Novel constraints on \(\varLambda \text{-- }\overline{\varLambda }\) and \(p\text{-- }\overline{\varLambda }\) interactions using correlation data

Abstract

The interaction between baryons and antibaryons () remains a fundamental topic in hadronic physics, particularly due to its potential to reveal exotic bound states such as baryonia. While the proton–antiproton (\(p\text{-- }\bar{p}\)) system has been extensively studied – mainly via scattering experiments – the interactions involving antihyperons, such as proton–antilambda (\(p\text{-- }\overline{\varLambda }\)) and lambda–antilambda (\(\varLambda \text{-- }\overline{\varLambda }\)), are still poorly constrained due to the scarcity of experimental data. High-precision data on these systems, covering the low-energy region down to zero momentum, have recently been obtained via femtoscopic measurements in small colliding systems at the LHC. These results offer a unique opportunity to probe these interactions at short distances with unprecedented precision. In this work, we extract for the first time the scattering parameters for the \(\varLambda \text{-- }\overline{\varLambda }\) and \(p\text{-- }\overline{\varLambda }\) systems by exploiting high-precision correlation data measured by the ALICE experiment in pp collisions. The goal is to investigate potential differences in the interplay between the elastic and annihilation components of the interaction potential. We employ a novel correlation analysis framework, the imaginary CATS (iCATS) package, which solves exactly the Schrödinger equation with complex optical potentials to model the strong final-state interactions (FSI) in systems dominated by inelastic processes, as is typical in the case. Our results indicate distinct annihilation characteristics between the \(p\text{-- }\overline{\varLambda }\) and \(\varLambda \text{-- }\overline{\varLambda }\) systems, challenging the assumption of a universal dynamics. The extracted scattering amplitudes are compared to available production cross sections and invariant mass spectra involving \(p\text{-- }\overline{\varLambda }\) and \(\varLambda \text{-- }\overline{\varLambda }\) pairs. The \(\varLambda \text{-- }\overline{\varLambda }\) and \(p\text{-- }\overline{\varLambda }\) FSI constrained to femtoscopic data deliver an overall consistent agreement for all these observables, indicating the possibility to explore the sector more in details in future correlation measurements.