Improved limit on the branching fraction of the rare decay K S 0 μ + μ -

Eur Phys J C Part Fields. 2017;77(10):678. doi: 10.1140/epjc/s10052-017-5230-x. Epub 2017 Oct 13.

Abstract

A search for the decay K S 0 μ + μ - is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of 3 fb - 1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV . The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of B ( K S 0 μ + μ - ) < 0.8 ( 1.0 ) × 10 - 9 at 90 % ( 95 % ) confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude.