1,719 research outputs found
A theory of thin shells with orbiting constituents
The self-gravitating, spherically symmetric thin shells built of orbiting
particles are sstudied. Two new features are found. One is the minimal possible
value for an angular momentum of particles, above which elleptic orbits become
possible. The second is the coexistence of both the wormhole solutions and the
elleptic or hyperbolic orbits for the same values of the parameters (but
different initial conditions). Possible applications of these results to
astrophysics and quantum black holes are briefly discussed.Comment: 22 pages, Latex, 10 eps figures. CERN preprint no. CERN-TH 2000-16
A new paradigm of governance for a carbon-pricing system
Throughout its life, the United Nations has played a pioneering role in the world of ideas. COP21 – also known as Paris 2015 – shows the path for the United Nations to establish a new governance that will enforce the compliance of a new planetary carbon-pricing system. Maintaining global warming below 2 °C means implementing an efficient carbon-pricing system, supported by effective measures promoting a green energy transition. A planetary carbon governance yields a number of new insights that include the following: (1) a bonus-malus system with a fixed signal price for carbon, (2) a planetary carbon market that will gather existing regional carbon markets, (3) a hybrid carbon-pricing system linking a carbon tax and a carbon market for advanced countries and (4) a support mechanism for emerging and developing countries to assist them with a carbon-pricing system. This new governance will promote an energy transition plan. In the COP21 context, responsible policymaking requires key characteristics for the enforcement of a successful planetary carbon-pricing system
Vacuum decay via Lorentzian wormholes
We speculate about the spacetime description due to the presence of
Lorentzian wormholes (handles in spacetime joining two distant regions or other
universes) in quantum gravity. The semiclassical rate of production of these
Lorentzian wormholes in Reissner-Nordstr\"om spacetimes is calculated as a
result of the spontaneous decay of vacuum due to a real tunneling
configuration. In the magnetic case it only depends on the field theoretical
fine structure constant. We predict that the quantum probability corresponding
to the nucleation of such geodesically complete spacetimes should be actually
negligible in our physical Universe
Construction of Self-Adjoint Berezin-Toeplitz Operators on Kahler Manifolds and a Probabilistic Representation of the Associated Semigroups
We investigate a class of operators resulting from a quantization scheme
attributed to Berezin. These so-called Berezin-Toeplitz operators are defined
on a Hilbert space of square-integrable holomorphic sections in a line bundle
over the classical phase space. As a first goal we develop self-adjointness
criteria for Berezin-Toeplitz operators defined via quadratic forms. Then,
following a concept of Daubechies and Klauder, the semigroups generated by
these operators may under certain conditions be represented in the form of
Wiener-regularized path integrals. More explicitly, the integration is taken
over Brownian-motion paths in phase space in the ultra-diffusive limit. All
results are the consequence of a relation between Berezin-Toeplitz operators
and Schrodinger operators defined via certain quadratic forms. The
probabilistic representation is derived in conjunction with a version of the
Feynman-Kac formula.Comment: AMS-LaTeX, 30 pages, no figure
Dynamics of a thin shell in the Reissner-Nordstrom metric
We describe the dynamics of a thin spherically symmetric gravitating shell in
the Reissner-Nordstrom metric of the electrically charged black hole. The
energy-momentum tensor of electrically neutral shell is modelled by the perfect
fluid with a polytropic equation of state. The motion of a shell is described
fully analytically in the particular case of the dust equation of state. We
construct the Carter-Penrose diagrams for the global geometry of the eternal
black hole, which illustrate all possible types of solutions for moving shell.
It is shown that for some specific range of initial parameters there are
possible the stable oscillating motion of the shell transferring it
consecutively in infinite series of internal universes. We demonstrate also
that this oscillating type of motion is possible for an arbitrary polytropic
equation of state on the shell.Comment: 17 pages, 7 figure
Vacuum shell in the Schwarzschild-de Sitter world
We construct the classification scheme for all possible evolution scenarios
and find the corresponding global geometries for dynamics of a thin spherical
vacuum shell in the Schwarzschild-de Sitter metric. This configuration is
suitable for the modelling of vacuum bubbles arising during cosmological phase
transitions in the early Universe. The distinctive final types of evolution
from the local point of view of a rather distant observer are either the
unlimited expansion of the shell or its contraction with a formation of black
hole (with a central singularity) or wormhole (with a baby universe in
interior).Comment: 15 pages, 8 figure
Intertwining operator for Calogero-Moser-Sutherland system
We consider generalised Calogero-Moser-Sutherland quantum Hamiltonian
associated with a configuration of vectors on the plane which is a union
of and root systems. The Hamiltonian depends on one parameter.
We find an intertwining operator between and the Calogero-Moser-Sutherland
Hamiltonian for the root system . This gives a quantum integral for of
order 6 in an explicit form thus establishing integrability of .Comment: 24 page
Resonating Valence Bond Theory of Superconductivity for Dopant Carriers: Application to the Cobaltates
Within the -- model Hamiltonian we present a RVB mean field theory
directly in terms of dopant particles. We apply this theory to
and show that the
resulting phase diagram versus doping is in qualitative agreement with
the experimental results
Mass of perfect fluid black shells
The spherically symmetric singular perfect fluid shells are considered for
the case of their radii being equal to the event horizon (the black shells). We
study their observable masses, depending at least on the three parameters,
viz., the square speed of sound in the shell, instantaneous radial velocity of
the shell at a moment when it reaches the horizon, and integration constant
related to surface mass density. We discuss the features of black shells
depending on an equation of state.Comment: 1 figure, LaTeX; final version + FA
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