Experimental evidence for an attractive p-$φ$ 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-$\phi \oplus \overline{\rm {p}}$-$\phi$ 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.

 

PRL 127 (2021) 172301
HEP Data
e-Print: arXiv:2105.05578 | PDF | inSPIRE
CERN-EP-2021-081
Figure group

Figure 1

The experimental \pphi correlation function $C_{\mathrm{exp}}(\kstar)$ and various contributions as described in Eq. ???. Statistical (bars) and systematic uncertainties (boxes) are shown separately. The width of the dark (light) shaded bands depicts the statistical (total) uncertainty.

Figure 2

The genuine \pphi correlation function $C_{\pphi}(\kstar)$ with statistical (bars) and systematic uncertainties (boxes). The red band depicts the results from the fit employing the \Ledn . The width corresponds to one standard deviation of the uncertainty of the fit.