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Editorial

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3 pages, 170 KiB

Open AccessEditorial

Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions

by Roman Pasechnik and Michal Šumbera

Universe 2022, 8(10), 545; https://doi.org/10.3390/universe8100545 - 19 Oct 2022

Viewed by 949

Abstract

The basic aim of this Special Issue was to reflect upon the modern status of research on strong interactions and their implications in Cosmology [...] Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

Research

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40 pages, 519 KiB

Open AccessArticle

Dark Side of Weyl Gravity

by Petr Jizba, Lesław Rachwał, Stefano G. Giaccari and Jaroslav Kňap

Universe 2020, 6(8), 123; https://doi.org/10.3390/universe6080123 - 12 Aug 2020

Cited by 6 | Viewed by 2616

Abstract

We address the issue of a dynamical breakdown of scale invariance in quantum Weyl gravity together with related cosmological implications. In the first part, we build on our previous work [Phys. Rev. D2020, 101, 044050], where we found a [...] Read more.

We address the issue of a dynamical breakdown of scale invariance in quantum Weyl gravity together with related cosmological implications. In the first part, we build on our previous work [Phys. Rev. D2020, 101, 044050], where we found a non-trivial renormalization group fixed point in the infrared sector of quantum Weyl gravity. Here, we prove that the ensuing non-Gaussian IR fixed point is renormalization scheme independent. This confirms the feasibility of the analog of asymptotic safety scenario for quantum Weyl gravity in the IR. Some features, including non-analyticity and a lack of autonomy, of the system of

β

-functions near a turning point of the renormalization group at intermediate energies are also described. We further discuss an extension of the renormalization group analysis to the two-loop level. In particular, we show universal properties of the system of

β

-functions related to three couplings associated with

C^{2}

(Weyl square),

G

(Gauss–Bonnet), and

R^{2}

(Ricci curvature square) terms. Finally, we discuss various technical and conceptual issues associated with the conformal (trace) anomaly and propose possible remedies. In the second part, we analyze physics in the broken phase. In particular, we show that, in the low-energy sector of the broken phase, the theory looks like Starobinsky

f (R)

gravity with a gravi-cosmological constant that has a negative sign in comparison to the usual matter-induced cosmological constant. We discuss implications for cosmic inflation and highlight a non-trivial relation between Starobinsky’s parameter and the gravi-cosmological constant. Salient issues, including possible UV completions of quantum Weyl gravity and the role of the trace anomaly matching, are also discussed. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

7 pages, 256 KiB

Open AccessArticle

Parton Distribution Functions and Tensorgluons

by Roland Kirschner and George Savvidy

Universe 2020, 6(7), 88; https://doi.org/10.3390/universe6070088 - 29 Jun 2020

Cited by 1 | Viewed by 1892

Abstract

We derive the regularised evolution equations for the parton distribution functions that include tensorgluons. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

10 pages, 313 KiB

Open AccessArticle

Invisible QCD as Dark Energy

by Andrea Addazi, Stephon Alexander and Antonino Marcianò

Universe 2020, 6(6), 75; https://doi.org/10.3390/universe6060075 - 31 May 2020

Cited by 3 | Viewed by 1680

Abstract

We account for the late time acceleration of the Universe by extending the Quantum Chromodynamics (QCD) color to a

S U (3)

invisible sector (IQCD). If the Invisible Chiral symmetry is broken in the early universe, a condensate of dark pions [...] Read more.

We account for the late time acceleration of the Universe by extending the Quantum Chromodynamics (QCD) color to a

S U (3)

invisible sector (IQCD). If the Invisible Chiral symmetry is broken in the early universe, a condensate of dark pions (dpions) and dark gluons (dgluons) forms. The condensate naturally forms due to strong dynamics similar to the Nambu–Jona-Lasinio mechanism. As the Universe evolves from early times to present times the interaction energy between the dgluon and dpion condensate dominates with a negative pressure equation of state and causes late time acceleration. We conclude with a stability analysis of the coupled perturbations of the dark pions and dark gluons. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

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15 pages, 419 KiB

Open AccessArticle

Evolution of Quasiperiodic Structures in a Non-Ideal Hydrodynamic Description of Phase Transitions

by D. N. Voskresensky

Universe 2020, 6(3), 42; https://doi.org/10.3390/universe6030042 - 07 Mar 2020

Cited by 2 | Viewed by 2004

Abstract

Various phase transitions could have taken place in the early universe, and may occur in the course of heavy-ion collisions and supernova explosions, in proto-neutron stars, in cold compact stars, and in the condensed matter at terrestrial conditions. Most generally, the dynamics of [...] Read more.

Various phase transitions could have taken place in the early universe, and may occur in the course of heavy-ion collisions and supernova explosions, in proto-neutron stars, in cold compact stars, and in the condensed matter at terrestrial conditions. Most generally, the dynamics of the density and temperature at first- and second-order phase transitions can be described with the help of the equations of non-ideal hydrodynamics. In the given work, some novel solutions are found describing the evolution of quasiperiodic structures that are formed in the course of the phase transitions. Although this consideration is very general, particular examples of quark-hadron and nuclear liquid-gas first-order phase transitions to the uniform

k_{0} = 0

state and of a pion-condensate second-order phase transition to a non-uniform

k_{0} \neq 0

state in dense baryon matter are considered. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

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Review

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77 pages, 2592 KiB

Open AccessReview

Cosmology from Strong Interactions

by Andrea Addazi, Torbjörn Lundberg, Antonino Marcianò, Roman Pasechnik and Michal Šumbera

Universe 2022, 8(9), 451; https://doi.org/10.3390/universe8090451 - 29 Aug 2022

Cited by 6 | Viewed by 2047

Abstract

The wealth of theoretical and phenomenological information about Quantum Chromodynamics at short and long distances collected so far in major collider measurements has profound implications in cosmology. We provide a brief discussion on the major implications of the strongly coupled dynamics of quarks [...] Read more.

