Speaker
Description
Accounting for loop radiative corrections, such as photon polarization and electron mass operators, become essential as the strength of the external field reaches the limit of ~1600 Sauter-Schwinger fields in the reference frame of a particle, namely, $\alpha\chi^{2/3}\sim 1$ where $\chi$ denotes the (dimensionless) field. It is sufficient to consider just 1-loop corrections below the limit $\alpha\chi^{2/3}< 1$. In the first part of this talk, we analyze the modification of the free electron propagation in a strong constant crossed field by the 1-loop mass correction.
At $\alpha\chi^{2/3}> 1$, any scattering problem requires a summation of loop radiative corrections to all orders. According to the Ritus-Narozhny conjecture, the leading order corrections are given by combining the 1-loop photon polarization operators with the bare photon lines, and (fortunately) appear to be summable. However, in effect, such dressed `photons' obtain a dynamical mass depending on $\chi$. Unless $\chi$ is small, they are violently unstable. This makes formulation of the photon emission probability quite intricate. We briefly review this issue and the possible ways to resolve it in the second part of the talk.
