Meson-baryon systems with strangeness content provide a unique laboratory for investigating the strong interaction and testing theoretical models of hadron structure and dynamics. In this work, the measured correlation functions for oppositely charged $\Xi-{\rm K}$ and $\Xi-\pi$ pairs obtained in high-multiplicity pp collisions at $\sqrt{s} = 13$ TeV at the LHC are presented. For the first time, high-precision data on the $\Xi-{\rm K}$ interaction are delivered at small relative momenta. The scattering lengths, extracted via the Lednick\'y-Lyuboshits expression of the pair wavefunction, indicate a repulsive and a shallow attractive strong interaction for the $\Xi-{\rm K}$ and $\Xi-\pi$ systems, respectively. The $\Xi(1620)$ and $\Xi(1690)$ states are observed in the $\Xi-\pi$ correlation function and their properties, mass and width, are determined. These measurements are in agreement with other available results. Such high-precision data can help refine the understanding of these resonant states, provide stronger constraints for chirally motivated potentials, and address the key challenge of describing the coupled-channel dynamics that may give rise to molecular configurations.
Submitted to: PLB
e-Print: arXiv:2509.24519 | PDF | inSPIRE
Figure group
Figure 1
Measured correlation function of \XiK pairs. Data are represented by the black circles, with statistical (black vertical lines) and systematic (orange boxes) uncertainties shown separately The pink and blue bands represent the results from the fit considering strong and Coulomb FSI via the LL approach and the BCN model, respectively The gray band represents the mini-jet background associated with the LL fit The green line represents the Coulomb-only assumption The lower panel presents the difference between the data and the modeled correlation functions for the LL (pink) and BCN (blue) models expressed as the number of standard deviations, n$\sigma$. |  |
Figure 3
Measured correlation function of \XiPi pairs. Statistical (bars) and systematic (boxes) uncertainties are shown separately. The pink band represents the fit with both Coulomb and strong interactions via the LL approach, while the green band indicates the Coulomb-only results. The $C_\mathrm{background} (\kstar)$ within the Coulomb + strong fit is reported in gray. The inset shows a zoomed-in view of the y-axis, highlighting the \ks region of the \XRes and \XResNovanta states in greater detail. The lower panel presents the difference between the data and the modeled correlation functions using Coulomb and strong interactions (pink) and Coulomb only (green) expressed as the number of standard deviations, n$\sigma$. |  |
Figure 4
Genuine \XiPi correlation function. Statistical (bars) and systematic (boxes)uncertainties are shown separately. The pink band represents the genuine theoretical correlation function obtained with both Coulomb and strong interactions. The inset shows a zoomed-in view of the y-axis, highlighting the \ks region of the \XRes and \XResNovanta states in greater detail. |  |
Figure A.1
Region of the measured \XiPi correlation corresponding to the production of $\XicZero$ decaying into \XiPi pairs. Left: results assuming only the presence of the \Xic state. Right: results assuming also the presence of the \XResDuemila state. The pink band represents the fit with Eq. \ref{eq:FitXic}, the polynomial background is given by the grey band. In blue and red, the center values of the profile shape of the \XResDuemila and \XicZero are shown, respectively. |  |
Figure A.2
Measured correlation function of \XiK pairs in the whole fit range. Statistical (bars) and systematic (boxes)uncertainties are shown separately. The pink band represents the fit with both Coulomb and strong interaction using the LL method. The $C_\mathrm{background} (\kstar)$ multiplied by the normalization constant $N_D$ obtained within the Coulomb + strong fit is reported in gray. |  |
Figure A.3
Measured correlation function of \XiPi pairs in the whole fit range. Statistical (bars) and systematic (boxes) uncertainties are shown separately. The pink band represents the fit with both Coulomb and strong interaction using the LL method,. The $C_\mathrm{background} (\kstar)$ multiplied by the normalization constant $N_D$ obtained within the Coulomb + strong fit is reported in gray. The inset shows a zoomed-in view of the y-axis, highlighting the \ks region of the \XRes and \XResNovanta states in greater detail. |  |