Mixed axion/neutralino dark matter in the SUSY DFSZ axion model
  We examine mixed axion/neutralino cold dark matter production in the SUSY
DFSZ axion model where an axion superfield couples to Higgs superfields. We
calculate a wide array of axino and saxion decay modes along with their decay
temperatures, and thermal and non-thermal production rates. For a SUSY
benchmark model with a standard underabundance (SUA) of Higgsino-like dark
matter (DM), we find for the PQ scale f_a< 10^{12} GeV that the DM abundance is
mainly comprised of axions as the saxion/axino decay occurs before the standard
neutralino freeze-out and thus its abundance remains suppressed. For 10^{12}<~
f_a<~ 10^{14} GeV, the saxion/axino decays occur after neutralino freeze-out so
that the neutralino abundance is enhanced by the production via decay and
subsequent re-annihilation. For f_a>~ 10^{14} GeV, both neutralino dark matter
and dark radiation are typically overproduced. For judicious parameter choices,
these can be suppressed and the combined neutralino/axion abundance brought
into accord with measured values. A SUSY benchmark model with a standard
overabundance (SOA) of bino DM is also examined and typically remains excluded
due at least to too great a neutralino DM abundance for f_a<~ 10^{15} GeV. For
f_a>~ 10^{15} GeV and lower saxion masses, large entropy production from saxion
decay can dilute all relics and the SOA model can be allowed by all
constraints.
