Hadronic molecular states composed of heavy flavor baryons

We investigate the possible molecules composed of two heavy flavor baryons such as A(Q)B(Q)'' (Q = b, c) within the one-pion-exchange model (OPE). Our results indicate that the long-range pi exchange force is strong enough to form molecules such as [Sigma(Q)Xi(Q)'](S=1)(I=1/2) (Q = b, c), [Sigma(Q)Lambda(Q)](S=1)(I=1) (Q = b, c), [Sigma(b)Xi(b)'](S=1)(I=3/2), and [Xi(b)Xi(b)'](S=1)(I=0) where the S-D mixing plays an important role. In contrast, the pi exchange does not form the spin-singlet A(Q)B(Q) bound states. If we consider the heavier scalar and vector meson exchanges as well as the pion exchange, some loosely bound spin-singlet S-wave states appear while results of the spin-triplet A(Q)B(Q) system do not change significantly, which implies the pion exchange plays an dominant role in forming the spin-triplet molecules. Moreover, we perform an extensive coupled channel analysis of the Lambda(Q)Lambda(Q) system within the OPE and one-boson-exchange framework and find that there exist loosely bound states of Lambda(Q)Lambda(Q) (Q = b, c) with quantum numbers I(J(P)) = 0(0(+)), 0(0(-)), and 0(1(-)). The binding solutions of Lambda(Q)Lambda(Q) system mainly come from the coupled-channel effect in the flavor space. Besides the OPE force, the medium-and short-range attractive force also plays a significant role in the formation of the loosely bound Lambda(c)Lambda(c) and Lambda(b)Lambda(b) states. Once produced, they will be very stable because such a system decays via weak interaction with a very long lifetime around 10(-13)-10(-12) s.