# Efimov universality with Coulomb interaction

## TL;DR

This paper explores how Coulomb interactions affect Efimov universality in charged particle systems, showing that universality persists weakly but breaks down with strong Coulomb forces, with implications for nuclear alpha-cluster structures.

## Contribution

It introduces a generalized Efimov plot incorporating Coulomb effects and analyzes the transition from universal to non-universal behavior in charged systems.

## Key findings

- Universal features persist for weak Coulomb interaction
- Universal properties break down at strong Coulomb interaction
- Root-mean-square radii decrease and become more localized with increasing Coulomb strength

## Abstract

The universal properties of charged particles are modified by the presence of a long-range Coulomb interaction. We investigate the modification of Efimov universality as a function of the Coulomb strength using the Gaussian expansion method. The resonant short-range interaction is described by Gaussian potentials to which a Coulomb potential is added. We calculate binding energies and root mean square radii for the three- and four-body systems of charged particles and present our results in a generalised Efimov plot. We find that universal features can still be discerned for weak Coulomb interaction, but break down for strong Coulomb interaction. The root-mean-square radius plateaus at increasingly smaller values for strong Coulomb interaction and the probablity distributions of the states become more concentrated inside the Coulomb barrier. As an example, we apply our universal model to nuclei with an alpha-cluster substructure. Our results point to strong non-universal contributions in that sector.