B Decays as Spectroscope for Charmed Four-quark States

Abstract

The $D_s(2320)$ state recently observed by BaBar in the $D_s^{+}{\pi }^0$ channel may be the first of a host of $cq\bar{q}\bar{q}$ four-quark states. We give a phenomenological account of the masses and decay modes. The isosinglet $D_s(2320)$ state is the only narrow one, dominated by the observed isospin violating decay and less than $\sim$ 100 keV in width. All other states are expected to decay hadronically. Notable resonances are in doubly charged $D_s^{+}{\pi }^{+}$, $D^{+}{K}^{+}$, wrong pairing $D^{+}{K}^{-}$, and also $D_s^{+}{K}^{-}$, $D\eta$ channels. We propose B decays as searching ground for such 4-quark states, which recoil against ${\bar{D}}^{(\ast )}$ meson from B decay, or ${\pi }^{+}$ ${\bar{D}}^{(\ast )}$, $\bar{K}$ mesons from $\bar{B}$ decay. Exotic $qc\bar{c}\bar{q}$ charmonia could also be produced, and may be behind the slow $J/\psi$ bump in inclusive $B\to J/\psi +X$ decay.

Comments: 6 pages and 2 figures