Event № 121
First-order systems of partial differential equations appear in many areas of physics, from the Maxwell equations to the Dirac operator. The aim of the talk is to describe a general method for the study ofthe spectral density of all such systems, connecting it to traces on the (geometric-optical) "slowness surfaces" . The Holder continuity of the spectral density leads to a derivationof the limiting absorption principle and global spacetime estimates. (based on joint work with Tomio Umeda).