Mass Spectra of Charmed and Bottomed Mesons in 1/mQExpansion

Abstract

In these years, new excited states of charmed and bottomed mesons were discovered by some collaborations. D∗ 0(2308) and D′ 1(2427) observed by Belle1) are identified as cq (q = u/d) excited states with the quantum numbers JP = 0+ and 1+, respectively. Another set of heavy mesons, Ds0(2317) by BaBar2) and Ds1(2460) by CLEO3) are identified as cs excited states with the same quantum numbers as D. The decay widths of these excited DsJ mesons are narrow since the masses are below DK/D∗K threshold and hence the dominant decay modes violate the isospin invariance, whereas those excited D mesons are broad because of no such restriction as in DsJ cases. After the discovery of these states, two new Ds, Ds0(2860) and D∗ s(2715), were discovered in last year. Likewise some higher resonances of B/Bs particles were recently discovered. This situation opens a new era of spectroscopy of heavy-light mesons, which is challenging to theorists to solve these spectra. However, a conventional potential model fails to explain their masses and decay widths. Other approaches have been already proposed to understand these new states. Some people claim that these states may be candidates of new exotic state like a Tetra-quark. Those approaches are not yet completely established even though they may be interesting themselves. In this paper, we give a new formalism to calculate the mass spectra of heavy-light mesons including their radial excitation with respect to the relativistic effect, and explain these new states as a conventional Qq meson.8),9)