# Improved limit on the branching fraction of the rare decay ${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$

Abstract : A search for the decay ${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$ is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of $3\,\text{ fb }^{-1}$ , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 $\mathrm {\,TeV}$ . The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of $\mathcal{B}({{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-) < 0.8~(1.0) \times 10^{-9}$ at $90\%~(95\%)$ confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.
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Journal articles

https://hal.archives-ouvertes.fr/hal-01645701
Contributor : Inspire Hep <>
Submitted on : Thursday, November 23, 2017 - 10:36:34 AM
Last modification on : Wednesday, October 16, 2019 - 8:41:07 PM

### Citation

Roel Aaij, Bernardo Adeva, Marco Adinolfi, Ziad Ajaltouni, Simon Akar, et al.. Improved limit on the branching fraction of the rare decay ${{K} ^0_{\mathrm { \scriptscriptstyle S}}} \rightarrow \mu ^+\mu ^-$. Eur.Phys.J.C, 2017, 77 (10), pp.678. ⟨10.1140/epjc/s10052-017-5230-x⟩. ⟨hal-01645701⟩

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