Measurement of the p– Σ + correlation function in pp collisions at s = 13 TeV

In this letter, the first measurement of the femtoscopic correlation of protons and Σ + hyperons is presented and used to study the p– Σ + interaction. The measurement is performed with the ALICE detector in high-multiplicity triggered pp collisions at s = 13 TeV. The Σ + hyperons are reconstructed using a missing-mass approach in the decay channel to p + π 0 with π 0 → γ γ , while both Σ + and protons are identified using a machine learning approach. These techniques result in a high reconstruction efficiency and purity, which allows the measurement of the p– Σ + correlation function for the first time. Thanks to the high significance achieved in the p– Σ + correlation signal, it is possible to discriminate between the predictions of different models of the N–Σ interaction and to accomplish a first determination of the p– Σ + scattering parameters.