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In this paper, we present a data-driven analysis of the $\gamma\gamma\toD^+D^-$ and $\gamma\gamma\to D^0\bar{D}^0$ reactions from threshold up to 4.0GeV in the $D\bar{D}$ invariant mass. For the $S$-wave contribution, we adopt apartial-wave dispersive representation, which is solved using the $N/D$ ansatz.The left-hand cuts are accounted for using the model-independent conformalexpansion. The $D$-wave $\chi_{c2}(3930)$ state is described as a Breit-Wignerresonance. The resulting fits are consistent with the data on the invariantmass distribution of the $e^+e^- \to J/\psi D\bar{D}$ process. Performing ananalytic continuation to the complex $s$-plane, we find no evidence of a polecorresponding to the broad resonance $X(3860)$ reported by the BelleCollaboration. Instead, we find a clear bound state below the $D\bar{D}$threshold at $\sqrt{s_B} = 3695(4)$ MeV, confirming the previousphenomenological and lattice predictions.

Dispersive analysis of the $\gamma\gamma \to D \bar{D}$ data and the confirmation of the $D \bar{D}$ bound state