172 research outputs found
Remarks on Hawking radiation as tunneling from the BTZ black holes
Hawking radiation viewed as a semiclassical tunneling process from the event
horizon of the (2 + 1)-dimensional rotating BTZ black hole is carefully
reexamined by taking into account not only the energy conservation but also the
conservation of angular momentum when the effect of the emitted particle's
self-gravitation is incorporated. In contrast to previous analysis of this
issue in the literature, our result obtained here fits well to the
Kraus-Parikh-Wilczek's universal conclusion without any modification to the
Bekenstein-Hawking area-entropy formulae of the BTZ black hole.Comment: 12pages, no figure, use JHEP3.cls. Version better than published one
in JHE
"Charged" Particle's Tunneling from Rotating Black Holes
The behavior of a scalar field theory near the event horizon in a rotating
black hole background can be effectively described by a two dimensional field
theory in a gauge field background. Based on this fact, we proposal that the
quantum tunneling from rotating black hole can be treated as "charged"
particle' s tunneling process in its effectively two dimensional metric. Using
this viewpoint and considering the corresponding "gauge charge" conservation,
we calculate the non-thermal tunneling rate of Kerr black hole and Myers-Perry
black hole, and results are consistent with Parikh-Wilczek's original result
for spherically symmetric black holes. Especially for Myers-Perry black hole
which has multi-rotation parameters, our calculation fills in the gap existing
in the literature applying Parikh-Wilczek's tunneling method to various types
black holes. Our derivation further illuminates the essential role of effective
gauge symmetry in Hawking radiation from rotating black holes.Comment: 15 pages, no figure; any comments are welcome
Entropy spectrum of a Kerr anti-de Sitter black hole
The entropy spectrum of a spherically symmetric black hole was derived
without the quasinormal modes in the work of Majhi and Vagenas. Extending this
work to rotating black holes, we quantize the entropy and the horizon area of a
Kerr anti-de Sitter black hole by two methods. The spectra of entropy and area
are obtained via the Bohr-Sommerfeld quantization rule and the adiabatic
invariance in the first way. By addressing the wave function of emitted
(absorbed) particles, the entropy and the area are quantized in the second one.
Both results show that the entropy and the area spectra are equally spaced.Comment: Accepted for publication in The European Physical Journal C, Volume
72, Issue
Phase separating binary fluids under oscillatory shear
We apply lattice Boltzmann methods to study the segregation of binary fluid
mixtures under oscillatory shear flow in two dimensions. The algorithm allows
to simulate systems whose dynamics is described by the Navier-Stokes and the
convection-diffusion equations. The interplay between several time scales
produces a rich and complex phenomenology. We investigate the effects of
different oscillation frequencies and viscosities on the morphology of the
phase separating domains. We find that at high frequencies the evolution is
almost isotropic with growth exponents 2/3 and 1/3 in the inertial (low
viscosity) and diffusive (high viscosity) regimes, respectively. When the
period of the applied shear flow becomes of the same order of the relaxation
time of the shear velocity profile, anisotropic effects are clearly
observable. In correspondence with non-linear patterns for the velocity
profiles, we find configurations where lamellar order close to the walls
coexists with isotropic domains in the middle of the system. For particular
values of frequency and viscosity it can also happen that the convective
effects induced by the oscillations cause an interruption or a slowing of the
segregation process, as found in some experiments. Finally, at very low
frequencies, the morphology of domains is characterized by lamellar order
everywhere in the system resembling what happens in the case with steady shear.Comment: 1 table and 12 figures in .gif forma
Spectroscopy of the Einstein-Maxwell-Dilaton-Axion black hole
The entropy spectrum of a spherically symmetric black hole was derived via
the Bohr-Sommerfeld quantization rule in Majhi and Vagenas's work. Extending
this work to charged and rotating black holes, we quantize the horizon area and
the entropy of an Einstein-Maxwell-Dilaton-Axion (EMDA) black hole via the
Bohr-Sommerfeld quantization rule and the adiabatic invariance. The result
shows the area spectrum and the entropy spectrum are respectively equally
spaced and independent on the parameters of the black hole.Comment: 9 page
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
- …