Leptogenesis scenarios for natural SUSY with mixed axion-higgsino dark
  matter
  Supersymmetric models with radiatively-driven electroweak naturalness require
light higgsinos of mass ~ 100-300 GeV. Naturalness in the QCD sector is invoked
via the Peccei-Quinn (PQ) axion leading to mixed axion-higgsino dark matter.
The SUSY DFSZ axion model provides a solution to the SUSY mu problem and the
Little Hierarchy \mu << m_{3/2} may emerge as a consequence of a mismatch
between PQ and hidden sector mass scales. The traditional gravitino problem is
now augmented by the axino and saxion problems, since these latter particles
can also contribute to overproduction of WIMPs or dark radiation, or violation
of BBN constraints. We compute regions of the T_R vs. m_{3/2} plane allowed by
BBN, dark matter and dark radiation constraints for various PQ scale choices
f_a. These regions are compared to the values needed for thermal leptogenesis,
non-thermal leptogenesis, oscillating sneutrino leptogenesis and Affleck-Dine
leptogenesis. The latter three are allowed in wide regions of parameter space
for PQ scale f_a~ 10^{10}-10^{12} GeV which is also favored by naturalness:
f_a~ \sqrt{\mu M_P/\lambda_\mu }\sim 10^{10}-10^{12} GeV. These f_a values
correspond to axion masses somewhat above the projected ADMX search regions.
