scholarly journals A unified quark-nuclear matter equation of state from the cluster virial expansion within the generalized Beth–Uhlenbeck approach

2021 ◽  
Vol 57 (1) ◽  
Author(s):  
Niels-Uwe Friedrich Bastian ◽  
David Bernhard Blaschke
Keyword(s):  
Phase Diagram ◽  
Phase Shift ◽  
Mean Field ◽  
Bound State ◽  
Strongly Correlated ◽  
Continuum Threshold ◽  
First Order Phase Transition ◽  
Mean Fields ◽  
First Order Phase ◽  
Transition Behaviour

AbstractWe consider a cluster expansion for strongly correlated quark matter where the clusters are baryons with spectral properties that are described within the generalized Beth–Uhlenbeck approach by a medium dependent phase shift. We employ a simple ansatz for the phase shift which describes an on-shell bound state with an effective mass and models the continuum by an anti-bound state located at the mass of the three-quark continuum threshold, so that the Levinson theorem is fulfilled by construction. The quark and baryon interactions are accounted for by the coupling to scalar and vector meson mean fields modelled by density functionals. At increasing density and temperature, due to the different medium-dependence of quark and baryon masses, the Mott dissociation of baryons occurs and its contributions to the thermodynamics vanish. It is demonstrated on this simple example that this unified approach to quark-hadron matter is capable of describing crossover as well as first order phase transition behaviour in the phase diagram with a critical endpoint. Changing the meson mean field, the case of a “crossover all over” in the phase diagram is also obtained.

QCD susceptibilities in the presence of the chiral chemical potential

2020 ◽  
Vol 35 (16) ◽  
pp. 2050137
Author(s):  
Run-Lin Liu ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Chemical Potential ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Chiral Phase ◽  
First Order Phase Transition ◽  
Phase Transition Region ◽  
First Order Phase

In this paper, chiral chemical potential [Formula: see text] is introduced to investigate the QCD susceptibilities and chiral phase transition within the Polyakov-loop-extended Nambu–Jona-Lasinio models in the mean-field approximation. We concentrate on the effect of chiral chemical potential on the phase diagram and the QCD susceptibilities. Moreover, it is worth noting that chiral chemical potential has more and more prominent impact on the susceptibilities and the phase diagram with the decrease of temperature based on our results, which coincides with the prediction that the chiral symmetry is dynamically broken in the first-order phase transition region and gets partly restored in the crossover region.

scholarly journals Low-temperature dielectric anomaly arising from electronic phase separation at the Mott insulator-metal transition

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
A. Pustogow ◽  
R. Rösslhuber ◽  
Y. Tan ◽  
E. Uykur ◽  
A. Böhme ◽  
...  
Keyword(s):  
Phase Separation ◽  
Mean Field Theory ◽  
Mean Field ◽  
Coulomb Repulsion ◽  
Mott Insulator ◽  
Electronic Phase Separation ◽  
First Order Phase Transition ◽  
Electronic Phase ◽  
Insulator Metal Transition ◽  
First Order Phase

AbstractCoulomb repulsion among conduction electrons in solids hinders their motion and leads to a rise in resistivity. A regime of electronic phase separation is expected at the first-order phase transition between a correlated metal and a paramagnetic Mott insulator, but remains unexplored experimentally as well as theoretically nearby T = 0. We approach this issue by assessing the complex permittivity via dielectric spectroscopy, which provides vivid mapping of the Mott transition and deep insight into its microscopic nature. Our experiments utilizing both physical pressure and chemical substitution consistently reveal a strong enhancement of the quasi-static dielectric constant ε1 when correlations are tuned through the critical value. All experimental trends are captured by dynamical mean-field theory of the single-band Hubbard model supplemented by percolation theory. Our findings suggest a similar ’dielectric catastrophe’ in many other correlated materials and explain previous observations that were assigned to multiferroicity or ferroelectricity.

Thermodynamic properties of a spin-1 model with long-range interactions

2018 ◽  
Vol 32 (05) ◽  
pp. 1850053 ◽  
Author(s):  
Ji-Xuan Hou ◽  
Xu-Chen Yu
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Long Range ◽  
Order Phase Transition ◽  
First Order ◽  
First Order Phase Transition ◽  
Long Range Interactions ◽  
External Magnetic Field Strength ◽  
First Order Phase

The long-range interacting spin-1 chain placed in a staggered magnetic field is studied by means of microcanonical approach. Firstly, we study the microcanonical entropy of the system in the thermodynamic limit and find the system is non-ergodic and can exhibit either first-order phase transition or second-order phase transition by shifting the external magnetic field strength. Secondly, we construct the global phase diagram of the system and find a phase transition area in the phase diagram corresponding to the temperature jump of the first-order phase transition.

scholarly journals Finite-Temperature Bose-Einstein Condensation in Interacting Boson System

