After taking into account both the pion and sigma meson exchange potential, we have performed a dynamical calculation of the D 0 D * 0 system. The σ meson exchange potential is repulsive from heavy quark symmetry and numerically important for a loosely bound system. Our analysis disfavors the interpretation of X(3872) as a loosely bound molecular state if we use the experimental D * Dπ coupling constant g = 0.59 and a reasonable cutoff around 1 GeV, which is the typical hadronic scale. Bound state solutions with negative eigenvalues for the D D * system exist only with either a very large coupling constant (two times of the experimental value) or a large cutoff (Λ ∼ 6 GeV or β ∼ 6 GeV 2 ). In contrast, there probably exists a loosely bound S-wave B B * molecular state. Once produced, such a molecular state would be rather stable since its dominant decay mode is the radiative decay through B * → Bγ. Experimental search of these states will be very interesting.

There has been important experimental progress in the sector of heavy baryons in the past several years. We study the strong decays of the S-wave, P-wave, D-wave and radially excited charmed baryons using the $^3P_0$ model. After comparing the calculated decay pattern and total width with the available data, we discuss the possible internal structure and quantum numbers of those charmed baryons observed recently.Comment: 13 pages, 9 figures, 9 tables. Some descriptions changed. Published version in PR

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