Density screening effects in the NJL model: Chiral condensate, speed of sound, and the Critical End Point

Fuente: arXiv
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Autori principali: Díaz, Alejandro Rosas, Raya, Alfredo, Araujo, C. A. Vaquera, Hernández-Ortiz, S.
Natura: Preprint
Pubblicazione: 2026
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author Díaz, Alejandro Rosas
Raya, Alfredo
Araujo, C. A. Vaquera
Hernández-Ortiz, S.
author_facet Díaz, Alejandro Rosas
Raya, Alfredo
Araujo, C. A. Vaquera
Hernández-Ortiz, S.
contents The phase diagram of Quantum Chromodynamics (QCD) remains a central topic in high-energy physics. At high temperature and low baryochemical potential, the chiral transition is experimentally observed and theoretically explored to be a smooth crossover, while at high densities, a first-order phase transition is theoretically expected in lack of direct experimental evidence. The search for the Critical End Point (CEP), where both regimes meet, is one of the main objectives of heavy-ion experiments at FAIR and NICA. In this work, we explore the QCD phase diagram structure using the Nambu--Jona-Lasinio (NJL) model, incorporating medium screening effects through an effective coupling $G(T,μ)$ for $μ\gg T\sim 0$. We apply a consistent regularization scheme and Sommerfeld expansion to include low thermal and large density corrections in the gap equation. Our numerical analysis focuses on the behavior of the chiral condensate, the dynamical quark mass, and the speed of sound. We find that screening effects shift the posible position of the CEP and modify the nature of the chiral transition. These findings provide theoretical support for ongoing experimental searches and may have implications for the physics of compact stars.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26924
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Density screening effects in the NJL model: Chiral condensate, speed of sound, and the Critical End Point
Díaz, Alejandro Rosas
Raya, Alfredo
Araujo, C. A. Vaquera
Hernández-Ortiz, S.
High Energy Physics - Phenomenology
High Energy Physics - Theory
Nuclear Theory
The phase diagram of Quantum Chromodynamics (QCD) remains a central topic in high-energy physics. At high temperature and low baryochemical potential, the chiral transition is experimentally observed and theoretically explored to be a smooth crossover, while at high densities, a first-order phase transition is theoretically expected in lack of direct experimental evidence. The search for the Critical End Point (CEP), where both regimes meet, is one of the main objectives of heavy-ion experiments at FAIR and NICA. In this work, we explore the QCD phase diagram structure using the Nambu--Jona-Lasinio (NJL) model, incorporating medium screening effects through an effective coupling $G(T,μ)$ for $μ\gg T\sim 0$. We apply a consistent regularization scheme and Sommerfeld expansion to include low thermal and large density corrections in the gap equation. Our numerical analysis focuses on the behavior of the chiral condensate, the dynamical quark mass, and the speed of sound. We find that screening effects shift the posible position of the CEP and modify the nature of the chiral transition. These findings provide theoretical support for ongoing experimental searches and may have implications for the physics of compact stars.
title Density screening effects in the NJL model: Chiral condensate, speed of sound, and the Critical End Point
topic High Energy Physics - Phenomenology
High Energy Physics - Theory
Nuclear Theory
url https://arxiv.org/abs/2603.26924