4,962 research outputs found
Spacetime Defects: von K\'arm\'an vortex street like configurations
A special arrangement of spinning strings with dislocations similar to a von
K\'arm\'an vortex street is studied. We numerically solve the geodesic
equations for the special case of a test particle moving along twoinfinite rows
of pure dislocations and also discuss the case of pure spinning defects.Comment: 9 pages, 2figures, CQG in pres
On the gravitational field of static and stationary axial symmetric bodies with multi-polar structure
We give a physical interpretation to the multi-polar Erez-Rozen-Quevedo
solution of the Einstein Equations in terms of bars. We find that each
multi-pole correspond to the Newtonian potential of a bar with linear density
proportional to a Legendre Polynomial. We use this fact to find an integral
representation of the function. These integral representations are
used in the context of the inverse scattering method to find solutions
associated to one or more rotating bodies each one with their own multi-polar
structure.Comment: To be published in Classical and Quantum Gravit
The ambivalent shadow of the pre-Wilsonian rise of international law
The generation of American international lawyers who founded the American Society of International Law in 1906 and nurtured the soil for what has been retrospectively called a “moralistic legalistic approach to international relations” remains little studied. A survey of the rise of international legal literature in the U.S. from the mid-19th century to the eve of the Great War serves as a backdrop to the examination of the boosting effect on international law of the Spanish American War in 1898. An examination of the Insular Cases before the US Supreme Court is then accompanied by the analysis of a number of influential factors behind the pre-war rise of international law in the U.S. The work concludes with an examination of the rise of natural law doctrines in international law during the interwar period and the critiques addressed.by the realist founders of the field of “international relations” to the “moralistic legalistic approach to international relation
Area spectra of the rotating BTZ black hole from quasinormal modes
Following Bekenstein's suggestion that the horizon area of a black hole
should be quantized, the discrete spectrum of the horizon area has been
investigated in various ways. By considering the quasinormal mode of a black
hole, we obtain the transition frequency of the black hole, analogous to the
case of a hydrogen atom, in the semiclassical limit. According to Bohr's
correspondence principle, this transition frequency at large quantum number is
equal to classical oscillation frequency. For the corresponding classical
system of periodic motion with this oscillation frequency, an action variable
is identified and quantized via Bohr-Sommerfeld quantization, from which the
quantized spectrum of the horizon area is obtained. This method can be applied
for black holes with discrete quasinormal modes. As an example, we apply the
method for the both non-rotating and rotating BTZ black holes and obtain that
the spectrum of the horizon area is equally spaced and independent of the
cosmological constant for both cases
On the ground-state properties of antiferromagnetic half-integer spin chains with long-range interactions
The Lieb-Shultz-Mattis theorem is extended to Heisenberg chains with
long-range interactions. We prove that the half-integer spin chain has no gap,
if it possesses unique ground state and the exchange decays faster than the
inverse-square of distance between spins. The results can be extended to a wide
class of one-dimensional models.Comment: 3 pages, RevTeX
A review of the decoherent histories approach to the arrival time problem in quantum theory
We review recent progress in understanding the arrival time problem in
quantum mechanics, from the point of view of the decoherent histories approach
to quantum theory. We begin by discussing the arrival time problem, focussing
in particular on the role of the probability current in the expected classical
solution. After a brief introduction to decoherent histories we review the use
of complex potentials in the construction of appropriate class operators. We
then discuss the arrival time problem for a particle coupled to an environment,
and review how the arrival time probability can be expressed in terms of a POVM
in this case. We turn finally to the question of decoherence of the
corresponding histories, and we show that this can be achieved for simple
states in the case of a free particle, and for general states for a particle
coupled to an environment.Comment: 10 pages. To appear in DICE 2010 conference proceeding
Ultra-High Energy Neutrino Fluxes: New Constraints and Implications
We apply new upper limits on neutrino fluxes and the diffuse extragalactic
component of the GeV gamma-ray flux to various scenarios for ultra high energy
cosmic rays and neutrinos. As a result we find that extra-galactic top-down
sources can not contribute significantly to the observed flux of highest energy
cosmic rays. The Z-burst mechanism where ultra-high energy neutrinos produce
cosmic rays via interactions with relic neutrinos is practically ruled out if
cosmological limits on neutrino mass and clustering apply.Comment: 10 revtex pages, 9 postscript figure
Are solar neutrino oscillations robust?
The robustness of the large mixing angle (LMA) oscillation (OSC)
interpretation of the solar neutrino data is considered in a more general
framework where non-standard neutrino interactions (NSI) are present. Such
interactions may be regarded as a generic feature of models of neutrino mass.
The 766.3 ton-yr data sample of the KamLAND collaboration are included in the
analysis, paying attention to the background from the reaction ^13C(\alpha,n)
^16O. Similarly, the latest solar neutrino fluxes from the SNO collaboration
are included. In addition to the solution which holds in the absence of NSI
(LMA-I) there is a 'dark-side' solution (LMA-D) with sin^2 theta_Sol = 0.70,
essentially degenerate with the former, and another light-side solution (LMA-0)
allowed only at 97% CL. More precise KamLAND reactor measurements will not
resolve the ambiguity in the determination of the solar neutrino mixing angle
theta_Sol, as they are expected to constrain mainly Delta m^2. We comment on
the complementary role of atmospheric, laboratory (e.g. CHARM) and future solar
neutrino experiments in lifting the degeneracy between the LMA-I and LMA-D
solutions. In particular, we show how the LMA-D solution induced by the
simplest NSI between neutrinos and down-type-quarks-only is in conflict with
the combination of current atmospheric data and data of the CHARM experiment.
We also mention that establishing the issue of robustness of the oscillation
picture in the most general case will require further experiments, such as
those involving low energy solar neutrinos.Comment: 13 pages, 6 figures; Final version to appear in JHE
Nonsingular and accelerated expanding universe from effective Yang-Mills theory
The energy-momentum tensor coming from one-parameter effective Yang- Mills
theory is here used to describe the matter-energy content of the homogeneous
and isotropic Friedmann cosmology in its early stages. The behavior of all
solutions is examined. Particularly, it is shown that only solutions
corresponding to an open model allow the universe to evolve into an accelerated
expansion. This result appears as a possible mechanism for an inflationary
phase produced by a vector field. Further, depending on the value of some
parameters characterizing the system, the resulting models are classified as
singular or nonsingular.Comment: 15 pages, 7 figures, some discussions were simplified and new remarks
were introduce
The Case against Copyright: A Comparative Institutional Analysis of Intellectual Property Regimes
- …