Experimental Evidence for an Attractive Interaction p-phi interaction

This Letter presents the first experimental evidence of the attractive strong interaction between a proton and a phi meson. The result is obtained from two-particle correlations of combined p-phi circle plus (p) over bar-phi pairs measured in high-multiplicity pp collisions at root s = 13 TeV by the ALICE Collaboration. The spin-averaged scattering length and effective range of the p-phi interaction are extracted from the fully corrected correlation function employing the Lednicky-Lyuboshits approach. In particular, the imaginary part of the scattering length vanishes within uncertainties, indicating that inelastic processes do not play a prominent role for the p-phi interaction. These data demonstrate that the interaction is dominated by elastic p-phi scattering. Furthermore, an analysis employing phenomenological Gaussian-and Yukawa-type potentials is conducted. Under the assumption of the latter, the N-phi coupling constant is found to be g(N-phi) = 0.14 +/- 0.03(stat) +/- 0.02(syst). This work provides valuable experimental input to accomplish a self-consistent description of the N-phi interaction, which is particularly relevant for the more fundamental studies on partial restoration of chiral symmetry in nuclear medium.