Many hadronic states observed since 2003, especially for the positive-parity charm-strange states $D_{s0}^ast (2317)$ and $D_{s1}(2460)$, do not conform with the conventional quark model expectations and raise various puzzles in charm meson spectroscopy. We demonstrate that those puzzles find a natural solution thanks to the recent development of chiral effective theory and Lattice simulations. The existence of the $D_{s0}^ast (2317)$ and $D_{s1}(2460)$ are attributed to the nonperturbative dynamics of Goldstone bosons scattering off $D$ and $D^ast$ mesons. It indicates that the lowest positive parity nonstrange scalar charm mesons, the $D_0^ast(2400)$ in the Review of Particel Physics, should be replaced by two states. The well constructed amplitudes are fully in line with the high quality data on the decays $B^-to D^+pi^-pi^-$ and $D_s^0to bar{D}^0K^-pi^+$. This implies that the lowest positve-parity states are dynamically generated rather than conventional quark-antiquark states. This pattern has also been established for the scalar and axial-vector mesons made from light quarks ($u$, $d$ and $s$ quarks).
Download