407 research outputs found
Linear Sigma Models of H and KK Monopoles
We propose a gauged linear sigma model of k H-monopoles. We also consider the
T-dual of this model describing KK-monopoles and clarify the meaning of
"winding coordinate" studied recently in hep-th/0507204.Comment: 13 pages, lanlmac; V3:added argument on the nature of disk instanto
Black String Perturbations in RS1 Model
We present a general formalism for black string perturbations in
Randall-Sundrum 1 model (RS1). First, we derive the master equation for the
electric part of the Weyl tensor . Solving the master equation
using the gradient expansion method, we give the effective Teukolsky equation
on the brane at low energy. It is useful to estimate gravitational waves
emitted by perturbed rotating black strings. We also argue the effect of the
Gregory-Laflamme instability on the brane using our formalism.Comment: 14 pages, Based on a talk presented at ACRGR4, the 4th Australasian
Conference on General Relativity and Gravitation, Monash University,
Melbourne, January 2004. To appear in the proceedings, in General Relativity
and Gravitatio
Branes, Instantons, And Taub-NUT Spaces
ALE and Taub-NUT (or ALF) hyper-Kahler four-manifolds can be naturally
constructed as hyper-Kahler quotients. In the ALE case, this construction has
long been understood in terms of D-branes; here we give a D-brane derivation in
the Taub-NUT case. Likewise, instantons on ALE spaces and on Taub-NUT spaces
have ADHM-like constructions related to hyper-Kahler quotients. Here we refine
the analysis in the Taub-NUT case by making use of a D-brane probe, and give an
application to M-theory.Comment: 63 p
Inequalities in child development at school entry: a repeated cross-sectional analysis of the Australian Early Development Census 2009–2018
Background: Australia is the only developed country to consistently undertake a developmental census of its children nationwide. The repeated collection of the Australian Early Development Census (AEDC) has provided an unprecedented opportunity to examine the prevalence of developmental vulnerability across Australia's states and territories, the socio-economic distribution of developmental vulnerability across jurisdictions, and how these distributions might have changed over time.
Methods: This study employed multivariable logistic regressions to estimate the probability of developmental vulnerability within each jurisdiction and AEDC collection year (2009 to 2018), adjusting for jurisdictional differences in socio-demographic characteristics. To explore socio-economic inequalities in child development, adjusted slope index of inequality (SII) models were utilised. Findings: The results of this study found reductions in the adjusted prevalence of developmental vulnerability over time in Western Australia (26% to 20%) and Queensland (30% to 25%), with an increase observed in the Australian Capital Territory (27% to 30%). Analysis also indicated an increase in socio-economic inequalities over time in the Northern Territory (+12%), the Australian Capital Territory (+6%) and Tasmania (+4%). Sensitivity analysis found these effects to be robust with an alternative measure of socio-economic position. Interpretation: There is considerable variation in the prevalence and socio-economic inequalities in developmental vulnerability across Australia's jurisdictions. Future research should explore the policy drivers in early childhood education and health contributing to the findings of this study, with a particular focus on jurisdictions where there have been notable changes in developmental vulnerability and socio-economic inequality over time.
Funding: Analyses were funded under research contract by the Department of Education, Skills and Employment. Prof Brinkman is supported by a National Health and Medical Research Council fellowship, APP1160185.Luke R. Collier, Tess Gregory, Yasmin Harman-Smith, Angela Gialamas, Sally A. Brinkma
Quantum magneto-oscillations in a two-dimensional Fermi liquid
Quantum magneto-oscillations provide a powerfull tool for quantifying
Fermi-liquid parameters of metals. In particular, the quasiparticle effective
mass and spin susceptibility are extracted from the experiment using the
Lifshitz-Kosevich formula, derived under the assumption that the properties of
the system in a non-zero magnetic field are determined uniquely by the
zero-field Fermi-liquid state. This assumption is valid in 3D but, generally
speaking, erroneous in 2D where the Lifshitz-Kosevich formula may be applied
only if the oscillations are strongly damped by thermal smearing and disorder.
