scholarly journals The possibility of twin star solutions in a model based on lattice QCD thermodynamics

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
P. Jakobus ◽  
A. Motornenko ◽  
R. O. Gomes ◽  
J. Steinheimer ◽  
H. Stoecker
Keyword(s):  
Neutron Stars ◽  
Lattice Qcd ◽  
Model Equation ◽  
Compact Stars ◽  
Model Parameters ◽  
Bag Model ◽  
First Order ◽  
Stellar Masses ◽  
First Order Phase

AbstractThe properties of compact stars and in particular the existence of twin star solutions are investigated within an effective model that is constrained by lattice QCD thermodynamics. The model is modified at large baryon densities to incorporate a large variety of scenarios of first order phase transitions to a phase of deconfined quarks. This is achieved by matching two different variants of the bag model equation of state, in order to estimate the role of the Bag model parameters on the appearance of a second family of neutron stars. The produced sequences of neutron stars are compared with modern constrains on stellar masses, radii, and tidal deformability from astrophysical observations and gravitational wave analyses. It is found that those scenarios in our analysis, in which a third family of stars appeared due to the deconfinement transition, are disfavored from astrophysical constraints.

scholarly journals Fate of false vacua in holographic first-order phase transitions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Aldo L. Cotrone ◽  
Angel Paredes
Keyword(s):  
Phase Transitions ◽  
Chiral Symmetry ◽  
Metastable Phase ◽  
Chiral Symmetry Breaking ◽  
Model Parameters ◽  
Temperature Phase ◽  
Thin Wall ◽  
Critical Temperatures ◽  
First Order ◽  
First Order Phase

Abstract Using the holographic correspondence as a tool, we study the dynamics of first-order phase transitions in strongly coupled gauge theories at finite temperature. Considering an evolution from the large to the small temperature phase, we compute the nucleation rate of bubbles of true vacuum in the metastable phase. For this purpose, we find the relevant configurations (bounces) interpolating between the vacua and we compute the related effective actions. We start by revisiting the compact Randall-Sundrum model at high temperature. Using holographic renormalization, we compute the derivative term in the effective bounce action, that was missing in the literature. Then, we address the full problem within the top-down Witten-Sakai-Sugimoto model. It displays both a confinement/deconfinement and a chiral symmetry breaking/restoration phase transition which, depending on the model parameters, can happen at different critical temperatures. For the confinement/deconfinement case we perform the numerical analysis of an effective description of the transition and also provide analytic expressions using thick and thin wall approximations. For the chiral symmetry transition, we implement a variational approach that allows us to address the challenging non-linear problem stemming from the Dirac-Born-Infeld action.

Coupling between order parameter and compositional fluctuations in the irradiation induced monoclinic to tetragonal phase transition in pure zirconia.

2003 ◽  
Vol 792 ◽  
Author(s):  
D Simeone ◽  
G Baldinozzi ◽  
D. Gosset ◽  
M. Dutheil
Keyword(s):  
Phase Transition ◽  
Tetragonal Phase ◽  
First Order ◽  
Nuclear Plants ◽  
First Order Phase Transition ◽  
Pure Zirconia ◽  
The Stability ◽  
First Order Phase ◽  
Tetragonal Phase Transition

ABSTRACTZirconia, oxidation product of Zircaloy cladding elements of nuclear plants, exhibits an unusual behaviour under irradiation. Impinging ions and neutrons induce a monoclinic to tetragonal phase transition at room temperature in this solid. To understand this modification of the positions of the stability lines in such a solid under irradiation, we have studied the monoclinic to tetragonal first order phase transition versus temperature in pure micrometric and nanometric zirconia samples. From these works, it was possible to understand the behaviour of this material under irradiation pointing out the key role of defects induced irradiation on its phase diagram.

Determination of the low-temperature structure of hexamethylbenzene

2005 ◽  
Vol 61 (2) ◽  
pp. 200-206 ◽  
Author(s):  
John A. Stride
Keyword(s):  
Low Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Thermally Induced ◽  
First Order ◽  
Neutron Powder Diffraction Data ◽  
First Order Phase Transition ◽  
First Order Phase

The low-temperature structure of hexamethylbenzene has been determined from neutron powder diffraction data and found to differ from the room-temperature phase predominantly by a translation of molecular planes to a form a cubic close-packed type structure. By performing measurements as a function of temperature, the role of thermally induced agitation of the molecular units in the first-order phase transition is clearly demonstrated.

Role of nucleation in the development of first-order phase transformations

2015 ◽  
Vol 6 (4) ◽  
pp. 283-288 ◽  
Author(s):  
A. E. Gvozdev ◽  
N. N. Sergeyev ◽  
I. V. Minayev ◽  
I. V. Tikhonova ◽  
A. G. Kolmakov
Keyword(s):  
Phase Transformations ◽  
First Order ◽  
First Order Phase

scholarly journals Dark holograms and gravitational waves

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Aldo L. Cotrone ◽  
Angel Paredes
Keyword(s):  
Phase Transitions ◽  
Gravitational Waves ◽  
Chiral Symmetry Breaking ◽  
Power Spectra ◽  
Model Parameters ◽  
Sound Waves ◽  
Critical Temperatures ◽  
Two Phase ◽  
First Order ◽  
First Order Phase

Abstract Spectra of stochastic gravitational waves (GW) generated in cosmological first-order phase transitions are computed within strongly correlated theories with a dual holographic description. The theories are mostly used as models of dark sectors. In particular, we consider the so-called Witten-Sakai-Sugimoto model, a SU(N) gauge theory coupled to different matter fields in both the fundamental and the adjoint representations. The model has a well-known top-down holographic dual description which allows us to perform reliable calculations in the strongly coupled regime. We consider the GW spectra from bubble collisions and sound waves arising from two different kinds of first-order phase transitions: a confinement/deconfinement one and a chiral symmetry breaking/restoration one. Depending on the model parameters, we find that the GW spectra may fall within the sensibility region of ground-based and space-based interferometers, as well as of Pulsar Timing Arrays. In the latter case, the signal could be compatible with the recent potential observation by NANOGrav. When the two phase transitions happen at different critical temperatures, characteristic spectra with double frequency peaks show up. Moreover, in this case we explicitly show how to correct the redshift factors appearing in the formulae for the GW power spectra to account for the fact that adiabatic expansion from the first transition to the present times cannot be assumed anymore.

scholarly journals On the Role of Mesoentropy in Thermodynamics of First Order Phase Transformations in Alloys

2015 ◽  
Vol 16 (1) ◽  
pp. 20-27
Author(s):  
A. Shirinyan
Keyword(s):  
Size Distribution ◽  
Energy Functional ◽  
Size Distribution Function ◽  
First Order ◽  
General Variation ◽  
The Difference ◽  
First Order Phase ◽  
New Phase

A thermodynamics of a new phase formation in a binary alloy, taking into account the chemical depletion and the size distribution of new phase nuclei giving the energy input at high temperatures, is considered. It is shown the principal possibility of obtaining of the size distribution function for nuclei in the framework of a general variation procedure for the Gibbs free energy functional. The ‘chemical depletion’ related to the difference of compositions of the new phase embryo and the solution of the solid metastable alloy is discussed. The role of the ‘mesoentropy’ for the determination of whole energy of first order phase transformation is manifested.

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