The wealth of theoretical and phenomenological information about Quantum Chromodynamics at short and long distances collected so far in major collider measurements has profound implications in cosmology. We provide a brief discussion on the major implications of the strongly coupled dynamics of quarks and gluons as well as on effects due to their collective motion on the physics of the early universe and in astrophysics. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

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30 pages, 1286 KiB

Open AccessReview

New Physics of Strong Interaction and Dark Universe

by Vitaly Beylin, Maxim Khlopov, Vladimir Kuksa and Nikolay Volchanskiy

Universe 2020, 6(11), 196; https://doi.org/10.3390/universe6110196 - 26 Oct 2020

Cited by 28 | Viewed by 2403

Abstract

The history of dark universe physics can be traced from processes in the very early universe to the modern dominance of dark matter and energy. Here, we review the possible nontrivial role of strong interactions in cosmological effects of new physics. In the [...] Read more.

The history of dark universe physics can be traced from processes in the very early universe to the modern dominance of dark matter and energy. Here, we review the possible nontrivial role of strong interactions in cosmological effects of new physics. In the case of ordinary QCD interaction, the existence of new stable colored particles such as new stable quarks leads to new exotic forms of matter, some of which can be candidates for dark matter. New QCD-like strong interactions lead to new stable composite candidates bound by QCD-like confinement. We put special emphasis on the effects of interaction between new stable hadrons and ordinary matter, formation of anomalous forms of cosmic rays and exotic forms of matter, like stable fractionally charged particles. The possible correlation of these effects with high energy neutrino and cosmic ray signatures opens the way to study new physics of strong interactions by its indirect multi-messenger astrophysical probes. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

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13 pages, 910 KiB

Open AccessReview

An SU(2) Gauge Principle for the Cosmic Microwave Background: Perspectives on the Dark Sector of the Cosmological Model

by Ralf Hofmann

Universe 2020, 6(9), 135; https://doi.org/10.3390/universe6090135 - 24 Aug 2020

Cited by 3 | Viewed by 2875

Abstract

We review consequences for the radiation and dark sectors of the cosmological model arising from the postulate that the Cosmic Microwave Background (CMB) is governed by an SU(2) rather than a U(1) gauge principle. We also speculate on the possibility of actively assisted [...] Read more.

We review consequences for the radiation and dark sectors of the cosmological model arising from the postulate that the Cosmic Microwave Background (CMB) is governed by an SU(2) rather than a U(1) gauge principle. We also speculate on the possibility of actively assisted structure formation due to the de-percolation of lump-like configurations of condensed ultralight axions with a Peccei–Quinn scale comparable to the Planck mass. The chiral-anomaly induced potential of the axion condensate receives contributions from SU(2)/SU(3) Yang–Mills factors of hierarchically separated scales which act in a screened (reduced) way in confining phases. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

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21 pages, 513 KiB

Open AccessReview

The Equation of State of Nuclear Matter: From Finite Nuclei to Neutron Stars

by G. Fiorella Burgio and Isaac Vidaña

Universe 2020, 6(8), 119; https://doi.org/10.3390/universe6080119 - 10 Aug 2020

Cited by 25 | Viewed by 3309

Abstract

Background. We investigate possible correlations between neutron star observables and properties of atomic nuclei. In particular, we explore how the tidal deformability of a 1.4 solar mass neutron star,

M_{1.4}

, and the neutron-skin thickness of

^{48}

Ca and

^{208}

Pb are [...] Read more.

Background. We investigate possible correlations between neutron star observables and properties of atomic nuclei. In particular, we explore how the tidal deformability of a 1.4 solar mass neutron star,

M_{1.4}

, and the neutron-skin thickness of

^{48}

Ca and

^{208}

Pb are related to the stellar radius and the stiffness of the symmetry energy. Methods. We examine a large set of nuclear equations of state based on phenomenological models (Skyrme, NLWM, DDM) and ab initio theoretical methods (BBG, Dirac–Brueckner, Variational, Quantum Monte Carlo). Results: We find strong correlations between tidal deformability and NS radius, whereas a weaker correlation does exist with the stiffness of the symmetry energy. Regarding the neutron-skin thickness, weak correlations appear both with the stiffness of the symmetry energy, and the radius of a

M_{1.4}

. Our results show that whereas the considered EoS are compatible with the largest masses observed up to now, only five microscopic models and four Skyrme forces are simultaneously compatible with the present constraints on L and the PREX experimental data on the

^{208}

Pb neutron-skin thickness. We find that all the NLWM and DDM models and the majority of the Skyrme forces are excluded by these two experimental constraints, and that the analysis of the data collected by the NICER mission excludes most of the NLWM considered. Conclusion. The tidal deformability of a

M_{1.4}

and the neutron-skin thickness of atomic nuclei show some degree of correlation with nuclear and astrophysical observables, which however depends on the ensemble of adopted EoS. Full article

(This article belongs to the Special Issue Shedding Light to the Dark Sides of the Universe: Cosmology from Strong Interactions)

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