Symmetry structure and phase transitions (original) (raw)
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Non-Equilibrium Dynamics of Phase Transitions: From the Early Universe to Chiral Condensates
1994
In this brief review we introduce the methods of quantum field theory out of equilibrium and study the non-equilibrium aspects of phase transitions. Specifically we critically study the picture of the ``slow-roll'' phase transition in the new inflationary models, we show that the instabilities that are the hallmark of the phase transition, that is the formation of correlated domains, dramatically change this picture. We analyze in detail the dynamics of phase separation in strongly supercooled phase transitions in Minkowski space. We argue that this is typically the situation in weakly coupled scalar theories. The effective evolution equations for the expectation value and the fluctuations of an inflaton field in a FRW cosmology are derived both in the loop expansion and in a self-consistent non-perturbative scheme. Finally we use these non-equilibrium techniques and concepts to study the influence of quantum and thermal fluctuations on the dynamics of a proposed mechanism for the formation of disoriented chiral condensates during a rapid phase transition out of equilibrium. This last topic may prove to be experimentally relevant at present accelerator energies. To appear in the Proceedings of the `2nd. Journ\'ee Cosmologie', Observatoire de Paris, 2-4, June 1994. H J de Vega and N. S\'anchez, Editors, World Scientific.
Symmetries,Dynamical Evolution of Phase Transition and Nugget Formation
We study the influence of the presence of a magnetic field on chiral symmetry in the core of compact stars and in the early Universe. We find that the effect of a magnetic field is to enhance the chiral symmetry breaking in the sense that, in the presence of magnetic field, chiral symmetry gets restored at a higher temperature and density compared to the case where there is no magnetic field. However, the effect of a super strong magnetic field is to restore again chiral symmetry. We then investigate the dynamical evolution of the confinement-deconfinement phase transition in the expanding early Universe through bubble nucleation, taking into account reheating due to the heat released during the expansion of hadronic bubbles. We estimate the degree of supercooling and the time required to complete the phase transition. We then consider the formation of quark nuggets and their possible survival against boiling and evaporation to the present epoch.
Physical Review D, 2011
We investigate chiral symmetry breaking in strong magnetic fields at finite temperature and densities in a 3 flavor Nambu Jona Lasinio (NJL) model including the Kobayashi Maskawa t-Hooft (KMT) determinant term, using an explicit structure for the ground state in terms of quark antiquark condensates. The mass gap equations are solved self consistently and are used to compute the thermodynamic potential. We also derive the equation of state for strange quark matter in the presence of strong magnetic fields which could be relevant for proto-neutron stars.
Crystalline chiral condensates as a component of compact stars
Physical Review D, 2015
We investigate the influence of spatially inhomogeneous chiral symmetry-breaking condensates in a magnetic field background on the equation of state for compact stellar objects. After building a hybrid star composed of nuclear and quark matter using the Maxwell construction, we find, by solving the Tolman-Oppenheimer-Volkoff equations for stellar equilibrium, that our equation of state supports stars with masses around 2 M for values of the magnetic field that are in accordance with those inferred from magnetar data. The inclusion of a weak vector interaction term in the quark part allows to reach 2 solar masses for relatively small central magnetic fields, making this composition a viable possibility for describing the internal degrees of freedom of this class of astrophysical objects.
Self-Consistent Evolution of Magnetic Fields and Chiral Asymmetry in the Early Universe
Physical Review Letters, 2012
We show that the evolution of magnetic fields in a primordial plasma, filled with Standard Model particles, at temperatures T 10MeV is strongly affected by the quantum chiral anomaly -an effect that has been neglected previously. Although reactions equilibrating left and right-chiral electrons are in deep thermal equilibrium for T 80 TeV, an asymmetry between these particle develops in the presence of strong magnetic fields. This results in magnetic helicity transfer from shorter to longer scales. This also leads to an effective generation of lepton asymmetry that may survive in the plasma down to temperatures T ∼ 10 MeV, which may strongly affect many processes in the early Universe. Although we report our results for the Standard Model, they are likely to play an important role also in its extensions.
Quark-hadron phase transitions in the viscous early universe
Physical Review D, 2012
In the standard hot big bang theory, when the Universe was about 1-10 s old, the cosmological matter is conjectured to undergo quantum chromodynamics (QCD) phase transition(s) from quark matter to hadrons. In the present work, we study the cosmological quark-hadron phase transition in two different physical scenarios. First, by assuming that the phase transition would be described by an effective nucleation theory (prompt first-order phase transition), we analyze the evolution of the relevant cosmological parameters of the early universe (energy density , temperature T, Hubble parameter H, and the scale factor a) before, during, and after the phase transition. To study the cosmological dynamics and the time evolution, we use both analytical and numerical methods. The case where the Universe evolved through a mixed phase with a small initial supercooling and monotonically growing hadronic bubbles is also considered in detail. The numerical estimation of the cosmological parameters, a and H for instance, shows that the time evolution of the Universe varies from phase to phase. As the QCD era turns to be fairly accessible in the high-energy experiments and the lattice QCD simulations, the QCD equation of state is very well defined. In light of these QCD results, we develop a systematic study of the crossover quark-hadron phase transition, and an estimation for the time evolution of the Hubble parameter during the crossover.
Quantum chromodynamics phase transition in the early Universe and quark nuggets
Pramana, 2003
A first-order quark hadron phase transition in the early Universe may lead to the formation of quark nuggets. The baryon number distribution of these quark nuggets have been calculated and it has been found that there are sizeable number of quark nuggets in the stable sector. The nuggets can clump and form bigger objects in the mass range of 0 0003M ¬ to 0 12M ¬. It has been discussed that these bigger objects can be possible candidates for cold dark matter.
On the role of the strange quark and its mass in the chiral phase transition
2002
The evolution of the chiral condensate with the temperature is studied using SU(3) Chiral Perturbation Theory and the virial expansion. We observe a large decrease of the melting temperature of the non-strange condensate compared with the SU(2) case. Due to the larger mass of the strange quark we also find an slower temperature evolution of the strange condensate compared with the non-strange condensate.
Quark-Hadron Phase Transitions in Viscous Early Universe
Arxiv preprint arXiv:1108.5697, 2011
In the standard hot big bang theory, when the Universe was about 1-10 s old, the cosmological matter is conjectured to undergo quantum chromodynamics (QCD) phase transition(s) from quark matter to hadrons. In the present work, we study the cosmological quark-hadron phase transition in two different physical scenarios. First, by assuming that the phase transition would be described by an effective nucleation theory (prompt first-order phase transition), we analyze the evolution of the relevant cosmological parameters of the early universe (energy density , temperature T, Hubble parameter H, and the scale factor a) before, during, and after the phase transition. To study the cosmological dynamics and the time evolution, we use both analytical and numerical methods. The case where the Universe evolved through a mixed phase with a small initial supercooling and monotonically growing hadronic bubbles is also considered in detail. The numerical estimation of the cosmological parameters, a and H for instance, shows that the time evolution of the Universe varies from phase to phase. As the QCD era turns to be fairly accessible in the high-energy experiments and the lattice QCD simulations, the QCD equation of state is very well defined. In light of these QCD results, we develop a systematic study of the crossover quark-hadron phase transition, and an estimation for the time evolution of the Hubble parameter during the crossover.