The puzzle of excessive non-DD¯ component of the inclusive ψ(3770) decay and the long-distant contribution

In this Letter we suggest that the obvious discrepancy between theoretical prediction on the non-DD¯ decays of ψ(3770) and data is to be alleviated by taking final state interaction (FSI) into account. By assuming that ψ(3770) overwhelmingly dissociates into DD¯, then the final state interaction induces a secondary process, we calculate the branching ratios of ψ(3770)→DD¯→J/ψη, ρπ, ωη, K∗K. Our results show that the branching ratio of ψ(3770)→non-DD¯ can reach up to Bnon-DD¯FSI=(0.2-1.1)% while typical parameters I=0.4GeV−2 and α=0.8-1.3 are adopted. This indicates that the FSI is obviously non-negligible.