V. Ziegler

Simple explanation for the X(3872) mass shift observed in the decay X(3872)-->D*0 D0.

We propose a simple explanation for the increase of approximately 3 MeV/c;{2} in the mass value of the X(3872) obtained from D(*0)D(0) decay relative to that obtained from decay to J/psipi(+)pi(-). If the total width of the X(3872) is 2-3 MeV, the peak position in the D(*0)D(0) invariant mass distribution is sensitive to the final state orbital angular momentum because of the proximity of the X(3872) to D(*0)D(0) threshold. We show that for total width 3 MeV and one unit of orbital angular momentum, a mass shift approximately 3 MeV/c(2) is obtained; experimental mass resolution should slightly increase this value. A consequence is that spin-parity 2(-) is favored for the X(3872).