Nature of the X(3872) from QCD

We have studied some possible four-quark and molecule configurations of the X(3872) using double ratios of sum rules, which are more accurate than the usual simple ratios often used in the literature to obtain hadron masses. We found that the different structures ((3) over bar - (3) over bar and (6) over bar - 6 tetraquarks and D - D(*) molecule) lead to the same prediction for the mass (within the accuracy of the method), indicating that the alone prediction of the X mass may not be sufficient to reveal its nature. In doing these analyses, we also find that (within our approximation) the use of the (MS) over bar running (m) over bar (c)(m(c)(2)), rather than the on-shell mass, is more appropriate to obtain the J/psi and X meson masses. Using vertex sum rules to roughly estimate the X(3872) hadronic and radiative widths, we found that the available experimental data does not exclude a lambda - J/psi-like molecule current.

Centre National de la Recherche Scientifique - CNRS-FAPESP

CNPq-Brazil

Centre National de la Recherche Scientifique - CNRS[IN2P3]