Recently LHCb collaboration discovered a doubly charmed tetraquark (Tcc) with exotic flavor content ccud slightly below DD* threshold. I’ll present the first lattice QCD determination of DD* scattering amplitude which is needed to theoretically establish Tcc. The resulting scattering amplitude provides a signature for a pole related to Tcc for the first time with ab-initio methods. 
https://indico.ijs.si/event/1424/