Asao Arai
Derivation of the Lamb Shift from an Effective Hamiltonian 
in Non-relativistic Quantum Electrodynamics
(226K, Latex 2e)

ABSTRACT.  Some aspects of spectral analysis of an effective Hamiltonian 
in non-relativistic quantum electrodynamics are reviewed. 
The Lamb shift of a hydrogen-like atom is derived as the lowest order approximation (in the fine structure 
constant) 
of an energy level shift of the effective Hamiltonian. Moreover, 
a general class of effective operators 
is presented, which comes from models of an abstract quantum system interacting with a Bose field.