8,778 research outputs found
Imide and isatin derivatives as β-lactam mimics of β-lactam antibiotics
Activated γ-lactams, which are derivatives of succinimide, phthalimide and isatin with suitable
elements of molecular recognition, have been synthesised as mimics of the ß-lactam antibiotics
and their chemical and biological reactivity determined
Complete Integrability of Geodesic Motion in General Kerr-NUT-AdS Spacetimes
We explicitly exhibit n-1 constants of motion for geodesics in the general
D-dimensional Kerr-NUT-AdS rotating black hole spacetime, arising from
contractions of even powers of the 2-form obtained by contracting the geodesic
velocity with the dual of the contraction of the velocity with the
(D-2)-dimensional Killing-Yano tensor. These constants of motion are
functionally independent of each other and of the D-n+1 constants of motion
that arise from the metric and the D-n = [(D+1)/2] Killing vectors, making a
total of D independent constants of motion in all dimensions D. The Poisson
brackets of all pairs of these D constants are zero, so geodesic motion in
these spacetimes is completely integrable.Comment: 4 pages. We have now found that the geodesic motion is not just
integrable, but completely integrabl
Mesoscopic phase statistics of diffuse ultrasound in dynamic matter
Temporal fluctuations in the phase of waves transmitted through a dynamic,
strongly scattering, mesoscopic sample are investigated using ultrasonic waves,
and compared with theoretical predictions based on circular Gaussian
statistics. The fundamental role of phase in Diffusing Acoustic Wave
Spectroscopy is revealed, and phase statistics are also shown to provide a
sensitive and accurate way to probe scatterer motions at both short and long
time scales.Comment: 4 pages, 4 figures, submitted to Physical Review Letter
Proof of the Generalized Second Law for Quasistationary Semiclassical Black Holes
A simple direct explicit proof of the generalized second law of black hole
thermodynamics is given for a quasistationary semiclassical black hole.Comment: 12 pages, LaTeX, report Alberta-Thy-10-93 (revision of paper in
response to Phys. Rev. Lett. referees' comments, which suffered a series of
long delays
Radiation of Charged Particles by Charged Black Hole
The probability of a charged particle production by the electric field of a
charged black hole depends essentially on the particle energy. This probability
is found in the nonrelativistic and ultrarelativistic limits. The range of
values for the mass and charge of a black hole is indicated where the discussed
mechanism of radiation is dominating over the Hawking one.Comment: 10 pages, latex, 4 ps-figure
Constants of Geodesic Motion in Higher-Dimensional Black-Hole Spacetimes
In [arXiv:hep-th/0611083] we announced the complete integrability of geodesic
motion in the general higher-dimensional rotating black-hole spacetimes. In the
present paper we prove all the necessary steps leading to this conclusion. In
particular, we demonstrate the independence of the constants of motion and the
fact that they Poisson commute. The relation to a different set of constants of
motion constructed in [arXiv:hep-th/0612029] is also briefly discussed.Comment: 8 pages, no figure
Nonthermal radiation of rotating black holes
Nonthermal radiation of a Kerr black hole is considered as tunneling of
created particles through an effective Dirac gap. In the leading semiclassical
approximation this approach is applicable to bosons as well. Our semiclassical
results for photons and gravitons do not contradict those obtained previously.
For neutrinos the result of our accurate quantum mechanical calculation is
about two times larger than the previous one.Comment: 10 pages, 2 figures; 2 references added, few typos correcte
Solving the degeneracy of the lepton-flavor mixing angle theta_atm by the T2KK two detector neutrino oscillation experiment
If the atmospheric neutrino oscillation amplitude, sin^2 2theta_atm is not
maximal, there is a two fold ambiguity in the neutrino parameter space: sin^2
theta_atm>0.5 or sin^2 theta_atm<0.5. In this article, we study the impact of
this degeneracy, the so-called octant degeneracy, on the T2KK experiment, which
is a proposed extension of the T2K (Tokai-to-Kaimoka) neutrino oscillation
experiment with an additional water cherenkov detector placed in Korea. We find
that the degeneracy between sin^2 theta_atm= 0.40 and 0.60 can be resolved at
the 3sigma level for sin^2 2theta_rct>0.12 (0.08) for the optimal combination
of a 3.0^circ off-axis beam (OAB) at SK (L=295km) and a 0.5^circ OAB at
L=1000km with a far detector of 100kton volume, after 5 years of exposure with
1.0(5.0) time 10^21 POT/year, if the hierarchy is normal. We also study the
influence of the octant degeneracy on the capability of T2KK experiment to
determine the mass hierarchy and the leptonic CP phase. The capability of
rejecting the wrong mass hierarchy grows with increasing sin^2 theta_atm when
the hierarchy is normal, whereas it is rather insensitive to sin^2 theta_atm
for the inverted hierarchy. We also find that the 1sigma allowed region of the
CP phase is not affected significantly even when the octant degeneracy is not
resolved. All our results are obtained for the 22.5 kton Super-Kamiokande as a
near detector and without an anti-neutrino beam.Comment: 23 pages, 9 figure
Improved Approximations for Fermion Pair Production in Inhomogeneous Electric Fields
Reformulating the instantons in a complex plane for tunneling or transmitting
states, we calculate the pair-production rate of charged fermions in a
spatially localized electric field, illustrated by the Sauter electric field
E_0 sech^2 (z/L), and in a temporally localized electric field such as E_0
sech^2 (t/T). The integration of the quadratic part of WKB instanton actions
over the frequency and transverse momentum leads to the pair-production rate
obtained by the worldline instanton method, including the prefactor, of Phys.
Rev. D72, 105004 (2005) and D73, 065028 (2006). It is further shown that the
WKB instanton action plus the next-to-leading order contribution in spinor QED
equals the WKB instanton action in scalar QED, thus justifying why the WKB
instanton in scalar QED can work for the pair production of fermions. Finally
we obtain the pair-production rate in a spatially localized electric field
together with a constant magnetic field in the same direction.Comment: RevTex, 12 pages, two figures; replaced by the version accepted in
Phys. Rev.
Complex Instantons and Charged Rotating Black Hole Pair Creation
We consider the general process of pair-creation of charged rotating black
holes. We find that instantons which describe this process are necessarily
complex due to regularity requirements. However their associated probabilities
are real, and fully consistent with the interpretation that the entropy of a
charged rotating black hole is the logarithm of the number of its quantum
states.Comment: 11 pages, 1 figure, Latex, text shortened with only minor changes in
content, accepted for Phys Rev Letter
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