Relativistic Phase Transitions Research Articles

From the Early Universe to the Modern Universe

The birth of the Universe, its dark components, and the next fundamental level of matter are briefly discussed. The classical cosmological solution for our Universe with a Λ-term has two branches divided by a gap. The quantum process of tunneling between branches took place. A model of a slowly swelling Universe in the result of the multiple reproductions of cosmological cycles arises naturally. The occurrence of baryon asymmetry is briefly discussed. The problem of the cosmological constant is solved and, thus, the crisis of physics connected with this constant is overcome. But we note that dark energy is evolving. Dark matter (part or all) consists of familon-type pseudo-Goldstone bosons with a mass of 10−5–10−3 eV. It follows the composite model of particles. This model reproduces three relativistic phase transitions in the medium of familons at different red shifts, forming a large scale structure of the Universe dark matter that was “repeated” by baryons. Here three generations of elementary particles are absolutely necessary.

Relativistic gravitational phase transitions and instabilities of the Fermi gas

We describe microcanonical phase transitions and instabilities of the ideal Fermi gas in general relativity at nonzero temperature confined in the interior of a spherical shell. The thermodynamic behaviour is governed by the compactness of rest mass, namely of the total rest mass over radius of the system. For a fixed value of rest mass compactness, we study the caloric curves as a function of the size of the spherical box. At low compactness values, low energies and for sufficiently big systems the system is subject to a gravothermal catastrophe, which cannot be halted by quantum degeneracy pressure, and the system collapses. For small systems, there appears no instability at low energies. For intermediate sizes, between two marginal values, gravothermal catastrophe is halted and a microcanonical phase transition occurs from a gaseous phase to a condensed phase with a nearly degenerate core. The system is subject to a relativistic instability at low energy, when the core gets sufficiently condensed above the Oppenheimer–Volkoff limit. For sufficiently high values of rest mass compactness the microcanonical phase transitions are suppressed. They are replaced either by an Antonov type gravothermal catastrophe for sufficiently big systems or by stable equilibria for small systems. At high energies the system is subject to the ‘relativistic gravothermal instability’, identified by Roupas (2015 Class. Quantum Grav. 32 135023), for all values of compactness and any size.

Highlights from the STAR experiment

The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) studies properties and phase transitions of nuclear matter in various nucleus-nucleus collisions at center-of-mass energies per nucleon collision sNN=7.7-200GeV. With a fixed target made of gold foils installed inside the beam pipe, STAR also starts to explore high baryon density regime (μB≈420-720MeV) at sNN=3.0-7.7GeV. A few selected results reported by the STAR collaboration at the Quark Matter 2018 (QM2018) conference are described in these proceedings.

The dark components of the Universe are slowly clarified

The dark sector of the Universe is beginning to be clarified step by step. If the dark energy is vacuum energy, then 123 orders are exactly reduced by ordinary physical processes. For many years these unexplained orders were called a crisis in physics. There was indeed a "crisis" before the introduction of the holographic principle and entropic force in physics. The vacuum energy was spent for the organization of new microstates during the entire life of the Universe, but in the initial period of its evolution the vacuum energy (78 orders) were reduced more effectively by the vacuum condensates produced by phase transitions, because the Universe lost the high symmetry during its expansion. Important problems of physics and cosmology can be solved if the quarks, leptons, and gauge bosons are composite particles. The dark matter, partially or all consisting of familon-type pseudo-Goldstone bosons with a mass of 10^{-5} - 10^{-3} eV, can be explained in the composite model. Three generations of elementary particles are absolutely necessary in this model. In addition, this model realizes three relativistic phase transitions in a medium of familons at different red shifts, forming a large-scale structure of dark matter that was "repeated" by baryons. We predict the detection of dark matter dynamics, the detection of familons as dark matter particles, and the development of spectroscopy for dark medium due to the probable presence of dark atoms in it. Other viewpoints on the dark components of the Universe are also discussed briefly.

