https://doi.org/10.1140/epja/s10050-023-01169-3
Regular Article - Theoretical Physics
Robust features of a QCD phase diagram through a contact interaction model for quarks: a view from the effective potential
1
Institute of Physics, Gomal University, 29220, D.I. Khan, Khyber Pakhtunkhaw, Pakistan
2
Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, 58040, Morelia, Michoacán, México
3
Centro de Ciencias Exactas, Universidad del Bio-Bio, Avda. Andrés Bello 720, Casilla 447, Chillán, Chile
Received:
25
August
2023
Accepted:
14
October
2023
Published online:
3
November
2023
Our research delves into the quantum chromodynamics (QCD) phase diagram in the temperature T and quark chemical potential 
plane. We use a unique confining contact interaction effective model of quark dynamics that maintains the QCD symmetry intact. By embedding the model in a Schwinger–Dyson equation framework within a Landau gauge rainbow-ladder-like truncation, we derive the gap equation. In order to accurately regulate the equation, we utilize the Schwinger optimal time regularization scheme. We further derive the effective potential of the model by integrating the gap equation over the dynamical mass, which along with the confining length scale serve as parameters for the chiral and confinement–deconfinement phase transitions, respectively. A crossover transition is observed at low and above a critical value of the temperature 
, whilst a first-order phase transition is found for low T at high density. The location of the critical endpoint is estimated at 
, which falls within the range of other QCD effective model predictions. 
MeV is the critical temperature at vanishing . Screening effects of the medium which dilute the strength of the effective coupling are considered by including in the framework the vacuum polarization contribution due to quarks at high temperatures. The critical endpoint is then located at 
, which suggests the need for a deeper analysis of the screening effects on models of this kind.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
