scholarly journals Limits on brane-world and particle dark radiation from big bang nucleosynthesis and the CMB

2017 ◽  
Vol 26 (08) ◽  
pp. 1741007 ◽  
Author(s):  
N. Sasankan ◽  
Mayukh R. Gangopadhyay ◽  
G. J. Mathews ◽  
M. Kusakabe
Keyword(s):  
Energy Density ◽  
Power Spectrum ◽  
Light Element ◽  
Reaction Rates ◽  
Big Bang ◽  
Brane World ◽  
Expansion Rate ◽  
Big Bang Nucleosynthesis ◽  
Dark Radiation ◽  
Element Abundances

The term dark radiation is used both to describe a noninteracting neutrino species and as a correction to the Friedmann Equation in the simplest five-dimensional (5D) RS-II brane-world cosmology. In this paper, we consider the constraints on both the meanings of dark radiation-based upon the newest results for light-element nuclear reaction rates, observed light-element abundances and the power spectrum of the Cosmic Microwave Background (CMB). Adding dark radiation during big bang nucleosynthesis (BBN) alters the Friedmann expansion rate causing the nuclear reactions to freeze out at a different temperature. This changes the final light element abundances at the end of BBN. Its influence on the CMB is to change the effective expansion rate at the surface of the last scattering. We find that the BBN constraint reduces the allowed range for both types of dark radiation at 10[Formula: see text]Mev to between [Formula: see text] and [Formula: see text] of the total background energy density at 10[Formula: see text]Mev. Combining this result with fits to the CMB power spectrum, produces different results for particle versus brane-world dark radiation. In the brane-world, the range decreases from [Formula: see text] to [Formula: see text]. Thus, we find that the ratio of dark radiation to the background total relativistic mass energy density [Formula: see text] is consistent with zero although there remains a very slight preference for a positive (rather than negative) contribution.

scholarly journals Primordial Nucleosynthesis: Constraints on the Birth of the Universe

2018 ◽  
Vol 184 ◽  
pp. 01011
Author(s):  
Grant Mathews ◽  
Motohiko Kusakabe ◽  
Mayukh Gangopadhyay ◽  
Toshitaka Kajino ◽  
Nishanth Sasankan
Keyword(s):  
Cosmic Microwave Background ◽  
Light Element ◽  
Higher Dimensions ◽  
Big Bang ◽  
Energy Scale ◽  
Brane World ◽  
Microwave Background ◽  
Dark Radiation ◽  
Element Abundances ◽  
The Universe

We review the basic elements of big bang nucleosythesis (BBN) and how a comparison of predicted light-element abundances with observations constrains physics of the radiation-dominated epoch. We then summarize some applications of BBN and the cosmic microwave background (CMB) to constrain the first moments of the birth of the universe. In particular, we discuss how the existence of higher dimensions impacts the cosmic expansion through the projection of curvature from the higher dimension in the "dark radiation" term. We summarize current constraints from BBN and the CMB on this brane-world dark radiation term. At the same time, the existence of extra dimensions during the earlier inflation impacts the tensor to scalar ratio and the running spectral index as measured in the CMB. We summarize how the constraints on inflation shift when embedded in higher dimensions. Finally, one expects that the universe was born out of a complicated multiverse landscape near the Planck time. In these moments the energy scale of superstrings was obtainable during the early moments of chaotic inflation. We summarize the quest for cosmological evidence of the birth of space-time out of the string theory landscape. We will explore the possibility that a superstring excitations may have made itself known via a coupling to the field of inflation. This may have left an imprint of "dips" in the power spectrum of temperature fluctuations in the cosmic microwave background. The identification of this particle as a superstring is possible because there may be evidence for different oscillator states of the same superstring that appear on different scales on the sky. It will be shown that from this imprint one can deduce the mass, number of oscillations, and coupling constant for the superstring. Although the evidence is marginal, this may constitute the first observation of a superstring in Nature.

Big Bang nucleosynthesis, microwave anisotropy, and the light element abundances

2005 ◽  
Vol 752 ◽  
pp. 522-531 ◽  
Author(s):  
A. Coc ◽  
C. Angulo ◽  
E. Vangioni-Flam ◽  
P. Descouvemont ◽  
A. Adahchour
Keyword(s):  
Light Element ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Element Abundances

scholarly journals Progress on the BL2 beam measurement of the neutron lifetime

2019 ◽  
Vol 219 ◽  
pp. 03002 ◽  
Author(s):  
Shannon F. Hoogerheide ◽  
Jimmy Caylor ◽  
Evan R. Adamek ◽  
Eamon S. Anderson ◽  
Ripan Biswas ◽  
...  
Keyword(s):  
Light Element ◽  
Big Bang ◽  
Neutron Lifetime ◽  
Big Bang Nucleosynthesis ◽  
Element Abundances ◽  
Cold Neutron Beam ◽  
The Standard Model ◽  
Systematic Effects ◽  
Mixing Matrix ◽  
Beam Technique

A precise value of the neutron lifetime is important in several areas of physics, including determinations of the quark-mixing matrix element |Vud|, related tests of the Standard Model, and predictions of light element abundances in Big Bang Nucleosynthesis models. We report the progress on a new measurement of the neutron lifetime utilizing the cold neutron beam technique. Several experimental improvements in both neutron and proton counting that have been developed over the last decade are presented. This new effort should yield a final uncertainty on the lifetime of 1 s with an improved understanding of the systematic effects.

