Experimental evidence for an attractive p-$\phi$ interaction

TL;DR

This paper provides the first experimental evidence of an attractive strong interaction between protons and phi mesons, using high-energy collision data to extract scattering parameters and analyze the nature of their interaction.

Contribution

It presents the first experimental measurement of the p-$$ interaction, including scattering length and effective range, and analyzes the interaction with phenomenological potentials.

Findings

The p-$$ interaction is attractive and dominated by elastic scattering.

The imaginary part of the scattering length is consistent with zero.

The N-$$ coupling constant is estimated to be 0.14  0.03 (stat.)  0.02 (syst.).

Abstract

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-$\phi \oplus \overline{\rm {p}}$-$\phi$ pairs measured in high-multiplicity pp collisions at $\sqrt{s}~=~13$ 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 Lednick\'y-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 $g_{\rm{N}-\phi} = 0.14\pm 0.03\,(\mathrm{stat.})\pm 0.02\,(\mathrm{syst.})$. 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.