scholarly journals QCD phase transition with a power law chameleon scalar field in the bulk

2014 ◽  
Vol 29 (07) ◽  
pp. 1450033 ◽  
Author(s):  
Tayeb Golanbari ◽  
Abolhassan Mohammadi ◽  
Khaled Saaidi
Keyword(s):  
Phase Transition ◽  
Scalar Field ◽  
Evolution Equations ◽  
Friedmann Equation ◽  
Big Bang ◽  
Conservation Equation ◽  
Hadron Phase ◽  
Energy Conservation Equation ◽  
First Order Phase Transition ◽  
First Order Phase

In this paper, a braneworld model with a perfect fluid on brane and a scalar field on bulk has been used to study quark–hadron phase transition. The bulk scalar field has an interaction with brane matter. This interaction comes into nonconservation relation which describes an energy transfer between bulk and brane. Since quark–hadron transition truly depends on the form of evolution equations, modification of energy conservation equation and Friedmann equation gives rise to some interesting results about the time of transition. The evolution of physical quantities relevant to the quantitative of early times namely energy density ρ, temperature T and scale factor a have been considered utilizing two formalism, crossover formalism and first-order phase transition formalism. The results show that the quark–hadron phase transition occurred about a nanosecond after big bang and the general behavior temperature is similar in both of two formalism.

SOME THOUGHTS ON THE COSMOLOGICAL QCD PHASE TRANSITION

2008 ◽  
Vol 23 (30) ◽  
pp. 4757-4777
Author(s):  
W-Y. P. HWANG
Keyword(s):  
Phase Transition ◽  
Scalar Field ◽  
Order Phase Transition ◽  
Domain Walls ◽  
Wall Structure ◽  
Complex Scalar ◽  
Qcd Phase Transition ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

The cosmological QCD phase transitions may have taken place between 10-5 s and 10-4 s in the early universe offers us one of the most intriguing and fascinating questions in cosmology. In bag models, the phase transition is described by the first-order phase transition and the role played by the latent "heat" or energy released in the transition is highly nontrivial and is being classified as the first-order phase transition. In this presentation, we assume, first of all, that the cosmological QCD phase transition, which happened at a time between 10-5 s and 10-4 s or at the temperature of about 150 MeV and accounts for confinement of quarks and gluons to within hadrons, would be of first-order. Of course, we may assume that the cosmological QCD phase transition may not be of the first-order. To get the essence out of the first-order scenario, it is sufficient to approximate the true QCD vacuum as one of possibly degenerate vacua and when necessary we try to model it effectively via a complex scalar field with spontaneous symmetry breaking. On the other hand, we may use a real scalar field in describing the non-first-order QCD phase transition. In the first-order QCD phase transition, we could examine how and when "pasted" or "patched" domain walls are formed, how long such walls evolve in the long run, and we believe that the significant portion of dark matter could be accounted for in terms of such domain-wall structure and its remnants. Of course, the cosmological QCD phase transition happened in the way such that the false vacua associated with baryons and many other color-singlet objects did not disappear (that is, using the bag-model language, there are bags of radius 1.0 fermi for the baryons) — but the amount of the energy remained in the false vacua is negligible by comparison. The latent energy released due to the conversion of the false vacua to the true vacua, in the form of "pasted" or "patched" domain walls in the short run and their numerous evolved objects, should make the concept of the "radiation-dominated" epoch, or of the "matter-dominated" epoch to be reexamined.

NUCLEATION OF VACUUM BUBBLES OF A SELF-GRAVITATING SCALAR FIELD

2012 ◽  
Vol 12 ◽  
pp. 340-349 ◽  
Author(s):  
CHUL H. LEE ◽  
WONWOO LEE
Keyword(s):  
Phase Transition ◽  
Scalar Field ◽  
Order Phase Transition ◽  
Nonminimal Coupling ◽  
False Vacuum ◽  
First Order ◽  
First Order Phase Transition ◽  
True Vacuum ◽  
Self Gravity ◽  
First Order Phase

The case of a self-gravitating scalar field under-going the first-order phase transition is studied. Particularly the effects of self gravity on the nucleation of vacuum bubbles is investigated. We also investigate what modifications are induced by the introduction of nonminimal coupling of the scalar field. The possibility of nucleation of false vacuum bubbles within the true vacuum background in the case of a nonminimally coupled scalar field is discussed.

Dynamical Evolution of the Universe in the Quark-Hadron Phase Transition and Nugget Formation

2005 ◽  
Vol 201 ◽  
pp. 461-462
Author(s):  
Ashok. Goyal ◽  
Deepak. Chandra
Keyword(s):  
Phase Transition ◽  
Early Universe ◽  
Dynamical Evolution ◽  
First Order ◽  
Evolution Of The Universe ◽  
Hadron Phase ◽  
First Order Phase Transition ◽  
Nugget Formation ◽  
First Order Phase ◽  
The Universe

We study the dynamics of first-order phase transition in the early Universe when it was 10 −50μs old with quarks and gluons condensing into hadrons. We look at the evolution of the Universe in small as well as large super cooling scenario.

scholarly journals Gravitational wave signals of dark matter freeze-out

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Danny Marfatia ◽  
Po-Yan Tseng
Keyword(s):  
Phase Transition ◽  
Dark Matter ◽  
Gravitational Waves ◽  
Order Phase Transition ◽  
First Order ◽  
Stochastic Background ◽  
First Order Phase Transition ◽  
Relic Abundance ◽  
First Order Phase ◽  
Freeze Out

Abstract We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the measured dark matter relic abundance via (1) bubble filtering, and (2) inflation and reheating, and show that gravitational waves from these mechanisms are detectable at future interferometers.

scholarly journals Dark Matter production from relativistic bubble walls

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Aleksandr Azatov ◽  
Miguel Vanvlasselaer ◽  
Wen Yin
Keyword(s):  
Phase Transition ◽  
Dark Matter ◽  
Electroweak Phase Transition ◽  
First Order ◽  
Matter Production ◽  
First Order Phase Transition ◽  
Relic Abundance ◽  
Higgs Portal ◽  
First Order Phase ◽  
Gravitational Background

Abstract In this paper we present a novel mechanism for producing the observed Dark Matter (DM) relic abundance during the First Order Phase Transition (FOPT) in the early universe. We show that the bubble expansion with ultra-relativistic velocities can lead to the abundance of DM particles with masses much larger than the scale of the transition. We study this non-thermal production mechanism in the context of a generic phase transition and the electroweak phase transition. The application of the mechanism to the Higgs portal DM as well as the signal in the Stochastic Gravitational Background are discussed.

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