In this work, the effects of interactions and disorder on the amplitude of
magneto-oscillations in 2D are studied. It is found that the effective mass
diverges logarithmically with decreasing temperature signaling a deviation from
the Fermi-liquid behavior. It is also shown that the quasiparticle lifetime due
to inelastic interactions does not enter the oscillation amplitude, although
these interactions do renormalize the effective mass. This result provides a
generalization of the Fowler-Prange theorem formulated originally for the
electron-phonon interaction.Comment: 4 pages, 1 figur
The holographic superconductors in higher-dimensional AdS soliton
We explore the behaviors of the holographic superconductors at zero
temperature for a charged scalar field coupled to a Maxwell field in
higher-dimensional AdS soliton spacetime via analytical way. In the probe
limit, we obtain the critical chemical potentials increase linearly as a total
dimension grows up. We find that the critical exponent for condensation
operator is obtained as 1/2 independently of , and the charge density is
linearly related to the chemical potential near the critical point.
Furthermore, we consider a slightly generalized setup the
Einstein-Power-Maxwell field theory, and find that the critical exponent for
condensation operator is given as in terms of a power parameter
of the Power-Maxwell field, and the charge density is proportional to the
chemical potential to the power of .Comment: LaTeX, 16 pages, 5 figures, typos corrected, one reference added,
version to appear in European Physical Journal
Introduction to Holographic Superconductors
These lectures give an introduction to the theory of holographic
superconductors. These are superconductors that have a dual gravitational
description using gauge/gravity duality. After introducing a suitable
gravitational theory, we discuss its properties in various regimes: the probe
limit, the effects of backreaction, the zero temperature limit, and the
addition of magnetic fields. Using the gauge/gravity dictionary, these
properties reproduce many of the standard features of superconductors. Some
familiarity with gauge/gravity duality is assumed. A list of open problems is
included at the end.Comment: 34 pages, 10 figures, to appear in the proceedings of the 5th Aegean
Summer School, "From Gravity to Thermal Gauge Theories: the AdS/CFT
Correspondence"; v2: references adde
Precision Measurement of PArity Violation in Polarized Cold Neutron Capture on the Proton: the NPDGamma Experiment
The NPDGamma experiment at the Los Alamos Neutron Science Center (LANSCE) is
dedicated to measure with high precision the parity violating asymmetry in the
emission after capture of spin polarized cold neutrons in
para-hydrogen. The measurement will determine unambiguously the weak
pion-nucleon-nucleon () coupling constant {\it f}Comment: Proceedings of the PANIC'05 Conference, Santa Fe, NM, USA, October
24-28, 2005, 3 pages, 2 figure
Cosmological Creation of D-branes and anti-D-branes
We argue that the early universe may be described by an initial state of
space-filling branes and anti-branes. At high temperature this system is
stable. At low temperature tachyons appear and lead to a phase transition,
dynamics, and the creation of D-branes. These branes are cosmologically
produced in a generic fashion by the Kibble mechanism. From an entropic point
of view, the formation of lower dimensional branes is preferred and
brane-worlds are exponentially more likely to form than higher dimensional
branes. Virtually any brane configuration can be created from such phase
transitions by adjusting the tachyon profile. A lower bound on the number
defects produced is: one D-brane per Hubble volume.Comment: 30 pages, 5 eps figures; v2 more references added; v3 section 4
slightly improve
Black Holes in Higher-Dimensional Gravity
These lectures review some of the recent progress in uncovering the phase
structure of black hole solutions in higher-dimensional vacuum Einstein
gravity. The two classes on which we focus are Kaluza-Klein black holes, i.e.
static solutions with an event horizon in asymptotically flat spaces with
compact directions, and stationary solutions with an event horizon in
asymptotically flat space. Highlights include the recently constructed
multi-black hole configurations on the cylinder and thin rotating black rings
in dimensions higher than five. The phase diagram that is emerging for each of
the two classes will be discussed, including an intriguing connection that
relates the phase structure of Kaluza-Klein black holes with that of
asymptotically flat rotating black holes.Comment: latex, 49 pages, 5 figures. Lectures to appear in the proceedings of
the Fourth Aegean Summer School, Mytiline, Lesvos, Greece, September 17-22,
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