Eur. Phys. J. C (2017) 77: 94
https://doi.org/10.1140/epjc/s10052-017-4660-9

Regular Article - Theoretical Physics

– interactions in finite volume and X(5568)

¹ School of Physics and Nuclear Energy Engineering, International Research Center for Nuclei and Particles in the Cosmos, Beijing Key Laboratory of Advanced Nuclear Materials and Physics, Beihang University, Beijing, 100191, China
² State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, 100871, China

^* e-mail: lisheng.geng@buaa.edu.cn

Received: 6 October 2016
Accepted: 30 January 2017
Published online: 13 February 2017

Abstract

The recent observation of X(5568) by the D0 Collaboration has aroused a lot of interest both theoretically and experimentally. In the present work, we first point out that X(5568) and cannot simultaneously be of molecular nature, from the perspective of heavy-quark symmetry and chiral symmetry, based on a previous study of the lattice QCD scattering lengths of DK and its coupled channels. Then we compute the discrete energy levels of the and system in finite volume using unitary chiral perturbation theory. The comparison with the latest lattice QCD simulation, which disfavors the existence of X(5568), supports our picture where the and interactions are weak and X(5568) cannot be a and molecular state. In addition, we show that the extended Weinberg compositeness condition also indicates that X(5568) cannot be a molecular state made from and interactions.