Analysis of the exotic resonances in the systems $QQ\bar q\bar q$ and $Qq\bar Q\bar q$ with the extended recoupling model

Abstract

The phenomenon of a narrow peak X(3875), discovered recently by the LHCb in the $D^*D$ system, and the absence of resonances in the $D_sD_s$ and $D_s^*D_s^*$ systems is discussed within the new extended version of the Recoupling Model, where the resonance is the result of infinite recoupling transitions of confining strings between quarks and antiquarks. We show that existence of the resonance in the $D^*D$ and its absence in $D_sD_s$ and $D_s^*D_s^*$ systems are the natural results of the Recoupling Mechanism. The application of this mechanism to the $D\bar D^*$ system allows to obtain the resonance $Z_c(3900)$ with larger width in agreement with experimental data.