Results 121 to 130 of about 197,812 (267)

Quadrupole formulae with cosmological constant: comparison

Journal of High Energy Physics
We consider three different approaches (by Ashtekar, Bonga and Kesavan; Hoque and Virmani; and Dobkowski-Ryłko and Lewandowski) to investigate gravitational radiation produced by time changing matter source in de Sitter spacetime.
Denis Dobkowski-Ryłko, Jerzy Lewandowski   +1 more
doaj   +1 more source

COSMOLOGICAL PERTURBATIONS AND THE RUNNING COSMOLOGICAL CONSTANT MODEL [PDF]

International Journal of Modern Physics D, 2012
We study the matter density fluctuations in the running cosmological constant (RCC) model using linear perturbations in the longitudinal gauge. Using this observable, we calculate the growth rate of structures and the matter power spectrum, and compare these results to SDSS data and the available data for linear growth rate.
openaire   +2 more sources

Noble gases and nitrogen in material from asteroid Bennu

Meteoritics &Planetary Science, EarlyView.
Abstract We report the elemental and isotopic abundances of all stable noble gases (helium, neon, argon, krypton, and xenon) in eight particles from asteroid Bennu returned by NASA's OSIRIS‐REx mission. We also report nitrogen abundances and isotopic ratios that were analyzed alongside neon and argon in four additional Bennu particles.
B. Marty, L. Zimmermann, E. Füri, D. V. Bekaert, J. J. Barnes, A. N. Nguyen, H. C. Connolly, D. S. Lauretta   +7 more
wiley   +1 more source

The Solution Cosmological Constant Problem [PDF]

, 2019
The cosmological constant problem arises because the magnitude of vacuum energy density predicted by the Quantum Field Theory is about 120 orders of magnitude larger then the value implied by cosmological observations of accelerating
Foukzon, Jaykov
core  

Cosmological Constant From Degenerate Vacua [PDF]

Physical Review Letters, 2002
Under the hypothesis that the cosmological constant vanishes in the true ground state with lowest possible energy density, we argue that the observed small but finite vacuum-like energy density can be explained if we consider a theory with two or more degenerate perturbative vacua, which are unstable due to quantum tunneling, and if we still live in ...
openaire   +3 more sources

Determining impact angle from the spatial distribution of shock metamorphism: A case study of the Gosses Bluff (Tnorala) impact structure, Australia

Meteoritics &Planetary Science, EarlyView.
Abstract The majority of planetary impacts occur at oblique angles. Impact structures on Earth are commonly eroded or buried, rendering the identification of the direction and angle of impact—using methods such as asymmetries in ejecta distribution, surface topographic expression, central uplift structure, and geophysical anomalies—challenging. In this
Eloise E. Matthews, Auriol S. P. Rae, Thomas Kenkmann, Nicholas E. Timms, Aaron J. Cavosie, Marian B. Holness   +5 more
wiley   +1 more source

Hybrid imploding scalar and ads spacetime

Physics Letters B, 2019
A solution to the massless scalar cosmological constant field equations is presented. The solution has imploding scalar and parts of anti-deSitter or deSitter spacetime as limiting cases.
Mark D. Roberts
doaj   +1 more source

Static recrystallization of shocked calcite in Ries impact breccias

Meteoritics &Planetary Science, EarlyView.
Abstract Calcite is prone to chemical and microstructural modifications, especially after having been strained at high stresses and strain rates, as during hypervelocity impact events. These modifications include precipitation from pore fluid as well as replacement of strained volumes by recrystallization. In calcite aggregates of a metagranite breccia
Claudia A. Trepmann, Fabian Dellefant, Lina Seybold, Wolfgang W. Schmahl, Elena Sturm, Daniel Weidendorfer, Sandro Jahn, Iuliia V. Sleptsova, Stuart A. Gilder   +8 more
wiley   +1 more source

cosmological constant

The cosmological constant (Λ) problem represents a profound inconsistency at the foundationof modern theoretical physics. In this paper, we propose a phenomenological model wherein Λis not a fixed value but rather a dynamic quantity, interpreted as the effective potential energy ofa scalar field coupled to the expansion of the universe.
openaire   +1 more source

Microspherules Formed by Lightning Strikes

Meteoritics &Planetary Science, EarlyView.
Abstract Natural microspherules are formed by high‐temperature processes and are present throughout the geologic record to the present day. We report the discovery of large numbers of microspherules recovered from a rock pavement in the Pilbara region, Western Australia.
M. R. Boyd, M. J. Genge, A. G. Tomkins
wiley   +1 more source