1,998 research outputs found
Three-dimensional Black Holes and Liouville Field Theory
A quantization of (2+1)-dimensional gravity with negative cosmological
constant is presented and quantum aspects of the (2+1)-dimensional black holes
are studied thereby. The quantization consists of two procedures. One is
related with quantization of the asymptotic Virasoro symmetry. A notion of the
Virasoro deformation of 3-geometry is introduced. For a given black hole, the
deformation of the exterior of the outer horizon is identified with a product
of appropriate coadjoint orbits of the Virasoro groups .
Its quantization provides unitary irreducible representations of the Virasoro
algebra, in which state of the black hole becomes primary. To make the
quantization complete, holonomies, the global degrees of freedom, are taken
into account. By an identification of these topological operators with zero
modes of the Liouville field, the aforementioned unitary representations
reveal, as far as , as the Hilbert space of this two-dimensional
conformal field theory. This conformal field theory, living on the cylinder at
infinity of the black hole and having continuous spectrums, can recognize the
outer horizon only as a it one-dimensional object in and
realize it as insertions of the corresponding vertex operator. Therefore it can
not be a conformal field theory on the horizon. Two possible descriptions of
the horizon conformal field theory are proposed.Comment: 39 pages, LaTeX, 8 figures are added. Section 4.3 is revised and
enlarged to include the case of conical singularities. Several typos are
corrected. References are adde
Observations of gravity waves in the mesosphere with the MU radar
Wind motions were observed at 60 to 90 km altitudes with the MU radar during daylight hours (0800 to 1600 LT) from 13 to 31 October 1986. Quasi-monochromatic gravity waves were evident on 16 of the 19 days of observations. They were characterized by typical vertical wavelength of 5 to 15 km and intrinsic periods centered at about 9 hours. The propagation direction of the gravity waves, determined by the gravity wave dispersion relation, was mostly equatorward. The vertical wave number spectra of the horizontal components of the mesoscale wind fluctuations are explained well by saturated gravity wave theory. The frequency spectrum of vertical wind component has a slope of + 1/3, while the oblique spectra have a slope of -5/3 up to 4 x 10(-3) (c/s); these agree fairly well with model gravity wave spectra. Doppler shift effects on the frequency spectra are recognized at higher frequencies. Upward flux was determined of horizontal momentum flux induced by waves with periods from 10 min to 8 hours, and westward and northward body forces of 5.1 and 4.0 m/s/day, were estimated respectively
Relationships between a roller and a dynamic pressure distribution in circular hydraulic jumps
We investigated numerically the relation between a roller and the pressure
distribution to clarify the dynamics of the roller in circular hydraulic jumps.
We found that a roller which characterizes a type II jump is associated with
two high pressure regions after the jump, while a type I jump (without the
roller) is associated with only one high pressure region. Our numerical results
show that building up an appropriate pressure field is essential for a roller.Comment: 10 pages, 7 PS files. To appear in PR
Note on Triangle Anomalies and Assignment of Singlet in 331-like Model
It is pointed out that in the like model which uses both fundamental
and complex conjugate representations for an assignment of the representations
to the left-handed quarks and the scalar representation to their corresponding
right-handed counterparts, the nature of the scalar should be taken into
account in order to make the fermion triangle anomalies in the theory
anomaly-free, i.e. renormalizable in a sense with no anomalies, even after the
spontaneous symmetry breaking.Comment: 8 page no figures, acknowledgments adde
An FFAG Transport Line for the PAMELA Project
The PAMELA project to design an accelerator for
hadron therapy using non-scaling Fixed Field Alternating
Gradient (NS-FFAG) magnets requires a transport line
and gantry to take the beam to the patient. The NS-FFAG
principle offers the possibility of a gantry much smaller,
lighter and cheaper than conventional designs, with the
added ability to accept a wide range of fast changing
energies. This paper will build on previous work to
investigate a transport line which could be used for the
PAMELA project. The design is presented along with a
study and optimisation of its acceptance
Physarum boats: If plasmodium sailed it would never leave a port
Plasmodium of \emph{Physarum polycephalum} is a single huge (visible by naked
eye) cell with myriad of nuclei. The plasmodium is a promising substrate for
non-classical, nature-inspired, computing devices. It is capable for
approximation of shortest path, computation of planar proximity graphs and
plane tessellations, primitive memory and decision-making. The unique
properties of the plasmodium make it an ideal candidate for a role of amorphous
biological robots with massive parallel information processing and distributed
inputs and outputs. We show that when adhered to light-weight object resting on
a water surface the plasmodium can propel the object by oscillating its
protoplasmic pseudopodia. In experimental laboratory conditions and
computational experiments we study phenomenology of the plasmodium-floater
system, and possible mechanisms of controlling motion of objects propelled by
on board plasmodium
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