scholarly journals Testing a Dilaton Gravity Model Using Nucleosynthesis

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
S. Boran ◽  
E. O. Kahya
Keyword(s):  
Steady State ◽  
Gravity Model ◽  
Big Bang ◽  
Universe Model ◽  
Light Elements ◽  
Dilaton Gravity ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Higher Dimensional ◽  
State Universe

Big bang nucleosynthesis (BBN) offers one of the most strict evidences for theΛ-CDM cosmology at present, as well as the cosmic microwave background (CMB) radiation. In this work, our main aim is to present the outcomes of our calculations related to primordial abundances of light elements, in the context of higher dimensional steady-state universe model in the dilaton gravity. Our results show that abundances of light elements (primordial D,3He,4He, T, and7Li) are significantly different for some cases, and a comparison is given between a particular dilaton gravity model andΛ-CDM in the light of the astrophysical observations.

scholarly journals A new tension in the cosmological model from primordial deuterium?

2021 ◽  
Vol 502 (2) ◽  
pp. 2474-2481
Author(s):  
Cyril Pitrou ◽  
Alain Coc ◽  
Jean-Philippe Uzan ◽  
Elisabeth Vangioni
Keyword(s):  
Big Bang ◽  
Reaction Cross ◽  
Light Elements ◽  
Neutron Lifetime ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Baryonic Density ◽  
The Status ◽  
Big Bang Model ◽  
The Big Bang

ABSTRACT Recent measurements of the D(p,γ)3He nuclear reaction cross-section and of the neutron lifetime, along with the reevaluation of the cosmological baryon abundance from cosmic microwave background (CMB) analysis, call for an update of abundance predictions for light elements produced during the big-bang nucleosynthesis (BBN). While considered as a pillar of the hot big-bang model in its early days, BBN constraining power mostly rests on deuterium abundance. We point out a new ≃1.8σ tension on the baryonic density, or equivalently on the D/H abundance, between the value inferred on one hand from the analysis of the primordial abundances of light elements and, on the other hand, from the combination of CMB and baryonic oscillation data. This draws the attention on this sector of the theory and gives us the opportunity to reevaluate the status of BBN in the context of precision cosmology. Finally, this paper presents an upgrade of the BBN code primat.

scholarly journals Time Direction of Information Propagation and Cosmology

1972 ◽  
Vol 25 (2) ◽  
pp. 207 ◽  
Author(s):  
DT Pegg
Keyword(s):  
Steady State ◽  
Ad Hoc ◽  
Big Bang ◽  
Information Propagation ◽  
The Past ◽  
The Future ◽  
Consistent Solution ◽  
Electrodynamic Theory ◽  
The Universe ◽  
State Universe

In conventional electrodynamic theory, the advanced potential solution of Maxwell's equations is discarded on the ad hoc basis that information can be received from the past only and not from the future. This difficulty is overcome by the Wheeler?Feynman absorber theory, but unfortunately the existence of a completely retarded solution in this theory requires a steady-state universe. In the present paper conventional electrodynamics is used to obtain a condition which, if satisfied, allows information to be received from the past only, and ensures that the retarded potential is the only consistent solution. The condition is that a function Ua of the future structure of the universe is infinite, while the corresponding function Ur of the past structure is finite. Of the currently acceptable cosmological models, only the steady-state, the open big-bang, and the Eddington-Lema�tre models satisfy this condition. In these models there is no need for an ad hoc reason for the preclusion of advanced potentials.

scholarly journals Impact of neutrino properties and dark matter on the primordial Lithium production

2019 ◽  
Vol 28 (08) ◽  
pp. 1950065 ◽  
Author(s):  
Tahani R. Makki ◽  
Mounib F. El Eid ◽  
Grant J. Mathews
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Nuclear Physics ◽  
Big Bang ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Chemical Potentials ◽  
The Creation ◽  
The Universe

The light elements and their isotopes were produced during standard big bang nucleosynthesis (SBBN) during the first minutes after the creation of the universe. Comparing the calculated abundances of these light species with observed abundances, it appears that all species match very well except for lithium (7Li) which is overproduced by the SBBN. This discrepancy is rather challenging for several reasons to be considered on astrophysical and on nuclear physics ground, or by invoking nonstandard assumptions which are the focus of this paper. In particular, we consider a variation of the chemical potentials of the neutrinos and their temperature. In addition, we investigated the effect of dark matter on 7Li production. We argue that including nonstandard assumptions can lead to a significant reduction of the 7Li abundance compared to that of SBBN. This aspect of lithium production in the early universe may help to resolve the outstanding cosmological lithium problem.

