This article presents the first measurement of the interaction between charm hadrons and nucleons. The
two-particle momentum correlations of pD− and p ̄Dþ pairs are measured by the ALICE Collaboration in pffiffi
high-multiplicity pp collisions at s 1⁄4 13 TeV. The data are compatible with the Coulomb-only
interaction hypothesis within ð1.1–1.5Þσ. The level of agreement slightly improves if an attractive nucleon
ðNÞD ̄ strong interaction is considered, in contrast to most model predictions which suggest an overall
repulsive interaction. This measurement allows for the first time an estimation of the 68% confidence level
interval for the isospin I 1⁄4 0 inverse scattering length of the ND ̄ state f−1 ∈ 1⁄2−0.4; 0.9 fm−1, assuming 0;I1⁄40
negligible interaction for the isospin I 1⁄4 1 channel.
