Lambda-p femtoscopy in collisions of Ar+KCl at 1.76 AGeV

TL;DR

This paper reports the first femtoscopy measurements of Lambda-proton correlations at 1.76 AGeV in Ar+KCl collisions, revealing a smaller emission source radius than in higher-energy heavy-ion collisions and establishing a linear relationship with system size.

Contribution

It provides the first femtoscopy analysis of Lambda-proton correlations at this low energy, offering new insights into the space-time characteristics of particle emission in such collisions.

Findings

Lambda-proton source radius is slightly smaller than proton-proton radius in similar systems.

Lambda-proton radius is smaller than in high-energy heavy-ion collisions but larger than in electroproduction.

Lambda-proton source radius increases linearly with the cube root of the number of participants.

Abstract

Results on $\Lambda$p femtoscopy are reported at the lowest energy so far. At a beam energy of 1.76A~GeV, the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\Lambda$ sample was collected, allowing for the investigation of $\Lambda$ p correlations at small relative momenta. The experimental correlation function is compared to corresponding model calculations allowing the determination of the space-time extent of the $\Lambda$p emission source. The $\Lambda$p source radius is found slightly smaller than the pp correlation radius for a similar collis ion system. The present $\Lambda$p radius is significantly smaller than that found for Au+Au/Pb+Pb collisio ns in the AGS, SPS and RHIC energy domains, but larger than that observed for electroproduction from He. Taking into account all available data, we find the $\Lambda$p source radius to increase almost linearly with the number of participants to the power of one-third.