Exotic Qqq¯q¯ states in the chiral quark model

Abstract

In the framework of the chiral quark model, we investigate the Qqq¯q¯ (Q=c, b and q=u, d) tetraquark system with two structures: Qq¯−qq¯ and Qq−q¯q¯. The bound-state calculation shows that for the single channel, there is no evidence for any bound state below the minimum threshold in both cqq¯q¯ and bqq¯q¯ systems. However, after coupling all channels of two structures, we obtain a bound state below the minimum threshold in the cqq¯q¯ system with the energy of 1998 MeV, and the quantum number is IJP=120+. Meanwhile, in the bqq¯q¯ system, two bound states with energies of 5414 MeV and 5456 MeV are obtained, and the quantum numbers are IJP=120+ and IJP=121+, respectively. Besides, we also employ the real-scaling method to search for resonance states in the cqq¯q¯ and bqq¯q¯ systems. Unfortunately, no genuine resonance states were obtained in both systems. We suggest future experiments to search for these three possible bound states. Published by the American Physical Society 2024