X(3872) in lattice QCD with exact chiral symmetry

We investigate the mass spectrum of 1++ exotic mesons with quark content (cqc¯q¯), using molecular and diquark-antidiquark operators, in quenched lattice QCD with exact chiral symmetry. For the molecular operator {(q¯γic)(c¯γ5q)−(c¯γiq)(q¯γ5c)} and the diquark-antidiquark operator {(qTCγic)(q¯Cγ5c¯T)−(q¯CγiTc¯T)(qTCγ5c)}, both detect a resonance with mass around 3890±30MeV in the limit mq→mu, which is naturally identified with X(3872). Further, heavier exotic meson resonances with JPC=1++ are also detected, with quark content (csc¯s¯) around 4100±50MeV.