Resonances and convex co-compact congruence subgroups of PSL2(Z)
  This papers deals with congruence subgroups of convex cocompact subgroups of PSL2(Z). We examine the behaviour of the resonance spectrum when the congruence parameter q goes to infinity: we show a lower bound for the counting function in discs and an upper bound in vertical strips. These results show drastically different behaviour on both sides of the critical line $\Re(s)=\delta/2$. 
Fr\'ed\'eric Naud (LANLG), Dmitry Jakobson
math.SP math.NT