Search for rare and forbidden decays of charm and charmed-strange mesons to final states h{sup {+-}}e{sup {-+}}e{sup +}

We have searched for flavor-changing neutral current decays and lepton-number-violating decays of D{sup +} and D{sub s}{sup +} mesons to final states of the form h{sup {+-}}e{sup {-+}}e{sup +}, where h is either {pi} or K. We use the complete samples of CLEO-c open-charm data, corresponding to integrated luminosities of 818 pb{sup -1} at the center-of-mass energy E{sub CM}=3.774 GeV containing 2.4x10{sup 6} D{sup +}D{sup -} pairs and 602 pb{sup -1} at E{sub CM}=4.170 GeV containing 0.6x10{sup 6} D{sub s}{sup *{+-}}D{sub s}{sup {-+}} pairs. No signal is observed in any channel, and we obtain 90% confidence level upper limits on branching fractions B(D{sup +}{yields}{pi}{sup +}e{sup +}e{sup -})<5.9x10{sup -6}, B(D{sup +}{yields}{pi}{sup -}e{sup +}e{sup +})<1.1x10{sup -6}, B(D{sup +}{yields}K{sup +}e{sup +}e{sup -})<3.0x10{sup -6}, B(D{sup +}{yields}K{sup -}e{sup +}e{sup +})<3.5x10{sup -6}, B(D{sub s}{sup +}{yields}{pi}{sup +}e{sup +}e{sup -})<2.2x10{sup -5}, B(D{sub s}{sup +}{yields}{pi}{sup -}e{sup +}e{sup +})<1.8x10{sup -5}, B(D{sub s}{sup +}{yields}K{sup +}e{sup +}e{sup -})<5.2x10{sup -5}, and B(D{sub s}{sup +}{yields}K{sup -}e{sup +}e{sup +})<1.7x10{sup -5}.