Search for $K^0_{\mathrm{S(L)}}\to\mu^+\mu^-\mu^+\mu^-$ decays at LHCb

TL;DR

This paper reports a search for rare $K^0$ decays into four muons at LHCb, setting the first upper limits on their branching fractions with no evidence of signal found.

Contribution

First search for $K^0_{S,L} o 4\,\mu$ decays at LHCb, establishing upper limits on their branching fractions using 13 TeV data.

Findings

No evidence for the decays was observed.

Upper limits on branching fractions were set at $5.1\times 10^{-12}$ for $K_S^0$ and $2.3\times 10^{-9}$ for $K_L^0$.

These are the first limits for these decay modes.

Abstract

A search for $K_{\textrm{S(L)}}^0\rightarrow\mu^{+}\mu^{-}\mu^{+}\mu^{-}$ decays is performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1 $fb^{-1}$. No evidence for signal is found. The 90\% confidence level upper limits are the first set for both decays and are $B(K_{\textrm{S}}^0\rightarrow\mu^{+}\mu^{-}\mu^{+}\mu^{-}) < 5.1\times 10^{-12}$ and $B(K_{\textrm{L}}^0\rightarrow\mu^{+}\mu^{-}\mu^{+}\mu^{-}) < 2.3\times 10^{-9}$.