First Measurement of $\Lambda$ Electroproduction off Nuclei in the Current and Target Fragmentation Regions

TL;DR

This paper presents the first measurements of $\\Lambda$ hyperon production in semi-inclusive deep-inelastic scattering off various nuclei, revealing significant nuclear medium interactions and providing new insights into nucleon and strange baryon structure.

Contribution

It introduces the first measurements of $\\Lambda$ multiplicity ratios and transverse momentum broadening across different nuclei in the current and target fragmentation regions.

Findings

Strong suppression of multiplicity ratio at high $z$

Enhanced transverse momentum broadening in heavy nuclei

Qualitative agreement with Giessen BUU transport model

Abstract

We report results of $\Lambda$ hyperon production in semi-inclusive deep-inelastic scattering off deuterium, carbon, iron, and lead targets obtained with the CLAS detector and the Continuous Electron Beam Accelerator Facility 5.014~GeV electron beam. These results represent the first measurements of the $\Lambda$ multiplicity ratio and transverse momentum broadening as a function of the energy fraction~($z$) in the current and target fragmentation regions. The multiplicity ratio exhibits a strong suppression at high~$z$~and~an enhancement at~low~$z$. The measured transverse momentum broadening is an order of magnitude greater than that seen for light mesons. This indicates that the propagating entity interacts very strongly with the nuclear medium, which suggests that propagation of diquark configurations in the nuclear medium takes place at least part of the time, even at high~$z$. The trends of these results are qualitatively described by the Giessen Boltzmann-Uehling-Uhlenbeck transport model, particularly for the multiplicity ratios. These observations will potentially open a new era of studies of the structure of the nucleon as well as of strange baryons.