Radiation reaction in ultra-relativistic laser-electron interactions

Seto, Keita*; Nagatomo, Hideo*; Koga, J. K.; Mima, Kunioki*

If the laser intensity is higher than W/cm, strong bremsstrahlung might occur with a relativistic motion. Accompanying this, the "radiation reaction force" works on the charged particle. Therefore, it is necessary to study the radiation reaction effects in the ultra relativistic laser-electron interaction regime. We've considered the Lorentz-Abraham-Dirac (LAD) equation which can describe this phenomena, but it has mathematical difficulties. For solving this, there are many methods (the approximation of the radiation reaction force, new assumptions of the model). The LAD equation has been recently derived by the effective Lagrangian method in QED. This comes from the diagram of self-photon interaction. We will discuss about the meaning of the LAD equation and some other equations.