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SUMMARY:Causality\, sum rules\, and scattering bounds - Gerhard Kristensso
 n (Lund University)
DTSTART:20230324T093000Z
DTEND:20230324T100000Z
UID:TALK195613@talks.cam.ac.uk
DESCRIPTION:Many physical systems satisfy causality\, i.e.\, the effect ca
 nnot precede its cause. In this presentation\, we explore some of the cons
 equences of this concept. We use a class of analytic functions that maps t
 he upper complex half plane onto itself. These functions are called Herglo
 tz functions\, and they are instrumental in our treatment. We employ a set
  of integral identities\, which gives a collection of sum rules. These sum
  rules can be applied to scattering and transmission problems and give phy
 sical bounds on the system. We exemplify with a series of examples from el
 ectromagnetic problems. The acoustic problem is briefly discussed as well 
 as some possible extensions.
LOCATION:Seminar Room 1\, Newton Institute
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