Signature of Long-lived Relic Particles on Primordial Light Element Abundances in Big Bang Nucleosynthesis

2010 ◽  
Author(s):  
Motohiko Kusakabe ◽  
Toshitaka Kajino ◽  
Takashi Yoshida ◽  
Grant J. Mathews ◽  
Isao Tanihara ◽  
...  
Keyword(s):  
Light Element ◽  
Big Bang ◽  
Big Bang Nucleosynthesis ◽  
Element Abundances

POSSIBILITY OF A SIGNATURE OF THE RADIATIVE DECAY OF RELIC PARTICLES ON LIGHT ELEMENT ABUNDANCES

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2019-2026
Author(s):  
MOTOHIKO KUSAKABE ◽  
TOSHITAKA KAJINO ◽  
GRANT J. MATHEWS
Keyword(s):  
Radiative Decay ◽  
Light Element ◽  
Big Bang ◽  
Decay Process ◽  
Big Bang Nucleosynthesis ◽  
Element Abundances ◽  
Unstable Particles ◽  
Halo Stars ◽  
Primordial Abundance ◽  
Isotopic Abundances

Recent spectroscopic observations of metal poor stars have indicated that both 7 Li and 6 Li have abundance plateaus as a function of the metallicity. Abundances of 7 Li are about a factor three lower than the primordial abundance predicted by standard big-bang nucleosynthesis (SBBN), and 6 Li abundances are ~ 1/20 of 7 Li , whereas SBBN predicts negligible amounts of 6 Li compared to the detected level. These discrepancies suggest that 6 Li has another cosmological or Galactic origin. Furthermore, it appear that 7 Li (and also 6 Li ) has been depleted from its primordial abundance by some post-BBN processes. We study the possibility that the radiative decay of long-lived particles has affected the cosmological lithium abundances in reality. We calculate the non-thermal nucleosynthesis associated with the radiative decay, and explore the allowed region of the parameters specifying the properties of long-lived particles. We also impose constraints from observations of the CMB energy spectrum. It is found that non-thermal nucleosynthesis could produces 6 Li at the level detected in metal poor halo stars (MPHSs), when the lifetime of the unstable particles is of the order ~ 108 − 1012 s depending on their initial abundance. We conclude that a combination of two different processes could explain the lithium isotopic abundances in MPHSs. First, a non-thermal cosmological nucleosynthesis associated with the radiative decay of unstable particles; and second, about the same degree of stellar depletion of both primordial lithium isotopic abundances. If MPHSs experience 6 Li depletion of factor much greater than ~ 3, the simple radiative decay process can not be the cause of large 6 Li abundances in MPHSs.

BIG BANG NUCLEOSYNTHESIS: AN UPDATE

1996 ◽  
Vol 11 (03) ◽  
pp. 409-428 ◽  
Author(s):  
KEITH A. OLIVE ◽  
SEAN T. SCULLY
Keyword(s):  
Standard Model ◽  
Light Element ◽  
Big Bang ◽  
Current Status ◽  
Beyond The Standard Model ◽  
Effective Number ◽  
Big Bang Nucleosynthesis ◽  
Element Abundances ◽  
The Standard Model

The current status of big bang nucleosynthesis is reviewed with an emphasis on the comparison between the observational determination of the light element abundances of D , 3 He , 4 He and 7 Li and the predictions from theory. In particular, we present new analyses for 4 He and 7 Li . Implications for physics beyond the standard model are also discussed. In addition, limits on the effective number of neutrino flavors are updated.

scholarly journals Big Bang nucleosynthesis with long-lived strongly interacting relic particles

2009 ◽  
Vol 5 (S268) ◽  
pp. 33-38
Author(s):  
Motohiko Kusakabe ◽  
Toshitaka Kajino ◽  
Takashi Yoshida ◽  
Grant J. Mathews
Keyword(s):  
Beta Decay ◽  
Bound States ◽  
Nuclear Reactions ◽  
Interaction Strength ◽  
Light Element ◽  
Big Bang ◽  
Heavy Elements ◽  
Big Bang Nucleosynthesis ◽  
Element Abundances ◽  
Strongly Interacting

