# Electron correlations in the antiproton energy loss distribution in He

## TL;DR

This paper presents ab-initio calculations of electron energy transfer in helium caused by antiprotons, revealing that electron correlation effects significantly influence stopping and straggling, with straggling surpassing the Bohr limit due to shake-up processes.

## Contribution

The study introduces detailed ab-initio calculations highlighting the impact of electron correlations on antiproton energy loss in helium, surpassing previous mean-field approximations.

## Key findings

- Electron correlations significantly affect energy transfer cross-sections.
- Straggling exceeds the Bohr limit when shake-up processes are included.
- Correlation effects are crucial for accurate modeling of antiproton interactions.

## Abstract

We present ab-initio calculations of the electronic differential energy transfer (DET) cross-sections for antiprotons with energies between $3$keV and $1$MeV interacting with helium. By comparison with simulations employing the mean-field description based on the single-active electron approximation we are able to identify electron correlation effects in the stopping and straggling cross sections. Most remarkably, we find that straggling exceeds the celebrated Bohr straggling limit when correlated shake-up processes are included.