Lazarus·P. Lichard·J. Lowe·J. Lozano·W. Majid·W. Menzel·S. Pislak·A. A. Poblaguev·P. Rehak·A. Sher·J. A. Thompson·P. Truoel·M. E. Zeller
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Abstract

More than 400 $K^{+}\toπ^{+}μ^+μ^-$ events were observed in a rare $K^+$ decay experiment at the AGS. Normalized to the $K^{+}\toπ^{+}π^+π^-$ decay, the branching ratio is determined to be $(9.22 \pm 0.60 (stat) \pm 0.49 (syst))\times 10^{-8}$. This branching ratio and the $μμ$ mass spectrum is in very good agreement with the measurement of the $K^{+}\toπ^{+}e^+e^-$ decay, but deviates significantly from the previous measurement.

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H. Ma, R. Appel, G. S. Atoyan, B. Bassalleck, D. Bergman, N. Cheung, S. Dhawan, H. Do, J. Egger, S. Eilerts, H. Fischer, W. Herold, V. V. Issakov, H. Kaspar, D. E. Kraus, D. M. Lazarus, P. Lichard, J. Lowe, J. Lozano, W. Majid, W. Menzel, S. Pislak, A. A. Poblaguev, P. Rehak, A. Sher, J. A. Thompson, P. Truoel, M. E. Zeller. 1999-10-21. A New Measurement of the Rare Decay $K^+\to π^+ μ^+ μ^-$. https://doi.org/10.1103/physrevlett.84.2580

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