Searches for 25 rare and forbidden decays of D + and Ds+ mesons

Abstract

A search is performed for rare and forbidden charm decays of the form D + (s)→ h ±` +` (0)∓, where h ± is a pion or kaon and ` ( 0 )± is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1.6 fb−1 , collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1.4 × 10−8 and 6.4 × 10−6 . In most cases, these results represent an improvement on existing limits by one to two orders of magnitude.