697 research outputs found
Simplest cosmological model with the scalar field II. Influence of cosmological constant
Continuing the investigation of the simplest cosmological model with the
massive real scalar non-interacting inflaton field minimally coupled to gravity
we study an influence of the cosmological constant on the behaviour of
trajectories in closed minisuperspace Friedmann-Robertson-Walker model. The
transition from chaotic to regular behaviour for large values of cosmological
constant is discussed. Combining numerical calculations with qualitative
analysis both in configuration and phase space we present a convenient
classification of trajectories.Comment: 12 pages with 2 gif figures and 2 eps figures, mprocl.sty, To appear
in International Journal of Modern Physics
Quantum Cosmology and Conformal Invariance
According to Belinsky, Khalatnikov and Lifshitz, gravity near a space-like
singularity reduces to a set of decoupled one-dimensional mechanical models at
each point in space. We point out that these models fall into a class of
conformal mechanical models first introduced by de Alfaro, Fubini and Furlan
(DFF). The deformation used by DFF to render the spectrum discrete corresponds
to a negative cosmological constant. The wave function of the universe is the
zero-energy eigenmode of the Hamiltonian, also known as the spherical vector of
the representation of the conformal group SO(1,2). A new class of conformal
quantum mechanical models is constructed, based on the quantization of
nilpotent coadjoint orbits, where the conformal group is enhanced to an ADE
non-compact group for which the spherical vector is known.Comment: 4 pages, latex2e, uses revtex
Boundary Value Problem for Black Rings
We study the boundary value problem for asymptotically flat stationary black
ring solutions to the five-dimensional vacuum Einstein equations. Assuming the
existence of two additional commuting axial Killing vector fields and the
horizon topology of , we show that the only asymptotically flat
black ring solution with a regular horizon is the Pomeransky-Sen'kov black ring
solution.Comment: 21 pages, 1 figur
The generality of inflation in some closed FRW models with a scalar field
The generality of inflation in closed FRW Universe is studied for the models
with a scalar field on a brane and with a complex scalar field. The results
obtained are compared with the previously known results for the model with a
scalar field and a perfect fluid. The influence of the measure chosen in the
initial condition space on the ratio of inflationary solution is described.Comment: 15 pages with 5 eps figures; small corrections in text; final version
to appear in Int. J. Mod. Phys.
The Black Di-Ring: An Inverse Scattering Construction
We use the inverse scattering method (ISM) to derive concentric
non-supersymmetric black rings. The approach used here is fully
five-dimensional, and has the modest advantage that it generalizes readily to
the construction of more general axi-symmetric solutions.Comment: v3: 2 subsections added, typos fixed, more refs, journal version. v4:
a transcription error in the ADM mass fixe
Brane Inflation is Attractive
We study the phase space of initial conditions for brane inflation, and find
that including the effects of the Dirac-Born-Infeld (DBI) kinetic term
dramatically improves previous estimates on the amount of fine tuning of
initial conditions necessary for inflation, even for models dominated by slow
roll. Two effects turn out to be important for the phase space analysis:
restrictions on the total available phase space due to UV effects in brane
inflation, and the extension of the inflationary attractor to the DBI
inflationary regime. We compare the amount of initial conditions fine tuning
required for a brane inflation model and its standard field theory counterpart
and find that brane inflation decreases the required tuning by several orders
of magnitude.Comment: 20 pages, 6 figures; v2. references added, typos corrected,
discussion clarified; v3. some numbers changed, discussion on phase space
fine tuning slightly modifie
Joint Probabilities Reproducing Three EPR Experiments On Two Qubits
An eight parameter family of the most general nonnegative quadruple
probabilities is constructed for EPR-Bohm-Aharonov experiments when only 3
pairs of analyser settings are used. It is a simultaneous representation of 3
Bohr-incompatible experimental configurations valid for arbitrary quantum
states.Comment: Typo corrected in abstrac
Reduction without reduction: Adding KK-monopoles to five dimensional stationary axisymmetric solutions
We present a general method to add KK-monopole charge to any asymptotically
flat stationary axisymmetric solution of five dimensional General Relativity.
The technique exploits the underlying SL(3,R) invariance of the system by
identifying a particular element of the symmetry group which changes the
asymptotic boundary condition and adds KK-monopole charge. Furthermore, we
develop a set of technical tools which allow us to apply the SL(3,R)
transformations to solutions produced by the Inverse Scattering method. As an
example of our methods, we construct the exact solution describing a static
black ring carrying KK-monopole charge.Comment: 36 pages, 3 figures, LaTeX, minor typos fixe
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