# Impurity self-energy in the strongly-correlated Bose systems

## TL;DR

This paper introduces a non-perturbative path-integral method to calculate impurity spectra in strongly-correlated Bose systems, validated by experiments and simulations.

## Contribution

It presents a novel non-perturbative approach for impurity spectrum calculation in Bose systems using path-integral formulation.

## Key findings

- Consistent with experimental data for $^3$He in liquid helium-4
- Aligns with Monte Carlo simulation results
- Provides a new framework for impurity analysis in Bose systems

## Abstract

We proposed the non-perturbative scheme for calculation of the impurity spectrum in the Bose system at zero temperature. The method is based on the path-integral formulation and describes an impurity as a zero-density ideal Fermi gas interacting with Bose system for which the action is written in terms of density fluctuations. On the example of the $^3$He atom immersed in the liquid helium-4 a good consistency with experimental data and results of Monte Carlo simulations is shown.