2,415 research outputs found
Abelian Higgs Hair for AdS-Schwarzschild Black Hole
We show that the Abelian Higgs field equations in the background of the four
dimensional AdS-Schwarzschild black hole have a vortex line solution. This
solution, which has axial symmetry, is a generalization of the AdS spacetime
Nielsen-Olesen string. By a numerical study of the field equations, we show
that black hole could support the Abelian Higgs field as its Abelian hair.
Also, we conside the self gravity of the Abelian Higgs field both in the pure
AdS spacetime and AdS-Schwarzschild black hole background and show that the
effect of string as a black hole hair is to induce a deficit angle in the
AdS-Schwarzschild black hole.Comment: 19 pages, 33 figure
Laser Phase and Frequency Stabilization Using Atomic Coherence
We present a novel and simple method of stabilizing the laser phase and
frequency by polarization spectroscopy of an atomic vapor. In analogy to the
Pound-Drever-Hall method, which uses a cavity as a memory of the laser phase,
this method uses atomic coherence (dipole oscillations) as a phase memory of
the transmitting laser field. A preliminary experiment using a distributed
feedback laser diode and a rubidium vapor cell demonstrates a
shot-noise-limited laser linewidth reduction (from 2 MHz to 20 kHz). This
method would improve the performance of gas-cell-based optical atomic clocks
and magnetometers and facilitate laser-cooling experiments using narrow
transitions.Comment: 7 pages, 6 figures, appendix on the derivation of Eq.(3) (transfer
function for a polarization-spectroscopy-based frequency discriminator) has
been adde
Thermal-Fluid Flow Transport Phenomenon over Slot-Perforated Flat Plates Placed in Narrow Channel
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76151/1/AIAA-25872-119.pd
Coronary arterial dynamics computation with medical-image-based time-dependent anatomical models and element-based zero-stress state estimates
We propose a method for coronary arterial dynamics computation with medical-image-based time-dependent anatomical models. The objective is to improve the computational analysis of coronary arteries for better understanding of the links between the atherosclerosis development and mechanical stimuli such as endothelial wall shear stress and structural stress in the arterial wall. The method has two components. The first one is element-based zero-stress (ZS) state estimation, which is an alternative to prestress calculation. The second one is a "mixed ZS state" approach, where the ZS states for different elements in the structural mechanics mesh are estimated with reference configurations based on medical images coming from different instants within the cardiac cycle. We demonstrate the robustness of the method in a patient-specific coronary arterial dynamics computation where the motion of a thin strip along the arterial surface and two cut surfaces at the arterial ends is specified to match the motion extracted from the medical images. © 2014 The Author(s)
Abelian Higgs Hair for a Static Charged Black String
We study the problem of vortex solutions in the background of an electrically
charged black string. We show numerically that the Abelian Higgs field
equations in the background of a four-dimensional black string have vortex
solutions. These solutions which have axial symmetry, show that the black
string can support the Abelian Higgs field as hair. This situation holds also
in the case of the extremal black string. We also consider the self-gravity of
the Abelian Higgs field and show that the effect of the vortex is to induce a
deficit angle in the metric under consideration.Comment: REVTEX4, 12 pages, 6 figures, The version to be appeared in Phys.
Rev.
Do naked singularities generically occur in generalized theories of gravity?
A new mechanism for causing naked singularities is found in an effective
superstring theory. We investigate the gravitational collapse in a spherically
symmetric Einstein-Maxwell-dilaton system in the presence of a pure
cosmological constant "potential", where the system has no static black hole
solution. We show that once gravitational collapse occurs in the system, naked
singularities necessarily appear in the sense that the field equations break
down in the domain of outer communications. This suggests that in generalized
theories of gravity, the non-minimally coupled fields generically cause naked
singularities in the process of gravitational collapse if the system has no
static or stationary black hole solution.Comment: 4 pages including 2 eps figures, to be published in Physical Review
Letter
Systematic study of the decay rates of antiprotonic helium states
A systematic study of the decay rates of antiprotonic helium (\pbhef and
\pbhet) at CERN AD (Antiproton Decelerator) has been made by a laser
spectroscopic method. The decay rates of some of its short-lived states, namely
those for which the Auger rates are much larger than
their radiative decay rates ( s),
were determined from the time distributions of the antiproton annihilation
signals induced by laser beams, and the widths of the atomic resonance lines.
The magnitude of the decay rates, especially their relation with the transition
multipolarity, is discussed and compared with theoretical calculations.Comment: 6 pages, 5 figures, and 1 tabl
Perturbations of global monopoles as a black hole's hair
We study the stability of a spherically symmetric black hole with a global
monopole hair. Asymptotically the spacetime is flat but has a deficit solid
angle which depends on the vacuum expectation value of the scalar field. When
the vacuum expectation value is larger than a certain critical value, this
spacetime has a cosmological event horizon. We investigate the stability of
these solutions against the spherical and polar perturbations and confirm that
the global monopole hair is stable in both cases. Although we consider some
particular modes in the polar case, our analysis suggests the conservation of
the "topological charge" in the presence of the event horizons and violation of
black hole no-hair conjecture in asymptotically non-flat spacetime.Comment: 11 pages, 2 figures, some descriptions were improve
Internal structure of Skyrme black hole
We consider the internal structure of the Skyrme black hole under a static
and spherically symmetric ansatz. $@u8(Be concentrate on solutions with the
node number one and with the "winding" number zero, where there exist two
solutions for each horizon radius; one solution is stable and the other is
unstable against linear perturbation. We find that a generic solution exhibits
an oscillating behavior near the sigularity, as similar to a solution in the
Einstein-Yang-Mills (EYM) system, independently to stability of the solution.
Comparing it with that in the EYM system, this oscillation becomes mild because
of the mass term of the Skyrme field. We also find Schwarzschild-like
exceptional solutions where no oscillating behavior is seen. Contrary to the
EYM system where there is one such solution branch if the node number is fixed,
there are two branches corresponding to the stable and the unstable ones.Comment: 5 pages, 4 figures, some contents adde
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