
Physics 2005
Uniformly Accelerated Charge in a Quantum Field: From Radiation Reaction to Unruh EffectDOI: 10.1007/s1070100564041 Abstract: We present a stochastic theory for the nonequilibrium dynamics of charges moving in a quantum scalar field based on the worldline influence functional and the closetimepath (CTP or inin) coarsegrained effective action method. We summarize (1) the steps leading to a derivation of a modified AbrahamLorentzDirac equation whose solutions describe a causal semiclassical theory free of runaway solutions and without preacceleration patholigies, and (2) the transformation to a stochastic effective action which generates AbrahamLorentzDiracLangevin equations depicting the fluctuations of a particle's worldline around its semiclassical trajectory. We point out the misconceptions in trying to directly relate radiation reaction to vacuum fluctuations, and discuss how, in the framework that we have developed, an array of phenomena, from classical radiation and radiation reaction to the Unruh effect, are interrelated to each other as manifestations at the classical, stochastic and quantum levels. Using this method we give a derivation of the Unruh effect for the spacetime worldline coordinates of an accelerating charge. Our stochastic particlefield model, which was inspired by earlier work in cosmological backreaction, can be used as an analog to the black hole backreaction problem describing the stochastic dynamics of a black hole event horizon.
