On the Gauge Invariance of the Transition Probability of a Charged Particle in Electromagnetic Field

Abstract

This paper suggests a principle to find a unitary operator U which transforms non-physical quantity, zero-potential Hamiltonian H0, into true physical quantity UH0U† for a charged particle in classical electromagnetic field, and puts forward a unified form of constructing gauge-independent transition probabilities in this case. Different methods correspond to different unitary operators which satisfy the above-mentioned principle.