Cuts, Cancellations and the Closed Time Path: The Soft Leptogenesis
  Example
  By including all leading quantum-statistical effects at finite temperature,
we show that no net asymmetry of leptons and sleptons is generated from soft
leptogenesis, save the possible contribution from the resonant mixing of
sneutrinos. This result contrasts with different conclusions appearing in the
literature that are based on an incomplete inclusion of quantum statistics. We
discuss vertex and wave-function diagrams as well as all different possible
kinematic cuts that nominally lead to CP-violating asymmetries. The present
example of soft leptogenesis may therefore serve as a paradigm in order to
identify more generally applicable caveats relevant to alternative scenarios
for baryogenesis and leptogenesis, and it may provide useful guidance in
constructing viable models.
