Cosmological Time Evolution Research Articles

Cosmological time evolution of the Higgs mass and gravitational waves

We point out that gravitational wave detectors such as LISA have the potential of probing a cosmological time evolution of the Higgs boson self-coupling constant [Formula: see text] and thus the Higgs boson’s mass [Formula: see text]. The phase transition of the Standard Model could have been a first order one if the Higgs mass was below 72 GeV at a temperature [Formula: see text] GeV. Gravitational waves could thus have been produced during the electroweak phase transition. A discovery by LISA of a stochastic background of gravitational waves with a characteristic frequency [Formula: see text] Hz could be interpreted as a sign that the Higgs boson self-coupling constant was smaller in the past. This interpretation would be particularly tempting if the Large Hadron Collider did not discover any physics beyond the Standard Model by the time such waves are seen. The same mechanism could also account for baryogenesis.

On the flux of high-energy cosmogenic neutrinos and the influence of the extragalactic magnetic field

ABSTRACT Cosmogenic neutrinos originate from interactions of cosmic rays propagating through the universe with cosmic background photons. Since both high-energy cosmic rays and cosmic background photons exist, the existence of high-energy cosmogenic neutrinos is certain. However, their flux has not been measured so far. Therefore, we calculated the flux of high-energy cosmogenic neutrinos arriving at the Earth on the basis of elaborate 4D simulations that take into account three spatial degrees of freedom and the cosmological time-evolution of the universe. Our predictions for this neutrino flux are consistent with the recent upper limits obtained from large-scale cosmic-ray experiments. We also show that the extragalactic magnetic field has a strong influence on the neutrino flux. The results of this work are important for the design of future neutrino observatories, since they allow to assess the detector volume and observation time that are necessary to detect high-energy cosmogenic neutrinos in the near future. An observation of such neutrinos would push multimessenger astronomy to hitherto unachieved energy scales.

Cosmological evolution of the Higgs boson\u2019s vacuum expectation value

We point out that the expansion of the universe leads to a cosmological time evolution of the vacuum expectation of the Higgs boson. Within the standard model of particle physics, the cosmological time evolution of the vacuum expectation of the Higgs leads to a cosmological time evolution of the masses of the fermions and of the electroweak gauge bosons, while the scale of Quantum Chromodynamics (QCD) remains constant. Precise measurements of the cosmological time evolution of mu =m_e/m_p, where m_e and m_p are, respectively, the electron and proton mass (which is essentially determined by the QCD scale), therefore provide a test of the standard models of particle physics and of cosmology. This ratio can be measured using modern atomic clocks.

Cosmological evolution of fundamental constants: From theory to experiment

In this paper, we discuss a possible cosmological time evolution of fundamental constants from the theoretical and experimental point of views. On the theoretical side, we explain that such a cosmological time evolution is actually something very natural which can be described by mechanisms similar to those used to explain cosmic inflation. We then discuss implications for grand unified theories, showing that the unification condition of the gauge coupling could evolve with cosmological time. Measurements of the electron-to-proton mass ratio can test grand unified theories using low energy data. Following the theoretical discussion, we review the current status of precision measurements of fundamental constants and their potential cosmological time dependence.

Holographic inflation and the conservation of ζ

In a holographic description of inflation, cosmological time evolution in the bulk is expected to correspond to the renomalization group (RG) flow in a dual boundary theory. Here, we analyze this expectation by computing the correlation functions of the curvature perturbation $\zeta$ holographically. For this purpose, we use a deformed conformal field theory at the boundary, with a single deformation operator. In standard single field models of inflation, $\zeta$ is known to be conserved at large scales under very general conditions. However, we find that this is not generically the case in the dual description. The requirement that higher correlators of $\zeta$ should be conserved severely restricts the possibilities for the RG flow. With such restriction, the power spectrum $P_\zeta$ must follow an exact power law, at least within the regime of validity of conformal perturbation theory.

