Mercedes E. Mosquera

Primordial Nucleosynthesis with Varying Fundamental Constants: A Semianalytical Approach

Using the semianalytic method proposed by Esmailzadeh and coworkers we calculate the abundances of the light elements produced during primordial nucleosynthesis assuming that the gauge coupling constants of the fundamental interactions may vary. We analyze the dependence of the nucleon masses, nuclear binding energies, and cross sections involved in the calculation of the abundances with the fundamental constants assuming the chiral limit of QCD. We obtain the abundances of light elements as a function of the fundamental constants. Finally, using the observational data of D, 3He, 4He, and 7Li, we estimate constraints on the variation of the fundamental constants between the time of primordial nucleosynthesis and the present. All observational abundances and the WMAP estimate of the baryon density can be fitted to the theoretical predictions with varying coupling constants. The possible systematic errors in the observational data preclude stronger conclusions.

Early universe constraints on time variation of fundamental constants

We study the time variation of fundamental constants in the early Universe. Using data from primordial light nuclei abundances, cosmic microwave background, and the 2dFGRS power spectrum, we put constraints on the time variation of the fine structure constant {alpha} and the Higgs vacuum expectation value without assuming any theoretical framework. A variation in leads to a variation in the electron mass, among other effects. Along the same line, we study the variation of {alpha} and the electron mass m{sub e}. In a purely phenomenological fashion, we derive a relationship between both variations.

Helium and deuterium abundances as a test for the time variation of the fine structure constant and the higgs vacuum expectation value

We use the semi-analytic method of Esmailzadeh et al (1991 Astrophys. J. 378 504–18) to calculate the abundances of helium and deuterium produced during Big Bang nucleosynthesis assuming the fine structure constant and the Higgs vacuum expectation value may vary in time. We analyse the dependence on the fundamental constants of the nucleon mass, nuclear binding energies and cross sections involved in the calculation of the abundances. Unlike previous works, we do not assume the chiral limit of QCD. Rather, we take into account the quark masses and consider the one-pion exchange potential, within perturbation theory, for the proton–neutron scattering. However, we do not consider the time variation of the strong interactions scale but attribute the changes in the quark masses to the temporal variation of the Higgs vacuum expectation value. Using the observational data of the helium and deuterium, we put constraints on the variation of the fundamental constants between the time of nucleosynthesis and the present time.

Time variation of the fine structure constant in the early universe and the Bekenstein model

Aims. We calculate the bounds on the variation in the fine structure constant at the time of primordial nucleosynthesis and at the time of neutral hydrogen formation. We used these bounds and other bounds from the late universe to test the Bekenstein model. Methods. We modified the Kawano code, CAMB, and CosmoMC to include the possible variation in the fine structure constant. We used observational primordial abundances of D, 4 He, and 7 Li, recent data from the cosmic microwave background, and the 2dFGRS power spectrum, to obtain bounds on the variation in α. We calculated a piecewise solution to the scalar field equation of the Bekenstein model in two different regimes: i) matter and radiation, ii) matter and cosmological constant. We match both solutions with the appropriate boundary conditions. We performed a statistical analysis, using the bounds obtained from the early universe and other bounds from the late universe to constrain the free parameters of the model. Results. Results are consistent with no variation in α for the early universe. Limits on α are inconsistent with the scale length of the theory l being larger than the Planck scale. Conclusions. In order to fit all observational and experimental data, the assumption l > Lp implied in Bekenstein’s model has to be relaxed.

Effect of the variation of the Higgs vacuum expectation value upon the deuterium binding energy and primordial abundances of D and 4He

Aims. We calculate the constraints on the time variation of the Higgs vacuum expectation value from Big Bang Nucleosynthesis. Methods. Starting from the calculation of the deuterium binding-energy, as a function of the pion-mass and using the NN-Reid 93 potential, we calculate the abundances of primordial D and 4 He by modifying Kawano’s code. The Higgs vacuum expectation value (v) and the baryon to photon ratio (ηB) enter the calculation as free parameters. By using the observational data of D and 4 He, we set constraints on ηB and on the variation ofv, relative to a constant value of ΛQCD.

Time Variation of the Electron Mass in the Early Universe and the Barrow-Magueijo Model

We put limits on the time variation of the electron mass in the early universe using observational primordial abundances of D, He4 and Li7, recent data from the Cosmic Microwave Background and the 2dFGRS power spectrum. Furthermore, we use these constraints together with other astronomical and geophysical bounds from the late universe to test Barrow-Magueijos model for the variation in m_e. From our analysis we obtain -0.615 < G\omega/c^4 < -0.045 (3\sigma interval) in disagreement with the result obtained in the original paper.

New cosmological constraints on the variation of fundamental constants: the fine structure constant and the Higgs vacuum expectation value

Aims. We study the time variation of the fine structure constant, α, and the Higgs vacuum expectation value v, during the Big Bang nucleosynthesis (BBN). Methods. We computed primordial abundances of light nuclei produced during the BBN stage by including resonances in the leading reaction rates which reduce the primordial abundance of beryllium. We performed this calculation considering that α and v may vary during the BBN. Using observable data on deuterium, 4 He, and 7 Li, we set constraints on the variation of the fundamental constants. Results. Results indicate a null variation of α and v, while the best-fit value for the baryon-to-photon ratio agrees well with the WMAP value. Conclusions. We found that the variation of α is null within 3σ, the variation of v is null within 6σ, and the preferred value of the baryon-to-photon ratio is in good agreement, within 3σ, with the value extracted using the WMAP data. We improve the fits respect to previous works.

Sterile neutrinos and Big Bang Nucleosynthesis in the 3 + 1 scheme

We study the effects of adding a sterile neutrino to three active neutrinos (3 + 1 scheme) in the calculation of primordial abundances. Taking the normalization constant (a) of the occupation factor of the sterile neutrino and the active-sterile mixing angle (ϕ) as free parameters, we calculate the neutrino distribution function and primordial abundances of light nuclei. We set constrains on these parameters by using the available data on the abundances of D, 4He and 7Li. Results are consistent with small values of a and ϕ. The extracted value of the baryon-to-photon ratio (ηB), which is constrained by the Wilkinson Microwave Anisotropy Probe (WMAP) value

Time variation of the fine structure constant and of the Higgs vacuum expectation value on cosmological time scales

\eta_B^{\rm WMAP}

Effects of active–sterile neutrino mixing during primordial nucleosynthesis

, and Planck observations, depends strongly on the inclusion of the lithium data in the fit.