# Cold QCD at finite isospin density: confronting effective models with recent lattice data

## TL;DR

This paper calculates the QCD equation of state at zero temperature and finite isospin density using the Nambu-Jona-Lasinio model, comparing results with recent lattice QCD data relevant for pion stars.

## Contribution

It introduces a comparison of regularization schemes within the NJL model and confronts effective model predictions with recent lattice QCD results for isospin-rich matter.

## Key findings

- NJL model results align with lattice data for pion stars
- Medium separation scheme improves regularization consistency
- Effective models can describe finite isospin density phenomena

## Abstract

We compute the QCD equation of state for zero temperature and finite isospin density within the Nambu-Jona-Lasinio model in the mean field approximation, motivated by the recently obtained Lattice QCD results for a new class of compact stars: pion stars. We have considered both the commonly used Traditional cutoff Regularization Scheme and the Medium Separation Scheme, where in the latter purely vacuum contributions are separated in such a way that one is left with ultraviolet divergent momentum integrals depending only on vacuum quantities. We have also compared our results with the recent results from Lattice QCD and Chiral Perturbation Theory.