Status of charmed meson spectroscopy

Abstract

The discovery of the ground state positive-parity charm-strange and charm-nonstrange mesons $ D_{s0}^* $(2317), D s 1 (2460), $ D_0^* $(2400) and D 1 (2430) in 2003 and 2004 brought up several mysteries related to their masses. Here I briefly review recent progresses from lattice calculations and analysis of the precise LHCb measurements of the B − → D + π − π − in the framework of unitarized chiral perturbation theory. It turns out that all the mysteries can be understood in a picture consistent with both lattice results and the LHCb measurements. In this picture, the main components of $ D_{s0}^* $(2317) and D s 1 (2460) are DK and D ∗ K hadronic molecules, respectively. Furthermore, the resonance parameters of the ground state 0 + and 1 + charm-nonstrange mesons take values very different from the known ones of the $ D_0^* $(2400) and D 1 (2430), which were obtained by using an improper resonance parameterization. It is pointed out that there should be two $ D_0^* $ and two D 1 broad states in region relevant to the $ D_0^* $ (2400) and D 1 (2430). Suggestions towards identifying the higher nonstrange resonances are given.