AbstractWe study effects of relic long-lived strongly interacting massive particles (X particles) on big bang nucleosynthesis (BBN). The X particle is assumed to have existed during the BBN epoch, but decayed long before detected. The interaction strength between an X and a nucleon is assumed to be similar to that between nucleons. Rates of nuclear reactions and beta decay of X-nuclei are calculated, and the BBN in the presence of neutral charged X0 particles is calculated taking account of captures of X0 by nuclei. As a result, the X0 particles form bound states with normal nuclei during a relatively early epoch of BBN leading to the production of heavy elements. Constraints on the abundance of X0 are derived from observations of primordial light element abundances. Particle models which predict long-lived colored particles with lifetimes longer than ~200 s are rejected. This scenario prefers the production of 9Be and 10B. There might, therefore, remain a signature of the X particle on primordial abundances of those elements. Possible signatures left on light element abundances expected in four different models are summarized.

scholarly journals The new hybrid BBN model with the photon cooling, X particle, and the primordial magnetic field

2017 ◽  
Vol 26 (08) ◽  
pp. 1741006 ◽  
Author(s):  
Dai G. Yamazaki ◽  
Motohiko Kusakabe ◽  
Toshitaka Kajino ◽  
Grant J. Mathews ◽  
Myung-Ki Cheoun
Keyword(s):  
Magnetic Field ◽  
Energy Density ◽  
Light Element ◽  
Scalar Particle ◽  
Big Bang ◽  
Einstein Condensation ◽  
Supersymmetric Particle ◽  
Element Abundances ◽  
Primordial Magnetic Field ◽  
Parameter Ranges

The Big Bang Nucleosynthesis theory accurately reproduces the abundances of light elements in the universes, except for the 7Li abundance. The calculated 7Li abundance with the baryon-to-photon ratio fixed by the observations of the cosmic microwave background (CMB) is inconsistent with the observed lithium abundances on the surface of metal-poor halo stars, and this problem is called “7Li problem”. Previous studies proposed to resolve this 7Li problem include photon cooling (possibly via the Bose–Einstein condensation of a scalar particle), the decay of a long-lived [Formula: see text] particle (possibly the next-to-lightest supersymmetric particle), or an energy density of a primordial magnetic field (PMF). We review and analyze the results of these solutions both separately and in concert, and the constraint on the [Formula: see text] particles and the PMF parameters from observed light-element abundances with a likelihood analysis. We can discover parameter ranges of the [Formula: see text] particles which can solve the 7Li problem and constrain the energy density of the PMF.

scholarly journals Dark matter annihilation in the universe

2014 ◽  
Vol 30 ◽  
pp. 1460256 ◽  
Author(s):  
Pierre Salati
Keyword(s):  
Dark Matter ◽  
Galactic Halo ◽  
Light Element ◽  
Big Bang ◽  
Microwave Background ◽  
Dark Matter Annihilation ◽  
Element Abundances ◽  
Primordial Plasma ◽  
Relic Abundance ◽  
The Universe

The astronomical dark matter is an essential component of the Universe and yet its nature is still unresolved. It could be made of neutral and massive elementary particles which are their own antimatter partners. These dark matter species undergo mutual annihilations whose effects are briefly reviewed in this article. Dark matter annihilation plays a key role at early times as it sets the relic abundance of the particles once they have decoupled from the primordial plasma. A weak annihilation cross section naturally leads to a cosmological abundance in agreement with observations. Dark matter species subsequently annihilate — or decay — during Big Bang nucleosynthesis and could play havoc with the light element abundances unless they offer a possible solution to the 7 Li problem. They could also reionize the intergalactic medium after recombination and leave visible imprints in the cosmic microwave background. But one of the most exciting aspects of the question lies in the possibility to indirectly detect the dark matter species through the rare antimatter particles — antiprotons, positrons and antideuterons — which they produce as they currently annihilate inside the galactic halo. Finally, the effects of dark matter annihilation on stars is discussed.

Nucleosynthesis

1986 ◽  
Vol 320 (1556) ◽  
pp. 557-564 ◽  
Keyword(s):  
Light Element ◽  
Hubble Constant ◽  
Big Bang ◽  
Element Abundances ◽  
Stellar Nucleosynthesis ◽  
Baryonic Density ◽  
Redshift Surveys ◽  
A Value ◽  
First Case ◽  
The Universe

Both Big-Bang and stellar nucleosynthesis have outcomes related to the density of baryonic matter, but whereas in the first case there is a standard model that makes very precise predictions of light element abundances as a function of the mean density of baryons in the Universe, in the second case various uncertainties permit only very limited conclusions to be drawn. As far as Big-Bang synthesis and the light elements are concerned, existing results on D, 3 He and 7 Li indicate a value of Ω N h 2 0 greater than 0.01 and less than 0.025, where Ω N is the ratio of baryonic density to the closure density and h 0 is the Hubble constant in units of 100 km s -1 Mpc -1 ; probably 0.5 < h 0 < 1. New results on the primordial helium abundance give a still tighter upper limit to Ω N ,Ω N h 2 0 < 0.013, which when compared with redshift surveys giving Ω > 0.05 implies that the observed matter can all be baryonic only if the various uncertainties are stretched to their limits.

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