R. Faccini, F. Piccinini, A. Pilloni, A. D. Polosa
Whether the much studied X(3872) is an axial or tensor resonance makes an important difference for its interpretation. A recent paper by the BaBar collaboration raised the viable hypothesis that it might be a 2-+ state based on the 3 pions spectrum in the X -> J/psi omega decays. Starting from a general parametrization of the decay amplitudes for the axial and tensor quantum numbers of the X, we analyze two models that differ by the functional form used to define the decay momentum dependence of the strong couplings. The level of agreement of the two models with data is interpreted with a statistical approach based on Monte Carlo simulations, to be robust against the dilution induced by the scarce sensitivity of the X -> J/psi rho channel to the spin of the X. Such analysis returns a probability of 0.2% (0.7%) and 46% (11%) for the 1++ and 2-+ hypotheses respectively, for the two models used. Either way the preference for the 2-+ assignment is enhanced with respect to the original BaBar analysis calling for new data in the 3 pions spectrum.
View original:
http://arxiv.org/abs/1204.1223
No comments:
Post a Comment