Search for ultrashort gamma-ray bursts from evaporating primordial black holes

Cosmic gamma-ray bursts from evaporating primordial black holes for the evaporation model with relativistic phase transitions have been sought in the data from the Andyrchy extensive air shower (EAS) array. This model predicts ultrashort (≃10−13 s) gamma-ray bursts with the spectrum with the maximum intensities simultaneously at the photon energies of 100 MeV and 100 GeV. Such ultrashort gamma-ray bursts can be detected by EAS arrays located on mountains as EASs with a uniform lateral distribution. A limit on the concentration of evaporating primordial black holes in a local region of the Galaxy for this evaporation model has been obtained from information accumulated during a live time of 4.23 yr.

Quantum Simulation of the Majorana Equation and Unphysical Operations

A quantum simulator is a device engineered to reproduce the properties of an ideal quantum model. It allows the study of quantum systems that cannot be efficiently simulated on classical computers. While a universal quantum computer is also a quantum simulator, only particular systems have been simulated up to now. Still, there is a wealth of successful cases, such as spin models, quantum chemistry, relativistic quantum physics and quantum phase transitions. Here, we show how to design a quantum simulator for the Majorana equation, a non-Hamiltonian relativistic wave equation that might describe neutrinos and other exotic particles beyond the standard model. The simulation demands the implementation of charge conjugation, an unphysical operation that opens a new front in quantum simulations, including the discrete symmetries associated with complex conjugation and time reversal. Finally, we show how to implement this general method in trapped ions.

Effects of the cosmological expansion on the bubble nucleation rate for relativistic first-order phase transitions

I calculate the first corrections to the dynamical preexponential factor of the bubble nucleation rate for a relativistic first-order phase transition in an expanding cosmological background by estimating the effects of the Hubble expansion rate on the critical bubbles of Langer's statistical theory of metastability. I also comment on possible applications and problems that arise when one considers the field theoretical extensions of these results (the Coleman-De Luccia and Hawking-Moss instantons and decay rates)

Chirality quantum phase transition in the Dirac oscillator

We study a relativistic spin-1/2 fermion subjected to a Dirac oscillator coupling and a constant magnetic field. An interplay between opposed chirality interactions culminates in the appearance of a relativistic quantum phase transition, which can be fully characterized. We obtain analytical expressions for the energy gap, order parameter, and canonical quantum fluctuations across the critical point. Moreover, we also discuss the effect of this phase transition on the statistics of the chiral bosonic ensemble, where its super- or sub-Poissonian nature can be controlled by means of external parameters. Finally, we study the entanglement properties between the degrees of freedom in the relativistic ground state, where an interesting transition between a biseparable and a genuinely tripartite entangled state occurs.

Effects of multiplicative noise in relativistic phase transitions

Effective stochastic equations for the continuous transitions of relativistic quantum fields inevitably contain multiplicative noise. We examine the effect of such noise in a numerical simulation of a temperature quench in a 1+1 dimensional scalar theory. We look at out-of-equilibrium defect formation and compare our results with those of stochastic equations with purely additive noise.

Familon model of dark matter

If the next fundamental level of matter occurs (preons), then dark matter must consist of familons containing a ‘hot’ component from massless particles and a ‘cold’ component from massive particles. During the evolution of the Universe this dark matter occurred up to late-time relativistic phase transitions the temperatures of which were different. Fluctuations created by these phase transitions had a fractal character. As a result the structuration of dark matter (and therefore the baryon subsystem) occurred, and in the Universe some characteristic scales which have caused this phenomenon arise naturally. Familons are collective excitations of non-perturbative preon condensates that could be produced during an earlier relativistic phase transition. For structuration of dark matter (and the baryon component), three generations of particles are necessary. The first generation of particles produced the observed baryon world. The second and third generations produced dark matter from particles that appeared ...

New scenario for the early evolution of the Universe

We propose that the Universe was created from ``nothing'' with a relatively small number of particles and quickly relaxed to a quasiequilibrium state at the Planck parameters. The classic cosmological solution for this Universe with a $\ensuremath{\Lambda}$ term has two branches divided by a gap. The quantum process of tunneling between the cosmological solution branches and kinetics of the second order relativistic phase transition in a supersymmetric SU(5) model on GUT scale are investigated using numerical methods. The Einstein equations are solved together with the equations of relaxation kinetics. Another quantum geometrodynamics process (the bounce from a singularity) and the Wheeler-DeWitt equation are also investigated. The computer experiments show that because of the rapid character of the relaxation processes and the absence in the inflaton potential of peculiarities that are able to delay the system in the overcooled phase, the usual type of inflation regime is not realized. For the formation of the observed number of particles a model of a slowly swelling Universe as the result of the multiple reproduction of cosmological cycles arises naturally.

