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Lower bounds for resonance counting functions for obstacle scattering in even dimensions
- American Journal of Mathematics
- Johns Hopkins University Press
- Volume 139, Number 3, June 2017
- pp. 617-640
- 10.1353/ajm.2017.0016
- Article
- Additional Information
In even dimensional Euclidean scattering, the resonances lie on the logarithmic cover of the complex plane. This paper studies resonances for obstacle scattering in ${\Bbb R}^d$ with Dirichlet, Neumann, or admissible Robin boundary conditions, when $d$ is even. Set $n_m(r)$ to be the number of resonances with norm at most $r$ and argument between $m\pi$ and $(m+1)\pi$. Then $\lim\sup_{r\rightarrow\infty}{\log n_m(r)\over\log r}=d$ if $m\in{\Bbb Z}\setminus\{0\}$.