arXiv subjects
Publications and source records attributed to Massimo Bertini.
We show that the Segal quantization of an arbitrary system of decoupled harmonic oscillators is unique in the sense that the one particle Hilbert space is completely determined by the requests of being a naturally complex symplectic space carrying a unitary realization of the dynamical evolution of the considered system.
The present paper is devoted to the detailed study of quantization and evolution of the point limit of the Pauli-Fierz model for a charged oscillator interacting with the electromagnetic field in dipole approximation. In particular, a well defined dynamics is constructed for the classical model, which is subsequently quantized according to the Segal scheme. To this end, the classical model in the point limit is reformulated as a second order abstract wave equation, and a consistent quantum evolution is given. This allows a study of the behaviour of the survival and transition amplitudes for the process of decay of the excited states of the charged particle, and the emission of photons in the decay process. In particular, for the survival amplitude the exact time behaviour is found. This is completely determined by the resonances of the systems plus a tail term prevailing in the asymptotic, long time regime. Moreover, the survival amplitude exhibites in a fairly clear way the Lamb shift correction to the unperturbed frequencies of the oscillator.
Given the abstract wave equation $\ddotϕ-Δ_αϕ=0$, where $Δ_α$ is the Laplace operator with a point interaction of strength $α$, we define and study $\bar W_α$, the associated wave generator in the phase space of finite energy states. We prove the existence of the phase flow generated by $\bar W_α$, and describe its most relevant properties with particular emphasis on the associated symplectic structure and scattering theory