Hubble parameter in QCD Universe for finite bulk viscosity

Tawfik, A.; Wahba, M.; Mansour, Hesham; Harkó, Tiberiu

doi:10.1002/andp.201000103

Cited by 26 publications

(26 citation statements)

References 30 publications

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“…At LHC energy, μ B is very small indicating a very small difference between particle and antiparticle. This situation likely fairly simulates the early Universe during the QCD era [72][73][74][76][77][78][79].…”

Section: Discussionmentioning

confidence: 99%

“…The vertical lines determine the co-moving time t and temperature T boundaries of the QCD era in early Universe, which can be assigned to the LHC energy [10,[35][36][37][38]. The function f (t) has been evaluated [74]. The resulting H (t) is depicted in Fig.…”

Section: Cosmological and Astrophysical Consequencesmentioning

confidence: 99%

“…Different solutions for the evolution equation of H have been worked out. For simplicity, we can assume that the deviation of H in viscous background matter from the one characterizing the ideal matter can perturbatively be given as [74] …”

Section: Cosmological and Astrophysical Consequencesmentioning

confidence: 99%

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Matter–Antimatter Asymmetry in Heavy-Ion Collisions

Tawfik¹

2011

Int J Theor Phys

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Implementing modified phase space and distribution function in grand-canonical ensemble and taking into account the experimental acceptance, the ratios of antiparticleto-particle over the whole range of energies are well reproduced by hadron resonance gas (HRG) model. We introduce a systematic study for antiparticle-to-particle ratios measured in various pp and AA collisions and find that the ratios of bosons and baryons get very close to unity indicating that the matter-antimatter asymmetry nearly vanishes at LHC energy. We predict that the LHC heavy-ion program will produce the same particle ratios as the pp program implying the dynamics and evolution of the system would not depend on the initial conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Cosmological and Astrophysical Consequencesmentioning

confidence: 99%

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Matter–Antimatter Asymmetry in Heavy-Ion Collisions

Tawfik¹

2011

Int J Theor Phys

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“…h seems to behave as an order parameter. The second part of this study is devoted to an extension of previous works [34][35][36][37][38][39][40], in which we have applied the equations of state deduced from recent lattice QCD simulations at almost physical masses and more accurate lattice configurations in order to study the cosmology of the early universe. With the use of these equations of state we can study the evolution equations of the main physical parameters of the cosmological models.…”

Section: Introductionmentioning

confidence: 99%

Quark-hadron phase transitions in the viscous early universe

Tawfik

Harkó

2012

Phys. Rev. D

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In the standard hot big bang theory, when the Universe was about 1 − 10 µs 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 ρ, 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 .

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“…(5). In general, the expansion rate of the Universe varies with the cosmological time [27][28][29][30][31][32][33][34]. It depends on the background matter/radiation and its dynamics [33].…”

Section: Introductionmentioning

confidence: 99%

Lorentz invariance violation and generalized uncertainty principle

Tawfik

Magdy

Ali

2016

Phys. Part. Nuclei Lett.

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There are several theoretical indications that the quantum gravity approaches may have predictions for a minimal measurable length, and a maximal observable momentum and throughout a generalization for Heisenberg uncertainty principle. The generalized uncertainty principle (GUP) is based on a momentum-dependent modification in the standard dispersion relation which is conjectured to violate the principle of Lorentz invariance. From the resulting Hamiltonian, the velocity and time of flight of relativistic distant particles at Planck energy can be derived. A first comparison is made with recent observations for Hubble parameter in redshift-dependence in early-type galaxies. We find that LIV has two types of contributions to the time of flight delay ∆t comparable with that observations. Although the wrong OPERA measurement on faster-than-light muon neutrino anomaly, ∆t, and the relative change in the speed of muon neutrino ∆v in dependence on redshift z turn to be wrong, we utilize its main features to estimate ∆v. Accordingly, the results could not be interpreted as LIV. A third comparison is made with the ultra high-energy cosmic rays (UHECR). It is found that an essential ingredient of the approach combining string theory, loop quantum gravity, black hole physics and doubly spacial relativity and the one assuming a perturbative departure from exact Lorentz invariance. Fixing the sensitivity factor and its energy dependence are essential inputs for a reliable confronting of our calculations to UHECR. The sensitivity factor is related to the special time of flight delay and the time structure of the signal. Furthermore, the upper and lower bounds to the parameter, α that characterizes the generalized uncertainly principle, have to be fixed in related physical systems such as the gamma rays bursts.

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Hubble parameter in QCD Universe for finite bulk viscosity

Cited by 26 publications

References 30 publications

Matter–Antimatter Asymmetry in Heavy-Ion Collisions

Matter–Antimatter Asymmetry in Heavy-Ion Collisions

Quark-hadron phase transitions in the viscous early universe

Lorentz invariance violation and generalized uncertainty principle

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