THE STUDY OF THE LARGE-SCALE STRUCTURE EVOLUTION OF THE UNIVERSE BY RADIOSPECTROSCOPY METHODS

On the basis of our theoretical speculations we propose to organize search observations of baryon structures at high redshifts (z > 5). We suggest a new observable strategy for the search of baryon structures in radiolines of simplest molecules OH and CH, which may produce the megamaser and gigamaser emission in very early epoches. The theoretical basis is the possibility of seed productions for baryon structures by a last relativistic phase transition in gas of pseudo-Gold-stone bosons at z ∼ 10-20.

THE TUNNELING, THE SECOND ORDER RELATIVISTIC PHASE TRANSITIONS AND PROBLEM OF THE MACROSCOPIC UNIVERSE ORIGIN

We propose that the Universe was created from “Nothing” with a relatively small number of particles and it very quick relaxed to a quasi-equilibrium state at the Planck parameters. The classic cosmological solution for this Universe, with the calculation of its ability to undergo the second order relativistic phase transition (RPT), has two branches divided by a gap. On one of these branches near to the “Nothing” state the second order RPT is not possible at the GUT scale. The other branch is thermodynamically unstable. The quantum process of tunneling between the cosmological solution branches and the kinetics of the second order RPT are investigated by numerical methods. Another quantum geometrodynamics process (bounce from singularity) is also taken into consideration. It is shown that the discussed phenomenon with the calculation of all RPTs from the GUT scale (1016 Gev) to the Salam-Weinberg scale (102 Gev) gives the new cosmological scenarios of the macroscopic Universe origin with the observable number of particles.

A MORE EXACT THEORY OF RELATIVISTIC PHASE TRANSITIONS OF THE EARLY UNIVERSE

This paper examines the thermodynamics of relativistic phase transitions in which the heterogeneity of the system (the vacuum condensate, scalar and vector particles) is considered evident. The given system does not have a united functional of state which is common to both low-symmetric and high-symmetric phases. The theory acquires the necessary physical content after the introduction of additional parameters of order identified with the parameters of the energetic spectrum (effective masses of particles), The many-parameter thermodynamics of relativistic phase transitions in heterogeneous systems changes the current conceptions about the character of these transitions and about the properties of the system near the critical point. For T>Tcrit the system of Higgs fields has no thermodynamical equilibrium states and it can evolve under stochastic laws only. For T<Tcrit the stochastic regime of evolution begins to relax to the local thermodynamical equilibrium regime.

Nucleation of relativistic first-order phase transitions.

We apply the general formalism of Langer to compute the nucleation rate for systems of relativistic particles with a zero or small baryon-number density and which undergo first-order phase transitions. In particular, we obtain an expression for the pre-exponential factor and it is proportional to the viscosity. The initial growth rate of a critical size bubble or droplet is limited by the ability of dissipative processes to transport latent heat away from the surface.

Nucleation of cosmological phase transitions

A simple model is used to describe the nucleation of bubbles during a first-order relativistic cosmological phase transition. It is shown that if the parameters governing the nucleating action vary as powers of cosmological background quantities (such as temperature), and if the action has a certain general functional form, then the characteristic size of bubbles when the transition ends is smaller than the Hubble length by a factor of at least 1/4 ln[TP/Tc], where TP is the Planck temperature and Tc is the transition temperature. It is therefore unlikely that black holes form if TP≫ Tc, or that perturbations in entropy or pressure caused by the bubbles have any significant direct effect on large-scale cosmological inhomogeneity or nucleosynthesis.

Gravitational Radiation from Relativistic Phase Transitions

A semi-Newtonian treatment of the generation and detection of gravitational waves is presented. This is used to estimate the gravitational radiation from relativistic increases in pressure. The results are applied to various astrophysical processes, and the corresponding ed. It is concluded that observable events at the galactic center must have yields in excess of 1 M sub solar . (auth)