A priori estimates for the Helmholtz equation with electromagnetic   potentials in exterior domains
  We study the Helmholtz equation with electromagnetic-type perturbations, in the exterior of a domain, in dimension $n\geq3$. We prove, by multiplier techniques in the sense of Morawetz, a family of a priori estimates from which the limiting absorption principle follows. Moreover, we give some standard applications to the absence of embedded eigenvalues and zero-resonances, under explicit conditions on the potentials. 
Juan Antonio Barcel\'o, Luca Fanelli, Alberto Ruiz, Maricruz Vilela
math.AP math-ph math.MP