Steady-State theory and the cosmological controversy

2019 ◽  
pp. 161-205
Author(s):  
Helge Kragh
Keyword(s):  
Steady State ◽  
Big Bang ◽  
State Theory ◽  
Steady State Model ◽  
Big Bang Theory ◽  
Big Bang Model ◽  
Fred Hoyle ◽  
The Big Bang ◽  
The Universe ◽  
State Universe

The presently accepted big-bang model of the universe emerged during the period 1930-1970, following a road that was anything but smooth. By 1950 the essential features of the big-bang theory were established by George Gamow and his collaborators, and yet the theory failed to win recognition. A major reason was that the big-bang picture of the evolving universe was challenged by the radically different picture of a steady-state universe favoured by Fred Hoyle and others. By the late 1950s there was no convincing reason to adopt one theory over the other. Out of the epic controversy between the two incompatible world models arose our modern view of the universe. Although the classical steady-state model was abandoned in the mid-1960s, attempts to modify it can be followed up to the present.

scholarly journals Unlocking the synergy between CMB spectral distortions and anisotropies

2021 ◽  
Vol 2021 (12) ◽  
pp. 050
Author(s):  
Hao Fu ◽  
Matteo Lucca ◽  
Silvia Galli ◽  
Elia S. Battistelli ◽  
Deanna C. Hooper ◽  
...  
Keyword(s):  
Spectral Index ◽  
Big Bang ◽  
Noise Levels ◽  
Microwave Background ◽  
Big Bang Nucleosynthesis ◽  
Scalar Spectral Index ◽  
New Information ◽  
Wide Range ◽  
Inflationary Parameters ◽  
Better Than

Abstract Measurements of the cosmic microwave background (CMB) spectral distortions (SDs) will open a new window on the very early universe, providing new information complementary to that gathered from CMB temperature and polarization anisotropies. In this paper, we study their synergy as a function of the characteristics of the considered experiments. In particular, we examine a wide range of sensitivities for possible SD measurements, spanning from FIRAS up to noise levels 1000 times better than PIXIE, and study their constraining power when combined with current or future CMB anisotropy experiments such as Planck or LiteBIRD plus CMB-S4. We consider a number of different cosmological models such as the ΛCDM, as well as its extensions with the running of the scalar spectral index, the decay or the annihilation of dark matter (DM) particles. While upcoming CMB anisotropy experiments will be able to decrease the uncertainties on inflationary parameters such as As and ns by about a factor 2 in the ΛCDM case, we find that an SD experiment 100 times more sensitive than PIXIE (comparable to the proposed Super-PIXIE satellite) could potentially further contribute to constrain these parameters. This is even more significant in the case of the running of the scalar spectral index. Furthermore, as expected, constraints on DM particles decaying at redshifts probed by SDs will improve by orders of magnitude even with an experiment 10 times worse than PIXIE as compared to CMB anisotropies or Big Bang Nucleosynthesis bounds. On the contrary, DM annihilation constraints will not significantly improve over CMB anisotropy measurements. Finally, we forecast the constraints obtainable with sensitivities achievable either from the ground or from a balloon.

The Battle for the Cosmos!

2019 ◽  
pp. 84-92
Author(s):  
Nicholas Mee
Keyword(s):  
Steady State ◽  
Cosmic Microwave Background ◽  
Big Bang ◽  
State Theory ◽  
Microwave Background ◽  
George Gamow ◽  
Big Bang Theory ◽  
Fred Hoyle ◽  
The Big Bang ◽  
The Universe

We now know the universe began with the Big Bang 13.8 billion years ago, but for several years debate raged between the supporters of the Big Bang theory led by George Gamow and supporters of the Steady State theory led by Fred Hoyle. Hoyle showed that the elements were synthesized in the stars, not in the Big Bang as Gamow believed. But Gamow’s colleagues Alpher and Herman predicted the existence of the cosmic microwave background (CMB) created immediately after the Big Bang. The CMB was discovered by Penzias and Wilson and this provided the crucial evidence that the Big Bang theory is correct. The CMB has since been studied in detail by a series of space probes.

scholarly journals Big Bang Nucleosynthesis and Lepton Number Asymmetry in the Universe

1999 ◽  
Vol 183 ◽  
pp. 312-312
Author(s):  
K. Kohri ◽  
M. Kawasaki ◽  
Katsuhiko Sato
Keyword(s):  
Chemical Potential ◽  
High Redshift ◽  
Big Bang ◽  
Electron Neutrino ◽  
Light Elements ◽  
Big Bang Nucleosynthesis ◽  
Lepton Asymmetry ◽  
Stringent Constraint ◽  
Likelihood Analysis ◽  
The Universe

Recently it has been reported that there may be a discrepancy between big bang nucleosynthesis theory and observations (BBN crisis) (Hata et al., 1995). One way to solve the discrepancy might be to adopt some modifications of standard physics used in SBBN (Kawasaki et al, 1997). We show that BBN predictions agree with the primordial abundances of light elements, 4He, D, 3He and 7Li inferred from the observational data if the electron neutrino has a net chemical potential ξve due to lepton asymmetry (Kohri et al., 1997). We study BBN with the effects of the neutrino degeneracy in details using Monte Carlo simulation and make a likelihood analysis using the most recent data. We estimate that (95% C.L.) and (95% C.L.) adopting the presolar Deuterium abundance as the primordial values. If we adopted the low D abundance which is obtained by the observation of the high redshift QSO absorption systems, (95% C.L.) and The estimated chemical potential of ve is about 10−5 eV which is much smaller than experiments can detect (≃ 1 eV). In other words, BBN gives the most stringent constraint on the chemical potential of ve.

Sign in / Sign up

Export Citation Format

Share Document