Search for a common baryon source in high-multiplicity pp collisions at the LHC

We report on the measurement of the size of the particle-emitting source from two-baryon correlations with ALICE in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV. The source radius is studied with low relative momentum p-p, $\bar{\rm{p}}$-$\bar{\rm{p}}$, p-$\Lambda$ and $\bar{\rm{p}}$-$\bar{\Lambda}$ pairs as a function of the pair transverse mass $m_{\rm{T}}$ in the range (1.1-2.2) GeV/$c^{2}$. The larger masses of the studied particles enables the exploration of terra incognita in elementary systems at large $m_{\rm{T}}$. Regardless of the pair, the femtoscopic radii under the premise of a Gaussian source decrease with increasing $m_{\rm{T}}$ range by as much as 30%, and deviate among the investigated particle species. We implement for the first time in a quantitative way the concept of a core, a common emission profile of all particles, and a corona, a deformation due to strong resonance decays. Explicitly treating the latter reduces the magnitude of the core radii by up to 20% and the same dependence on $m_{\rm{T}}$ is observed for pairs of different particle species. This in turn indicates that protons, antiprotons, $\Lambda$, and $\bar{\Lambda}$ in these pp collisions originate from the same source. The invariant radius of this common source varies between 0.85 and 1.3 fm, which provides a precise reference for studies of the strong hadron-hadron interactions and for the investigation of collective properties in small colliding systems.