Photon correlation effects in charged-particle scattering in a radiation field

Abstract

The authors examine the role of finite bandwidth on the scattering line shape of charged particles, in the presence of a radiation field undergoing Gaussian amplitude and phase fluctuations. It is shown that in the strong particle-field interaction domain, the contribution to the scattering line width by the radiation field becomes significantly larger than the field bandwidth itself due to multiphoton higher order processes and could be comparable with that of the initial spread of the particle energy. In the weak interaction domain, with narrow-band lasers, as expected, the line width is controlled by the energy spread of the particle alone. The sharp line result obtained previously within the adiabatic approximation is exactly recovered in the appropriate limit. In the case of possible strong broad-band fields, the scattering line shape is expected to be dominated by the field fluctuations. Finally, numerical calculations are performed at selected parameter values to illustrate the results; among other things they indicate the existence of a known effective sum rule even in the presence of the random phase and amplitude fluctuations of the field.