Preprint A98/2001
On Huygens' Principle for Dirac Operators Associated to Electromagnetic Fields

Fabio Chalub

**Keywords: **
Huygens' Principle | Dirac Operators | Electromagnetic Fields | Hadamard's Problem

We study the behavior of massless Dirac particles, i.e., solutions
of the Dirac equation with $m=0$ in the presence of an electromagnetic
field. Our main result (Theorem~\ref{eletromag})
is that for purely real or imaginary fields
any Huygens type (in Hadamard's sense) Dirac operators
is equivalent to the free Dirac operator, equivalence given
by changes of variables and multiplication (right and left)
by nonzero functions.