38 ALICE Collaboration ALI DTL CIT EXM ALICE@CERN Investigating the nature of the K$^*_0(700)$ state with $\pi^\pm$K$^0_{\rm S}$ correlations at the LHC 10.17182/HEPDATA.153749 English Investigating the nature of the K$^*_0(700)$ state with $\pi^\pm$ K$^0_{\rm S}$ correlations at the LHC. -- The first measurements of femtoscopic correlations with the particle pair combinations $\pi^\pm$ K$^0_{\rm S}$ in pp collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider are reported by the ALICE experiment. Using the femtoscopic approach, it is shown that it is possible to study the elusive K$^*_0(700)$ particle that has been considered a tetraquark candidate for over forty years. Boson source parameters and final-state interaction parameters are extracted by fitting a model assuming a Gaussian source to the experimentally measured two-particle correlation functions. The final-state interaction is modeled through a resonant scattering amplitude, defined in terms of a mass and a coupling parameter, decaying into a $\pi^\pm$K$^0_{\rm S}$ pair. The extracted mass and Breit--Wigner width, derived from the coupling parameter, of the final-state interaction are found to be consistent with previous measurements of the K$^*_0(700)$. The small value and increasing behavior of the correlation strength with increasing source size support the hypothesis that the K$^*_0(700)$ is a four-quark state, i.e. a tetraquark state. This latter trend is also confirmed via a simple geometric model that assumes a tetraquark structure of the K$^*_0(700)$ resonance. Journal Article GSI record: GSI-2025-00244 ; Dataset 2024 GSI-2025-00245 2024 https://repository.gsi.de/record/356862 https://doi.org/10.17182/HEPDATA.153749