We study near-threshold DDˉ scattering in S and D-wave to determine whether or not resonances or bound states are present. Working in the approximation where charm-annihilation is forbidden, with two degenerate light-quark flavors and a heavier strange quark, isospin is a good quantum number, and the only other other channel that is kinematically open is ηcη. Using lattice QCD we compute, as a function of varying light-quark mass, the S-matrix for coupled-channel ηcη−DDˉ scattering and find only weakly interacting meson pairs. In contrast to several other studies, we find no evidence for any bound-state or resonance singularity in the energy region between the deeply-bound χc0(1P) state and the DsDˉs threshold.
@article{arxiv.2602.09862,
title = {$D\bar{D}$ interactions are weak near threshold in QCD},
author = {David J. Wilson and Jozef J. Dudek and Robert G. Edwards and Christopher E. Thomas},
journal= {arXiv preprint arXiv:2602.09862},
year = {2026}
}