X(3872) as a D-D* molecule bound by quark exchange forces

TL;DR

This paper models the X(3872) as a D-D* molecular bound state formed by quark exchange forces, solving the Bethe-Salpeter equation with a complex, energy-dependent potential derived from quark exchange processes.

Contribution

It introduces a novel approach using the Bethe-Salpeter equation with a meson-meson potential from quark exchange, explaining the binding of D and D* mesons in X(3872).

Findings

Bound state near 3.872 GeV in J/psi-rho continuum

Quark exchange forces can produce D-D* binding

Potential is complex and energy-dependent due to intermediate states

Abstract

The Bethe-Salpeter equation for the T-Matrix of D-D* scattering is solved with a meson-meson potential that results from 2nd order Born approximation of quark exchange processes. This potential turns out to be complex and energy dependent due to the pole contribution from the coupling to the intermediate J/psi-rho meson pair propagator. As a consequence, a bound state with a mass close to 3.872 GeV occurs in the J/psi-rho continuum. This result suggests that quark exchange forces may provide the solution to the puzzling question for the origin of the interaction which leads to a binding of D and D* mesons in the X(3872) state.