3,537 research outputs found
First law of black hole mechanics in Einstein-Maxwell and Einstein-Yang-Mills theories
The first law of black hole mechanics is derived from the Einstein-Maxwell
(EM) Lagrangian by comparing two infinitesimally nearby stationary black holes.
With similar arguments, the first law of black hole mechanics in
Einstein-Yang-Mills (EYM) theory is also derived.Comment: Modified version, major changes made in the introduction. 14 pages,
no figur
A stability version of H\"older's inequality
We present a stability version of H\"older's inequality, incorporating an
extra term that measures the deviation from equality. Applications are given.Comment: Journal of Mathematical Analysis and Applications, Volume 343, Issue
2, Pages 842-852. This version differs from the published one in that it
contains a new reference, and a trivial improvement of Corollary 3.2. fo
Aspects of the Screening Length and Drag Force in Two Alternative Gravity Duals of the Quark-gluon Plasma
We compute the screening length of mesons with different angular momentum
from two gravity dual theories. Both the asymptotically and
Sakai-Sugimoto metrics are considered in the calculations. Using the dual
description of the quark as a classical string ending on the probe brane, we
obtain the interacting potential between the heavy quark and antiquark after
rotating the background metric. The result shows that the screening length of
mesons with different is well fit to . The constant is
determined for by taking advantage of numerical techniques. Finally,
we calculate the drag force and relaxation times from the Sakai-Sugimoto metric
and compare with the ones obtained in the . The application of our
result to charmonium and bottomonium at RHIC and LHC is briefly discussed.Comment: 18 pages, 6 figures, 2 tables, version to appear in JHEP,
acknowledgment adde
Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows
In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck
transport model, effect of the momentum dependence of nuclear symmetry
potential on nuclear transverse and elliptic flows in the neutron-rich reaction
Sn+Sn at a beam energy of 400 MeV/nucleon is studied. We find
that the momentum dependence of nuclear symmetry potential affects the rapidity
distribution of the free neutron to proton ratio, the neutron and the proton
transverse flows as a function of rapidity. The momentum dependence of nuclear
symmetry potential affects the neutron-proton differential transverse flow more
evidently than the difference of neutron and proton transverse flows as well as
the difference of proton and neutron elliptic flows. It is thus better to probe
the symmetry energy by using the difference of neutron and proton flows since
the momentum dependence of nuclear symmetry potential is still an open
question. And it is better to probe the momentum dependence of nuclear symmetry
potential by using the neutron-proton differential transverse flow and the
rapidity distribution of the free neutron to proton ratio.Comment: 6 pages, 6 figures, to be published by EPJ
Is the `Finite Bias Anomaly' in planar GaAs-Superconductor junctons caused by point-contact like structures?
We correlate transmission electron microscope (TEM) pictures of
superconducting In contacts to an AlGaAs/GaAs heterojunction with differential
conductance spectroscopy performed on the same heterojunction. Metals deposited
onto a (100) AlGaAs/GaAs heterostructure do not form planar contacts but,
during thermal annealing, grow down into the heterostructure along
crystallographic planes in pyramid-like `point contacts'. Random surface
nucleation and growth gives rise to a different interface transmission for each
superconducting point contact. Samples annealed for different times, and
therefore having different contact geometry, show variations in
characteristic of ballistic transport of Cooper pairs, wave interference
between different point emitters, and different types of weak localization
corrections to Giaever tunneling. We give a possible mechanism whereby the
`finite bias anomaly' of Poirier et al. (Phys. Rev. Lett., {\bf 79}, 2105
(1997)), also observed in these samples, can arise by adding the conductance of
independent superconducting point emitters in parallel
Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion
The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER)
spectra of spheroidal biological cell suspensions with an intrinsic dispersion
in the constituent dielectric constants are investigated. By means of the
spectral representation method, we express analytically the characteristic
frequencies and dispersion strengths both for the effective dielectric constant
and the Clausius-Mossotti factor (CMF). We identify four and six characteristic
frequencies for the effective dielectric spectra and CMF respectively, all of
them being dependent on the depolarization factor (or the cell shape). The
analytical results allow us to examine the effects of the cell shape, the
dispersion strength and the intrinsic frequency on the dielectric dispersion,
DEP and ER spectra. Furthermore, we include the local-field effects due to the
mutual interactions between cells in a dense suspension, and study the
dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.
Metallic charge stripes in cuprates
Some recent evidence for the existence of dynamic, metallic stripes in the
214-family of cuprates is reviewed. The mechanism of stripe pinning is
considered, and changes in the charge density within stripes between the pinned
and dynamic phases is discussed. From a purely experimental perspective,
dynamic charge stripes are fully compatible with nodal ``quasiparticles'' and
other electronic properties common to all superconducting cuprates.Comment: 4 pp., for proceedings of M2S-Ri
Observation of diffractive orbits in the spectrum of excited NO in a magnetic field
We investigate the experimental spectra of excited NO molecules in the
diamagnetic regime and develop a quantitative semiclassical framework to
account for the results. We show the dynamics can be interpreted in terms of
classical orbits provided that in addition to the geometric orbits, diffractive
effects are appropriately taken into account. We also show how individual
orbits can be extracted from the experimental signal and use this procedure to
reveal the first experimental manifestation of inelastic diffractive orbits.Comment: 4 fig
Dominance of gauge artifact in the consistency relation for the primordial bispectrum
The conventional cosmological perturbation theory has been performed under
the assumption that we know the whole spatial region of the universe with
infinite volume. This is, however, not the case in the actual observations
because observable portion of the universe is limited. To give a theoretical
prediction to the observable fluctuations, gauge-invariant observables should
be composed of the information in our local observable universe with finite
volume. From this point of view, we reexamine the primordial non-Gaussianity in
single field models, focusing on the bispectrum in the squeezed limit. A
conventional prediction states that the bispectrum in this limit is related to
the power spectrum through the so-called consistency relation. However, it
turns out that, if we adopt a genuine gauge invariant variable which is
naturally composed purely of the information in our local universe, the leading
term for the bispectrum in the squeezed limit predicted by the consistency
relation vanishes.Comment: 12 pages; v2: accepted version in JCA
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