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+π0 with π0→γγ, 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.