Searches for 25 rare and forbidden decays of D+ and D s + $$ {D}_s^{+} $$ mesons

Abstract

Abstract

A search is performed for rare and forbidden charm decays of the form

D

s

+

→

h ±

ℓ +

ℓ

′

∓

$$ {D}_{(s)}^{+}\to {h}^{\pm }{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{\left(\prime \right)\mp } $$ , where h± is a pion or kaon and ℓ(′)± 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.