Coupled channel approach to the structure of the X(3872)

We have performed a coupled channel calculation of the 1(++) c (c) over bar sector including q (q) over bar and DD* molecular configurations. The calculation was done within a constituent quark model which successfully describes the meson spectrum, in particular, the c (c) over bar 1(--) sector. Two and four-quark configurations are coupled using the P-3(0) model. The elusive X(3872) meson appears as a new state with a high probability for the DD* molecular component. When the mass difference between neutral and charged states is included, a large (DD)-D-0*(0) component is found which dominates for large distances and breaks isospin symmetry in the physical state. The original c (c) over bar (2(3)P(1)) state acquires a sizable DD* component and can be identified with the X(3940). We study the B -> K pi(+)pi(-)J/psi and B -> (KDD)-D-0*(0) decays, finding a good agreement with Belle and BABAR experimental data.