3,118 research outputs found
Child universes UV regularization?
It is argued that high energy density excitations, responsible for UV
divergences in quantum field theories, including quantum gravity, are likely to
be the source of child universes which carry them out of the original space
time. This decoupling prevents these high UV excitations from having any
influence on physical amplitudes. Child universe production could therefore be
responsible for UV regularization in quantum field theories which takes into
account gravitational effects. Also child universe production in the last
stages of black hole evaporation, the prediction of absence of tranplanckian
primordial perturbations, connection to the minimum length hypothesis and in
particular connection to the maximal curvature hypothesis are discussed.Comment: 6 pages, RevTex, discussion to the maximum curvature hypothesis adde
Wormholes and Child Universes
Evidence to the case that classical gravitation provides the clue to make
sense out of quantum gravity is presented. The key observation is the existence
in classical gravitation of child universe solutions or "almost" solutions,
"almost" because of some singularity problems. The difficulties of these child
universe solutions due to their generic singularity problems will be very
likely be cured by quantum effects, just like for example "almost" instanton
solutions are made relevant in gauge theories with breaking of conformal
invariance. Some well motivated modifcations of General Relativity where these
singularity problems are absent even at the classical level are discussed. High
energy density excitations, responsible for UV divergences in quantum field
theories, including quantum gravity, are likely to be the source of child
universes which carry them out of the original space time. This decoupling
could prevent these high UV excitations from having any influence on physical
amplitudes. Child universe production could therefore be responsible for UV
regularization in quantum field theories which take into account
semiclassically gravitational effects. Child universe production in the last
stages of black hole evaporation, the prediction of absence of tranplanckian
primordial perturbations, connection to the minimum length hypothesis and in
particular the connection to the maximal curvature hypothesis are discussed.
Some discussion of superexcited states in the case these states are Kaluza
Klein excitations is carried out. Finally, the posibility of obtaining "string
like" effects from the wormholes associated with the child universes is
discussed.Comment: Talk presented at the IWARA 2009 Conference, Maresias, Brazil,
October 2009, accepted for publication in the proceedings, World Scientific
format, 8 page
Study of the spring and autumn daemon-flux maxima at the Baksan Neutrino Observatory
Detection of daemons in low-background conditions in September 2005 and March
2006 has provided evidence for the expected to occur at that times maxima in
the flux of daemons with V ~ 10-15 km s-1, which hit the Earth from near-Earth,
almost circular heliocentric orbits. The ability of some FEU-167-1 PM tubes
with a thicker inner Al coating to detect directly daemon passage through them
has also been demonstrated, an effect increasing ~100-fold the detector
efficiency. As a result, the daemon flux recorded at the maxima was increased
from ~10-9 to ~10-7 cm-2 s-1. The intensity and direction of the flux during
maxima depend on the time of day and latitude of observations (therefore,
synchronous measurements in the Northern and Southern Earth's hemispheres are
desirable). All the experimental results obtained either support the
conclusions following from the daemon paradigm or find a simple interpretation
within it.Comment: 15 pages, including 8 figures and 3 table
A non-singular black hole model as a possible end-product of gravitational collapse
In this paper we present a non-singular black hole model as a possible
end-product of gravitational collapse. The depicted spacetime which is type
[II,(II)], by Petrov classification, is an exact solution of the Einstein
equations and contains two horizons. The equation of state in the radial
direction, is a well-behaved function of the density and smoothly reproduces
vacuum-like behavior near r=0 while tending to a polytrope at larger r, low
density, values. The final equilibrium configuration comprises of a de
Sitter-like inner core surrounded by a family of 2-surfaces of matter fields
with variable equation of state. The fields are all concentrated in the
vicinity of the radial center r=0. The solution depicts a spacetime that is
asymptotically Schwarzschild at large r, while it becomes de Sitter-like for
vanishing r. Possible physical interpretations of the macro-state of the black
hole interior in the model are offered. We find that the possible state admits
two equally viable interpretations, namely either a quintessential intermediary
region or a phase transition in which a two-fluid system is in both dynamic and
thermodynamic equilibrium. We estimate the ratio of pure matter present to the
total energy and in both (interpretations) cases find it to be virtually the
same, being 0.83. Finally, the well-behaved dependence of the density and
pressure on the radial coordinate provides some insight on dealing with the
information loss paradox.Comment: 12 Pages, 1 figure. Accepted for publication in Phys. Rev.
Unitary quantization and para-Fermi statistics of order two
A connection between a unitary quantization scheme and para-Fermi statistics
of order 2 is considered. An appropriate extension of Green's ansatz is
suggested. This extension allows one to transform bilinear and trilinear
commutation relations for the annihilation and creation operators of two
different para-Fermi fields and into identity. The way of
incorporating para-Grassmann numbers into a general scheme of
uniquantization is also offered. For parastatistics of order 2 a new fact is
revealed, namely, the trilinear relations containing both the para-Grassmann
variables and the field operators , under a certain
invertible mapping go over into the unitary equivalent relations, where
commutators are replaced by anticommutators and vice versa. It is shown that
the consequence of this circumstance is the existence of two alternative
definitions of the coherent state for para-Fermi oscillators. The Klein
transformation for Green's components of the operators , is
constructed in an explicit form that enables us to reduce the initial
commutation rules for the components to the normal commutation relations of
ordinary Fermi fields. A nontrivial connection between trilinear commutation
relations of the unitary quantization scheme and so-called Lie-supertriple
system is analysed. A brief discussion of the possibility of embedding the
Duffin-Kemmer-Petiau theory into the unitary quantization scheme is provided.Comment: 44 pages, the version published in J. Exp. Theor. Phy
Simulating quantum computation by contracting tensor networks
The treewidth of a graph is a useful combinatorial measure of how close the
graph is to a tree. We prove that a quantum circuit with gates whose
underlying graph has treewidth can be simulated deterministically in
time, which, in particular, is polynomial in if
. Among many implications, we show efficient simulations for
log-depth circuits whose gates apply to nearby qubits only, a natural
constraint satisfied by most physical implementations. We also show that
one-way quantum computation of Raussendorf and Briegel (Physical Review
Letters, 86:5188--5191, 2001), a universal quantum computation scheme with
promising physical implementations, can be efficiently simulated by a
randomized algorithm if its quantum resource is derived from a small-treewidth
graph.Comment: 7 figure
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