搜索结果: 1-15 共查到“知识库 天文学 theory”相关记录52条 . 查询时间(0.272 秒)
We present a theory for describing the evolution of a galaxy caused by stochastic events such as weak mergers, transient spiral structure, orbiting blobs, etc. This noise excites large-scale patterns ...
Theory of magnetic reconnection in solar and astrophysical plasmas
Theory magnetic reconnection solar astrophysical plasmas
2012/2/23
Magnetic reconnection is a fundamental process in a plasma that facilitates the release of energy stored in the magnetic field by permitting a change in the magnetic topology. In this article we prese...
Pre-big bang collapsing universe from modern Kaluza-Klein theory of gravity
Pre-big bang collapsing universe modern Kaluza-Klein theory gravity
2011/10/18
We study the collapse of the universe described by a scalar field spherically symmetric collapse of a system described by a massless scalar field from a 5D Riemann-flat canonical metric, on which we m...
Asymptotically safe gravity as a scalar-tensor theory and its cosmological implications
Asymptotically gravity scalar-tensor theory cosmological implications
2011/10/14
We study asymptotically safe gravity with Einstein-Hilbert truncation taking into account the renormalization group running of both gravitational and cosmological constants. We show the classical beha...
On the redundancy of operators and the bispectrum in the most general second-order scalar-tensor theory
redundancy operators bispectrum general second-order scalar-tensor theory
2011/10/19
In this short note we explain how to use the linear equation of motions to simplify the third-order action for the cosmological fluctuations. No field redefinition is needed in this exact procedure wh...
We work out an effective theory of accelerated expansion to describe general phenomena of inflation and acceleration (dark energy) in the Universe. Our aim is to determine from theoretical grounds, in...
A sufficient condition for de Sitter vacua in type IIB string theory
moduli stabilization string vacua ux compacti cations
2011/10/18
We derive a sufficient condition for realizing meta-stable de Sitter vacua with small positive cosmological constant within type IIB string theory flux compactifications with spontaneously broken supe...
Manifestly gauge invariant theory of the nonlinear cosmological perturbations in the leading order of the gradient expansion
nonlinear cosmological perturbation, gauge invariance, non-Gaussianity PACS number(s):98.80.Cq
2011/9/29
In the full nonlinear cosmological perturbation theory in the leading order of the gradient expansion, all the types of the gauge invariant perturbation variables are defined. The metric junction cond...
Effective field theory for hydrodynamics: Wess-Zumino term and anomalies in two spacetime dimensions
Effective field theory hydrodynamics:anomalies spacetime dimensions
2011/10/14
We develop the formalism that incorporates quantum anomalies in the effective field theory of non-dissipative fluids. We consider the effect of adding a Wess-Zumino-like term to the low-energy effecti...
Effective field theory for hydrodynamics: thermodynamics, and the derivative expansion
Effective field theory hydrodynamics:thermodynamics derivative expansion
2011/10/14
We consider the low-energy effective field theory describing the infrared dynamics of non-dissipative fluids. We extend previous work to accommodate conserved charges, and we clarify the matching betw...
Cosmological Perturbation Theory With Background Anisotropic Curvature
Cosmological Perturbation Theory Background Anisotropic Curvature
2011/10/18
The theory of cosmological perturbations is extended to spacetimes displaying isotropic expansion but anisotropic curvature. The perturbed Einstein equation and Boltzmann equations for massless and ma...
Homochirality through Photon-Induced Melting of RNA/DNA: the Thermodynamic Dissipation Theory of the Origin of Life
Homochirality Photon-Induced Melting RNA/DNA
2011/1/13
The homochirality of the molecules of life has been a vexing problem with no generally accepted solution to date. Since a racemic mixture of chiral nucleotides frustrates the extension and replication...
Inflation in string theory: a graceful exit to the real world
Inflation in string theory the real world
2011/1/13
The most important criteria for a successful inflation are to explain the observed temperature anisotropy in the cosmic microwave background radiation, and exiting inflation in a vacuum where it can ...
We propose a unified theory of dark matter (DM) genesis and baryogenesis. It explains the observed link between the DM density and the baryon density, and is fully testable by a combination of collid...
Theory of Feedback in Clusters and Molecular Cloud Turbulence
Feedback in Clusters Molecular Cloud Turbulence
2011/1/11
I review recent numerical and analytical work on the feedback from both low- and high-mass cluster stars into their gasoeus environment. The main conclusions are that i) outflow driving appears capabl...