Analysis of J/psi pi+ pi- and D0 D0-bar pi0 Decays of the X(3872)

We analyze recent data from the Babar and Belle Collaborations on the X(3872) resonance in the J/psi pi+ pi- and D0 D0-bar pi0 decay channels, taking careful account of the universal features of an S-wave threshold resonance. Because the line shapes for such a resonance are not integrable functions of the energy, the resonance parameters depend on the prescriptions used to define them. In recent experimental analyses of the D0 D0-bar pi0 channel, an event near the D*0 D0-bar threshold was assumed to come from D*0 D0-bar or D0 D0*-bar and was therefore assigned an energy above the threshold. Taking this effect into account, our analysis of the D0 D0-bar pi0 data gives a mass for the X(3872) that is below the D*0 D^0-bar threshold. Our analyses in both the J/psi pi+ pi- and D0 D0-bar pi0 channels are consistent with the identification of the X(3872) as an extremely weakly-bound charm meson molecule.