## Evidence for the rare decay $\Sigma^+ \to p \mu^+ \mu^-$

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Original language English Aaij:2017ddf 221803 Physical Review Letters 120 22 https://doi.org/10.1103/PhysRevLett.120.221803 Published - 1 Jun 2018

### Abstract

A search for the rare decay Σ+→pμ+μ- is performed using pp collision data recorded by the LHCb experiment at center-of-mass energies s=7 and 8 TeV, corresponding to an integrated luminosity of 3  fb-1. An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured Σ+→pμ+μ- branching fraction is (2.2-1.3+1.8)×10-8, where statistical and systematic uncertainties are included, which is consistent with the standard model prediction.

ID: 90517217