The recoil correction and spin–orbit force for the possible B⁎B¯⁎ and D⁎D¯⁎ states

In the framework of the one-boson exchange model, we have calculated the effective potentials between two heavy mesons B⁎B¯⁎ and D⁎D¯⁎ from the t- and u-channel π-, η-, ρ-, ω- and σ  -meson exchanges. We keep the recoil corrections to the B⁎B¯⁎ and D⁎D¯⁎ systems up to O(1M2), which turns out to be important for the very loosely bound molecular states. Our numerical results show that the momentum-related corrections are favorable to the formation of the molecular states in the IG=1+IG=1+, JPC=1+−JPC=1+− in the B⁎B¯⁎ and D⁎D¯⁎ systems.