369 research outputs found
Low energy effective theory on a regularized brane in six-dimensional flux compactifications
Conical brane singularities in six-dimensional flux compactification models
can be resolved by introducing cylindrical codimension-one branes with regular
caps instead of 3-branes (a la Kaluza-Klein braneworlds with fluxes). In this
paper, we consider such a regularized braneworld with axial symmetry in
six-dimensional Einstein-Maxwell theory. We derive a low energy effective
theory on the regularized brane by employing the gradient expansion approach,
and show that standard four-dimensional Einstein gravity is recovered at low
energies. Our effective equations extend to the nonlinear gravity regime,
implying that conventional cosmology can be reproduced in the regularized
braneworld.Comment: 11 pages, minor corrections, accepted for publication in Physical
Review
High-energy effective theory for a bulk brane
We derive an effective theory describing the physics of a bulk brane in the
context of the RS1 model. This theory goes beyond the usual low energy
effective theory in that it describes the regime where the bulk brane has a
large velocity and the radion can change rapidly. We achieve this by
concentrating on the region where the distance between the orbifold planes is
small in comparison to the AdS length scale. Consequently our effective theory
will describe the physics shortly before a bulk/boundary or boundary/boundary
brane collision. We study the cosmological solutions and find that, at large
velocities, the bulk brane decouples from the matter on the boundary branes, a
result which remains true for cosmological perturbations.Comment: Updated version as published in PR
The final fate of instability of Reissner-Nordstr\"om-anti-de Sitter black holes by charged complex scalar fields
We investigate instability of 4-dimensional Reissner-Nordstr\"om-anti-de
Sitter (RN-AdS) black holes with various topologies by charged scalar field
perturbations. We numerically find that the RN-AdS black holes become
unstable against the linear perturbations below a critical temperature. It is
analytically shown that charge extraction from the black holes occurs during
the unstable evolution. To explore the end state of the instability, we
perturbatively construct static black hole solutions with the scalar hair near
the critical temperature. It is numerically found that the entropy of the
hairly black hole is always larger than the one of the unstable RN-AdS
black hole in the microcanonical ensemble. Our results support the speculation
that the black hole with charged scalar hair always appears as the final fate
of the instability of the RN-AdS black hole.Comment: 9 pages, 4 figures. To appear in PR
THE ANALYSIS OF RACE PACING IN ELITE COMPETITIVE LONG-DISTANCE SPEED SKATING
The purpose of this study was to investigate the characteristics of racing pattern adopted by elite male speed skaters in official 5000m race. Twenty-four male skaters, who participated at the World Single Distances Speed Skating Championships 2008, were recorded using video camera (60Hz). The top group (top12 ranked skaters) was significantly faster than the 2nd group (13th to 24th ranked skaters) from 350m line to the finishing line (
Gravity is controlled by cosmological constant
We discuss a Randall-Sundrum-type two D-braneworld model in which D-branes
possess different values of the tensions from those of the charges, and derive
an effective gravitational equation on the branes. As a consequence, the
Einstein-Maxwell theory is realized together with the non-zero cosmological
constant. Here an interesting point is that the effective gravitational
constant is proportional to the cosmological constant. If the distance between
two D-branes is appropriately tuned, the cosmological constant can have a
consistent value with the current observations. From this result we see that,
in our model, the presence of the cosmological constant is naturally explained
by the presence of the effective gravitational coupling of the Maxwell field on
the D-brane.Comment: 10 page
High-energy effective theory for orbifold branes
We derive an effective theory on the orbifold branes of the Randall-Sundrum 1
(RS1) braneworld scenario in the presence of a bulk brane. We concentrate on
the regime where the three branes are close and consider a scenario where the
bulk brane collides with one of the orbifold branes. This theory allows us to
understand the corrections to a low-energy approach due to the presence of
higher velocity terms, coming from the Kaluza-Klein modes. We consider the
evolution of gravitational waves on a cosmological background and find that,
within the large velocity limit, the boundary branes recover a purely
four-dimensional behavior.Comment: 4 pages, accepted for publication in Phys. Rev.
Wastewater Management Efficiency and Determinant Factors in the Chinese Industrial Sector from 2004 to 2014
This study analyzes industrial wastewater management efficiency using a Chinese provincial dataset from 2004 to 2014. The weighted Russell directional distance model is used to evaluate the efficiency of management practices. Determinants analysis was conducted based on governmental policy, pollution abatement, and market factors to identify the main drivers of industrial wastewater management efficiency in China. The results indicate that the wastewater management efficiency improved in the eastern and central regions. However, there is a significant efficiency gap between provinces in the western region. Moreover, the main determinants of wastewater management efficiency differ among regions and pollutants
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