Pi-Pi Scattering with Nf=2+1+1 Twisted Mass Fermions

Pi-Pi scattering is investigated for the first time for Nf=2+1+1 dynamical quark flavours using Wilson twisted mass fermions. L"uscher’s finite size method is used to relate energy shifts in finite volume to scattering quantities like the scattering length in the I=2 channel. The computation is performed at several pion masses and lattice spacings utilising the stochastic LapH method.