First study of the two-body scattering involving charm hadrons

Abstract

This article presents the first measurement of the interaction between charm hadrons and nucleons. The two-particle momentum correlations of p D − and ¯ p D + pairs are measured by the ALICE Collaboration inhigh-multiplicity pp collisions at √ s = 13 TeV . Thedata are compatible with theCoulomb-only interaction hypothesis within ( 1.1– 1.5 ) σ . The level of agreement slightlyimproves if an attractive nucleon ( N ) ¯ D strong interaction is considered,incontrast to most model predictions which suggest an overall repulsive interaction. This measurement allows for the first time an estimation ofthe68% confidence levelinterval for theisospin I = 0inverse scattering lengthof the N ¯ D state f − 1 0, I = 0 ∈ [ − 0.4 , 0.9 ] fm − 1 , assuming negligible interaction for the isospin I = 1 channel.