2019 ◽  
Vol 64 (12) ◽  
pp. 1118
Author(s):  
D. Anchishkin ◽  
I. Mishustin ◽  
O. Stashko ◽  
D. Zhuravel ◽  
H. Stoecker
Keyword(s):  
Chemical Potential ◽  
Bose Condensate ◽  
Mean Field ◽  
Einstein Condensation ◽  
Total Density ◽  
Boson System ◽  
First Order Phase Transition ◽  
The Mean ◽  
Bose Einstein ◽  
First Order Phase

Thermodynamical properties of an interacting boson system at finite temperatures and zero chemical potential are studied within the framework of the Skyrme-like mean-field toy model. It is assumed that the mean field contains both attractive and repulsive terms. Self-consistency relations between the mean field and thermodynamic functions are derived. It is shown that, for sufficiently strong attractive interactions, this system develops a first-order phase transition via the formation of a Bose condensate. An interesting prediction of the model is that the condensed phase is characterized by a constant total density of particles. It is shown that the energy density exhibits a jump at the critical temperature.

A FIRST ORDER PHASE TRANSITION IN ISING FERRIMAGNETS

1995 ◽  
Vol 09 (21) ◽  
pp. 1347-1351 ◽  
Author(s):  
HASAN M. AL MUKADAM ◽  
DIMO I. UZUNOV
Keyword(s):  
Phase Transition ◽  
Order Parameter ◽  
Mean Field Theory ◽  
Mean Field ◽  
First Order ◽  
First Order Phase Transition ◽  
Exchange Constants ◽  
The Mean ◽  
First Order Phase ◽  
Ising Spins

The mean field theory is used for the analysis of a two-sublattice system of Ising spins, which describes ferro-, antiferro-, and ferrimagnetic orderings. It is proven that the phase transition in these systems is of a first order when the exchange constants of the sublattices are different. The free energy, the order parameter profiles and the latent heat of the phase transition are calculated for almost equivalent sublattices.

scholarly journals Critical end point in a thermomagnetic nonlocal NJL model

2017 ◽  
Vol 32 (26) ◽  
pp. 1750162 ◽  
Author(s):  
F. Márquez ◽  
R. Zamora
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Phase Transition ◽  
Chemical Potential ◽  
First Order ◽  
End Point ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
The Magnetic Field

In this paper, we explore the critical end point in the [Formula: see text] phase diagram of a thermomagnetic nonlocal Nambu–Jona-Lasinio model in the weak field limit. We work with the Gaussian regulator, and find that a crossover takes place at [Formula: see text], [Formula: see text]. The crossover turns to a first-order phase transition as the chemical potential or the magnetic field increases. The critical end point of the phase diagram occurs at a higher temperature and lower chemical potential as the magnetic field increases. This result is in accordance to similar findings in other effective models. We also find that there is a critical magnetic field, for which a first-order phase transition takes place even at [Formula: see text].

scholarly journals Metal-insulator Phase Diagram for the Fully Diagonal Disordered Hubbard Model at Half-filling

2016 ◽  
Vol 26 (2) ◽  
pp. 159
Author(s):  
Hoang Anh Tuan ◽  
Nguyen Thi Hai Yen
Keyword(s):  
Phase Diagram ◽  
Mean Field Theory ◽  
Mean Field ◽  
Metallic State ◽  
Strongly Correlated ◽  
Potential Approximation ◽  
Metal Insulator ◽  
Band Insulator ◽  
Half Filling ◽  
Correlation Strength

The electronic properties of strongly correlated systems with binary type of disorder are investigated using the coherent potential approximation. For half-filled system, two transitions from a band insulator via a metallic state to a Mott insulator are found with increasing the correlation strength of only one of the constituents. Our phase diagram is consistent with those obtained by the dynamical mean field theory.

Notizen: Monte-Carlo Simulation of a Two-dimensional Dipolar Lattice

1977 ◽  
Vol 32 (11) ◽  
pp. 1320-1322 ◽  
Author(s):  
S. Romano
Keyword(s):  
Monte Carlo ◽  
Mean Field Theory ◽  
Mean Field ◽  
Square Lattice ◽  
Electrostatic Energy ◽  
Two Dimensional ◽  
First Order ◽  
First Order Phase Transition ◽  
The Mean ◽  
First Order Phase

Abstract Monte-Carlo calculations were carried out on a system consisting of 256 point-dipoles, whose centres are fixed in a two-dimensional square lattice with the usual boundary con­dition; the Epstein-Ewald-Kornfeld algorithm was used in evaluating the electrostatic energy. No evidence of a first-order phase transition was found, and the results suggest there might be a second-order one. Additional calculations were carrierd out using the mean-field theory, which was found to overestimate the transition temperature by about a factor two.

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