Charged-to-neutral meson yield ratio at $\psi (3770)$ and ${\rm Y}(4S)$ revisited

Abstract

The recent precision measurement of the relative yield of $D^{+}{D}^{-}$ and $D^0{\bar{D}}^0$ meson pairs at the $\psi (3770)$ peak in $e^{+}{e}^{-}$ annihilation is about 3.7 sigma away from a straightforward theoretical estimate. It is argued that combined with an even more significant deviation of similar ratio for the $B$ mesons at the ${\rm Y}(4S)$ peak, this provides an insight into the structure of heavy mesons and requires both a form factor, corresponding to their finite `size', and a strong interaction between the mesons mesons in the isovector state $I^G(J^P)=1^{+}(1^{-})$. It is also argued that the data for the $D$ and $B$ mesons are possibly compatible with the heavy quark limit of the same meson-antimeson strong interaction in both systems.

Comments: 8 pages, 2 figures