Factorization in the production and decay of the X(3872) -: art. no. 014012

The production and decay of the X(3872) are analyzed under the assumption that the X is a weakly bound molecule of the charm mesons D-0(D) over bar (*0) and D-*0(D) over bar (0). The decays imply that the large D-0(D) over bar (*0) scattering length has an imaginary part. An effective field theory for particles with a large complex scattering length is used to derive factorization formulas for production rates and decay rates of X. If a partial width is calculated in a model with a particular value of the binding energy, the factorization formula can be used to extrapolate to other values of the binding energy and to take into account the width of the X. The factorization formulas relate the rates for production of X to those for production of D-0(D) over bar (*0) and D-*0(D) over bar (0) near threshold. They also imply that the line shape of X differs significantly from that of a Breit-Wigner resonance.