Unquenching the Quark Model in a Nonperturbative Scheme

الملخص EN

In recent years, the discovery in quarkonium spectrum of several states not predicted by the naive quark model has awakened a lot of interest.

A possible description of such states requires the enlargement of the quark model by introducing quark-antiquark pair creation or continuum coupling effects.

The unquenching of the quark models is a way to take these new components into account.

In the spirit of the Cornell Model, this is usually done by coupling perturbatively a quark-antiquark state with definite quantum numbers to the meson-meson channel with the closest threshold.

In this work we present a method to coupled quark-antiquark states with meson-meson channels, taking into account effectively the nonperturbative coupling to all quark-antiquark states with the same quantum numbers.

The method will be applied to the study of the X(3872) resonance and a comparison with the perturbative calculation will be performed.