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We show that the predicted primordial helium production is significantly reduced when new measurements of the neutron lifetime and the implied enhancement in the weak reaction rates are included in big-bang nucleosynthesis. Therefore, even…

Astrophysics · Physics 2009-11-10 G. J. Mathews , T. Kajino , T. Shima

Extremely low metallicity HII regions have been observed with the goal of determining the primordial helium abundance ($Y_{\rm p}$). $Y_{\rm p}$, combined with standard big bang nucleosynthesis and the half-life of the neutron, provides a…

In the standard Big Bang cosmology the canonical value for the ratio of relic neutrinos to CMB photons is 9/11. Within the framework of the Standard Model of particle physics there are small corrections, in sum about 1%, due to slight…

Astrophysics · Physics 2009-10-30 Robert E. Lopez , Scott Dodelson , Andrew Heckler , Michael S. Turner

We present the results of analysis of constraints on cosmological parameters from cosmic microwave background (CMB) alone and in combination with galaxy cluster baryon fraction assuming inflation--generated adiabatic scalar fluctuations.…

Astrophysics · Physics 2009-11-06 M. Douspis , A. Blanchard , R. Sadat , J. G. Bartlett , M. Le Dour

The relic abundances of the light elements synthesized during the first few minutes of the evolution of the Universe provide unique probes of cosmology and the building blocks for stellar and galactic chemical evolution, while also enabling…

Astrophysics · Physics 2015-06-24 Gary Steigman

The Cosmic Neutrino Background (CNB) is a definite prediction of the standard cosmological model and its direct discovery would represent a milestone in cosmology and neutrino physics. In this work, we consider the capture of relic…

High Energy Physics - Phenomenology · Physics 2022-03-14 James Alvey , Miguel Escudero , Nashwan Sabti , Thomas Schwetz

For a brief time in its early evolution the Universe was a cosmic nuclear reactor. The expansion and cooling of the Universe limited this epoch to the first few minutes, allowing time for the synthesis in astrophysically interesting…

Cosmology and Nongalactic Astrophysics · Physics 2010-09-27 Gary Steigman

The standard cosmological model, LCDM, provides an excellent fit to Cosmic Microwave Background (CMB) data. However, the model has well known problems. For example, the cosmological constant, is fine-tuned to 1 part in 10^100 and the cold…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 T. Shanks , R. W. F. Johnson , J. A. Schewtschenko , J. R. Whitbourn

The possibility that the so-called "lithium problem", i.e. the disagreement between the theoretical abundance predicted for primordial $^7$Li assuming standard nucleosynthesis and the value inferred from astrophysical measurements, can be…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-03 Laura Salvati , Luca Pagano , Massimiliano Lattanzi , Martina Gerbino , Alessandro Melchiorri

Neutrinos that decay leave their imprint on the cosmic microwave background. We calculate the CMB anisotropy for the full range of decaying neutrino parameter space, and investigate the ability of future experiments like MAP and Planck to…

Astrophysics · Physics 2007-05-23 Robert E. Lopez

We present a new constraint on the effective number of relativistic species in the early universe, $N_{\rm eff}$, by combining recent primordial helium abundance measurements from the Large Binocular Telescope $Y_p$ Project with primordial…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-23 Samuel Goldstein , J. Colin Hill

We evaluate the ability of future cosmic microwave background (CMB) experiments to measure the power spectrum of large scale structure using quadratic estimators of the weak lensing deflection field. We calculate the sensitivity of upcoming…

Astrophysics · Physics 2009-11-13 Julien Lesgourgues , Laurence Perotto , Sergio Pastor , Michel Piat

We investigate the effects that arise from the inclusion of Weylian boundary terms in the Einstein gravitational field equations in the Big Bang Nucleosynthesis (BBN) framework. With the help of the generalized Friedmann equations for a…

General Relativity and Quantum Cosmology · Physics 2026-04-28 Teodora M. Matei , Cristian Croitoru , Tiberiu Harko

In the light of the recent WMAP results we update the constraints on a class of non standard BBN models with a simultaneous combination of non standard neutrino distributions and extra effective number of neutrinos in the expansion rate.…

Astrophysics · Physics 2009-11-07 P. Di Bari

The primordial abundance of $^4$He plays a central role in big-bang nucleosynthesis (BBN) and in the cosmic microwave background (CMB). The LBT $Y_{\rm p}$ Project's new measurement of the primordial $^4$He mass fraction $Y_{\rm p} =0.2458…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-02 Tsung-Han Yeh , Keith A. Olive , Brian D. Fields , Erik Aver , Richard W. Pogge , Noah S. J. Rogers , Evan D. Skillman , Miqaela K. Weller

In this study we present a comprehensive sensitivity atlas for Big Bang Nucleosynthesis (BBN) in which we quantify the dependence of the primordial abundances of helium-4, deuterium, and lithium-7 as well as $N_{\rm{eff}}$ on variations in…

High Energy Physics - Phenomenology · Physics 2026-03-25 Anne-Katherine Burns

Many attempts to solve the Hubble tension with extended cosmological models combine an enhanced relic radiation density, acting at the level of background cosmology, with new physical ingredients affecting the evolution of cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-16 Nils Schöneberg , Julien Lesgourgues , Deanna C. Hooper

The angular power spectrum of the cosmic microwave background (CMB) contains information on virtually all cosmological parameters of interest, including the geometry of the Universe ($\Omega$), the baryon density, the Hubble constant ($h$),…

Astrophysics · Physics 2009-10-28 Gerard Jungman , Marc Kamionkowski , Arthur Kosowsky , David N. Spergel

Recent cosmological observations have provided numerous new observations with increasing precision that have led to the era of precision cosmology. The exquisite quality of these observations opens new possibilities towards measuring…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-14 Brahim Lamine , Yacob Ozdalkiran , Louis Mirouze , Furkan Erdogan , Stéphane Ilic , Isaac Tutusaus , Raphael Kou , Alain Blanchard

Constraints on neutrino masses are estimated based on future observations of the cosmic microwave background (CMB) including the B-mode polarization produced by CMB lensing using the Planck satellite, and baryon acoustic oscillations…

Cosmology and Nongalactic Astrophysics · Physics 2013-09-13 Koichi Hirano