Classical and quantum radiation reaction in conformally flat spacetime

Understand

We investigate the physics of a charged scalar particle moving in conformally flat spacetime with the conformal factor depending only on time in the framework of quantum electrodynamics (QED).

• In particular, we show that the radiation-reaction force derived from QED agrees with the classical counterpart in the limit $\hbar \to 0$ using the fact that to lowest order in $\hbar$ the charged scalar field theory with mass $m$ in conformally flat spacetime with conformal factor $\Omega(t)$, which we call Model B, is equivalent to that in flat spacetime with a time-dependent mass $m\Omega(t)$, which we call Model A, at tree level in this limit.
• We also consider the one-loop QED corrections to these two models in the semi-classical approximation.
• We find nonzero one-loop corrections to the mass and Maxwell's equations in Model A at order $\hbar^{-1}$.