Equivalence of resolvent and scattering resonances on quantum graphs
  We discuss resonances for Schr\"odinger operators on metric graphs which consists of a finite compact part and a finite number of halflines attached to it; the vertex coupling is assumed to be of the $\delta$-type or certain modifications of it. Using exterior complex scaling on the graph we show that the resolvent and scattering resonances coincide in this case. 
Pavel Exner and Ji\v{r}\'i Lipovsk\'y