Below is the ascii version of the abstract for 99-29.
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V. Georgescu, M. Mantoiu
On the Spectral Theory of Dirac Type Hamiltonians
ABSTRACT. We introduce a class of matrix valued pseudo-differential operators that admit scalar
locally conjugate operators (in the sense of E. Mourre) and we give a general method
for studying singular perturbations of such operators.
In particular, we develop the spectral and scattering theory for a class of hamiltonians
which contains the Dirac operators with arbitrary Coulomb singularities.