Speaker
Description
Systems such as $\mathrm{K^- p}$ and baryon--antibaryon ($\mathrm{B\overline{B}}$) are both characterized by the presence of strong inelastic channels at the production threshold, which can affect the properties and the formation of bound states and resonances.\
In the $\mathrm{\overline{K}N}$ system, the $\Lambda(1405)$ arises from the interplay between the $\mathrm{\overline{K}N}$ and the coupled $\Sigma\pi$ channel. Experimental constraints on the different $\mathrm{\overline{K}N}$ coupled-channels are needed to provide a full description of the nature and properties of the $\Lambda(1405)$. Similarly, baryon–antibaryon systems are characterised by the dominant contribution of several mesonic channels related to the presence of annihilation processes acting below 1 fm. The possible existence of baryon--antibaryon bound states is still under debate because of the limited amount of data available for the $\mathrm{p-\overline{p}}$ system, and either scarce or absent experimental data for $\mathrm{B\overline{B}}$ systems containing strangeness.
The femtoscopy technique measures the correlation of particle pairs at low relative momentum. This method has been applied in small colliding systems, such as pp and p--Pb collisions at ALICE, and provided high-precision data on several baryon--baryon and meson--baryon pairs, showing a great sensitivity to the underlying strong potential and to the introduction of the different coupled-channels.\
In this talk, we will present femtoscopic correlations measured by ALICE in pp collisions at $\sqrt{s}=13$ TeV, separately for data samples obtained with minimum-bias and high-multiplicity triggers, and in peripheral and ultra--peripheral p--Pb and Pb--Pb collisions at $\sqrt{s}=5.02$ TeV.
In particular, we will show results on the $\mathrm{K^- p}$ correlation function which for the first time provide experimental evidence of the opening of the coupled isospin breaking channel $\mathrm{\overline{K^0}-n}$ and on the $\Sigma\pi$ channel contributions. Finally, results from baryon--antibaryon pairs ($\mathrm{p\overline{p}}$, $\mathrm{p\overline{\Lambda}}$ and $\mathrm{\Lambda\overline{\Lambda}}$) will be shown for the first time. The effect of annihilation channels on the correlation function and a quantitative determination of the inelastic contributions in the three different pairs will be discussed.
