We study DDˉ∗ (D∗Dˉ) scattering in the framework of unitarized heavy meson chiral perturbation theory with pion exchange and a contact interaction. 3S1−3D1 mixing effects are taken into account. A loosely bound state X(3872), with the pole position being Mpole=(3871.70−i0.39)MeV, is found. The result is not sensitive to the strength of the contact interaction. Our calculation provides a theoretical confirmation of the existence of the 1++ state X(3872). The light quark mass dependence of the pole position indicates it has a predominately DDˉ∗ (D∗Dˉ) molecular nature. When the π mass is larger than 142 MeV, the pole disappears which makes impossible the lattice simulation of this state at large quark mass.
@article{arxiv.1304.0846,
title = {Study on X(3872) from effective field theory with pion exchange interaction},
author = {P. Wang and X. G. Wang},
journal= {arXiv preprint arXiv:1304.0846},
year = {2013}
}