Heavy molecules and one-σ/ω-exchange model

In the framework of the one-boson-exchange model, we explore whether the intermediate- and short-range forces from sigma/omega exchange can be strong enough to bind heavy molecular states Lambda D-c((D) over bar) and Lambda(c)Lambda(c)((Lambda) over bar (c)) systems have been studied and compared. We find that the force from sigma exchange is attractive and dominant, whereas the omega-exchange force is not. As a consequence, the S-wave Lambda D-c, Lambda(c)Lambda(c), and Lambda(c)(Lambda) over bar (c) can be possible molecular candidates. We further indicate that a one hadron-hadron system with more light quarks (u, d) can be easier to form than a bound state. As a by-product, by studying the heavy-quark mass dependence for the Lambda D-c((D) over bar)-like and Lambda(c)Lambda(c)((Lambda) over bar (c))-like systems, we find that the charm/bottom sector can easily accommodate molecular states. Finally, the Lambda N-c((N) over bar) and Lambda N-b((N) over bar) systems are investigated. Our results indicate that they are also likely to form bound states. By including one-pi-exchange forces, providing additional attraction when coupled channels are included, we expect many molecular states in heavy-quark sectors.