Time-dependent spherically symmetric covariant Galileons

We study spherically symmetric solutions of the cubic covariant Galileon model in curved spacetime in presence of a matter source, in the test scalar field approximation. We show that a cosmological time evolution of the Galileon field gives rise to an induced matter-scalar coupling, due to the Galileon-graviton kinetic braiding, therefore the solution for the Galileon field is non trivial even if the bare matter-scalar coupling constant is set to zero. The local solution crucially depends on the asymptotic boundary conditions, and in particular, Minkowski and de Sitter asymptotics correspond to different branches of the solution. We study the stability of these solutions, namely, the well-posedness of the Cauchy problem and the positivity of energy for scalar and tensor perturbations, by diagonalizing the kinetic terms of the spin-2 and spin-0 degrees of freedom. In addition, we find that in presence of a cosmological time evolution of the Galileon field, its kinetic mixing with the graviton leads to a friction force, resulting to efficient damping of scalar perturbations within matter.

Constraints on Shift-Symmetric Scalar-Tensor Theories with a Vainshtein Mechanism from Bounds on the Time Variation ofG

We show that the current bounds on the time variation of the Newton constant G can put severe constraints on many interesting scalar-tensor theories which possess a shift symmetry and a nonminimal matter-scalar coupling. This includes, in particular, Galileon-like models with a Vainshtein screening mechanism. We underline that this mechanism, if efficient to hide the effects of the scalar field at short distance and in the static approximation, can in general not alter the cosmological time evolution of the scalar field. This results in a locally measured time variation of G which is too large when the matter-scalar coupling is of order one.

Planck’s constant variation as a cosmological evolution test for the early universe

A conjecture on a hierarchical cosmological time evolution of Planck’s constant has been accepted. This presumed phenomenon might be responsible for the cosmological high redshifts as an alternative mechanism instead of the Doppler effect. The Bohr radius of a hydrogen atom and the probability of alpha decay of atomic nuclei have been estimated: both results are in sufficient consent with observational data concerning the light elements abundance in the early Universe.

Mass, entropy, and holography in asymptotically de Sitter spaces

We propose a novel prescription for computing the boundary stress tensor and charges of asymptotically de Sitter (dS) spacetimes from data at early or late time infinity. If there is a holographic dual to dS spaces, defined analogously to the AdS/conformal field theory correspondence, our methods compute the (Euclidean) stress tensor of the dual. We compute the masses of Schwarzschild--de Sitter black holes in four and five dimensions, and the masses and angular momenta of Kerr--de Sitter spaces in three dimensions. All these spaces are less massive than de Sitter space, a fact which we use to qualitatively and quantitatively relate de Sitter entropy to the degeneracy of possible dual field theories. Our results in general dimensions lead to a conjecture: Any asymptotically de Sitter spacetime with mass greater than de Sitter space has a cosmological singularity. Finally, if a dual to de Sitter space exists, the trace of our stress tensor computes the renormalized group (RG) equation of the dual field theory. Cosmological time evolution corresponds to RG evolution in the dual. The RG evolution of the c function is then related to changes in accessible degrees of freedom in an expanding universe.

Cosmological time evolution in the Newtonian dynamics of compact celestial bodies

view Abstract Citations (7) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Cosmological Time Evolution in the Newtonian Dynamics of Compact Celestial Bodies Nordtvedt, K. Abstract Compact body gravitational clocks and rules involving orbital dynamics of bodies possessing substantial gravitational self-energy are examined. The new physics that can be measured in such compact body systems when they are compared to the other spacetime standards is modeled, and new nonperturbative, but rather cosmological, constraints are formulated that can be placed on gravitational theory by the intercomparisons between different spacetime standards. Using empirical bounds on anomalous orbital period evolution for the binary pulsar system PSR 1913 + 16, a limit can be placed on time evolution of the PPN coefficients gamma and beta of not greater than 5 x 10 exp -11/yr, which becomes an additional constraint on alternative gravitational theories in the nonperturbative cosmological domain, particularly on theories designed to duplicate general relativity at first perturbative post-Newtonian order yet differing finitely at higher orders. Publication: The Astrophysical Journal Pub Date: April 1993 DOI: 10.1086/172487 Bibcode: 1993ApJ...407....5N Keywords: Celestial Bodies; Cosmology; Newton Theory; Relativity; Equations Of Motion; Gravitation Theory; Astrophysics; COSMOLOGY: THEORY; RELATIVITY full text sources ADS |