Dark matter asymmetry in supersymmetric Dirac leptogenesis
  We discuss asymmetric or symmetric dark matter candidate in the
supersymmetric Dirac leptogenesis scenario. By introducing a singlet superfield
coupling to right-handed neutrinos, the overabundance problem of dark matter
can be evaded and various possibilities for dark matter candidate arise. If the
singlino is the lightest supersymmetric particle (LSP), it becomes naturally
asymmetric dark matter. On the other hand, the right-handed sneutrino is a
symmetric dark matter candidate whose relic density can be determined by the
usual thermal freeze-out process. The conventional neutralino or gravitino LSP
can be also a dark matter candidate as its non-thermal production from the
right-handed sneutrino can be controlled appropriately. In our scenario, the
late-decay of heavy supersymmetric particles mainly produce the right-handed
sneutrino and neutrino which is harmless to the standard prediction of the
big-bang nucleosynthesis.
