Evidence for X(3872) from DD* Scattering on the Lattice

A candidate for the charmonium(like) state X(3872) is found 11±7MeV below the DD¯^* threshold using dynamical N_f=2 lattice simulation with J^PC=1⁺⁺ and I=0. This is the first lattice simulation that establishes a candidate for X(3872) in addition to the nearby scattering states DD¯^* and J/ψω, which inevitably have to be present in dynamical QCD. We extract large and negative DD¯^* scattering length a₀^DD*=-1.7±0.4fm and the effective range r₀^DD*=0.5±0.1fm, but their reliable determination will have to wait for a simulation on a larger volume. In I=1 channel, only the DD¯^* and J/ψρ scattering states are found and no candidate for X(3872). This is in agreement with the interpretation that X(3872) is dominantly I=0, while its small I=1 component arises solely from the isospin breaking and is therefore absent in our simulation with m_u=m_d.