Basis invariant description of chemical equilibrium with implications for a recent axionic leptogenesis model

Understand

We provide a systematic treatment of chemical equilibrium in the presence of a specific type of time dependent background.

• The type of time dependent background we consider appears, for example, in recently proposed axion/Majoron leptogenesis models [1,2].
• In describing the chemical equilibrium we use quantities which are invariant under redefinition of fermion phases (we refer to this redefinition as a change of basis for short), and therefore it is a basis invariant treatment.
• The change of the anomaly terms due to the change of the path integral measure [3,4] under a basis change is taken into account.