118 research outputs found
Domain-wall/Cosmology correspondence in adS/dS supergravity
We realize the domain-wall/cosmology correspondence for
(pseudo)supersymmetric domain walls (cosmologies) in the context of
four-dimensional supergravity. The OSp(2|4)-invariant anti-de Sitter (adS)
vacuum of a particular N=2 Maxwell-Einstein supergravity theory is shown to
correspond to the OSp(2^*|2,2)-invariant de Sitter (dS) vacuum of a particular
pseudo-supergravity model, with `twisted' reality conditions on spinors. More
generally, supersymmetric domain walls of the former model correspond to
pseudo-supersymmetric cosmologies of the latter model, with time-dependent
pseudo-Killing spinors that we give explicitly.Comment: 21 pages;v2: rewritten to clarify the link with fake supergravity --
main results unchanged; v3: typos corrected, two refs added, JHEP versio
Axion-Dilaton Cosmology and Dark Energy
We discuss a class of flat FRW cosmological models based on D=4 axion-dilaton
gravity universally coupled to cosmological background fluids. In particular,
we investigate the possibility of recurrent acceleration, which was recently
shown to be generically realized in a wide class of axion-dilaton models, but
in absence of cosmological background fluids. We observe that, once we impose
the existence of radiation -and matter- dominated earlier stages of cosmic
evolution, the axion-dilaton dynamics is altered significantly with respect to
the case of pure axion-dilaton gravity. During the matter dominated epoch the
scalar fields remain either frozen, due to the large expansion rate, or enter a
cosmological scaling regime. In both cases, oscillations of the effective
equation of state around the acceleration boundary value are impossible. Models
which enter an oscillatory stage in the low redshift regime, on the other hand,
are disfavored by observations. We also comment on the viability of the
axion-dilaton system as a candidate for dynamical dark energy. In a certain
subclass of models, an intermediate scaling regime is succeeded by eternal
acceleration. We also briefly discuss the issue of dependence on initial
conditions.Comment: 28 pages, 11 figure
Pseudo-supersymmetry and a Tale of Alternate Realities
We discuss how all variant 10d and 11d maximal supergravities, including star
supergravities and supergravities in different signatures, can be obtained as
different real slices of three complex actions. As an application we study the
recently introduced domain-wall/cosmology correspondence in this approach. We
give an example in 9d and 10d where the domain-wall and corresponding cosmology
can be viewed as different real slices of the same complex solution. We argue
how in this case the pseudo-supersymmetry of the cosmological solutions can be
understood as the invariance under supersymmetry of a variant supergravity.Comment: 32 page
Landau Levels, Magnetic Fields and Holographic Fermi Liquids
We further consider a probe fermion in a dyonic black hole background in
anti-de Sitter spacetime, at zero temperature, comparing and contrasting two
distinct classes of solution that have previously appeared in the literature.
Each class has members labeled by an integer n, corresponding to the n-th
Landau level for the fermion. Our interest is the study of the spectral
function of the fermion, interpreting poles in it as indicative of
quasiparticles associated with the edge of a Fermi surface in the
holographically dual strongly coupled theory in a background magnetic field H
at finite chemical potential. Using both analytical and numerical methods, we
explicitly show how one class of solutions naturally leads to an infinite
family of quasiparticle peaks, signaling the presence of a Fermi surface for
each level n. We present some of the properties of these peaks, which fall into
a well behaved pattern at large n, extracting the scaling of Fermi energy with
n and H, as well as the dispersion of the quasiparticles.Comment: 23 pages, 4 figures. Changed some of the terminology: non-separable
-> infinite-sum. Clarified the relationship between our ansatz and the
separable ansat
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
Small Hairy Black Holes in Global AdS Spacetime
We study small charged black holes in global AdS spacetime in the presence of
a charged massless minimally coupled scalar field. In a certain parameter range
these black holes suffer from well known superradiant instabilities. We
demonstrate that the end point of the resultant tachyon condensation process is
a hairy black hole which we construct analytically in a perturbative expansion
in the black hole radius. At leading order our solution is a small undeformed
RNAdS black hole immersed into a charged scalar condensate that fills the AdS
`box'. These hairy black hole solutions appear in a two parameter family
labelled by their mass and charge. Their mass is bounded from below by a
function of their charge; at the lower bound a hairy black hole reduces to a
regular horizon free soliton which can also be thought of as a nonlinear Bose
condensate. We compute the microcanonical phase diagram of our system at small
mass, and demonstrate that it exhibits a second order `phase transition'
between the RNAdS black hole and the hairy black hole phases.Comment: 68+1 pages, 18 figures, JHEP format. v2 : small typos corrected and a
reference adde
Holographic Superconductors with Power-Maxwell field
With the Sturm-Liouville analytical and numerical methods, we investigate the
behaviors of the holographic superconductors by introducing a complex charged
scalar field coupled with a Power-Maxwell field in the background of
-dimensional Schwarzschild AdS black hole. We note that the Power-Maxwell
field takes the special asymptotical solution near boundary which is different
from all known cases. We find that the larger power parameter for the
Power-Maxwell field makes it harder for the scalar hair to be condensated. We
also find that, for different , the critical exponent of the system is still
1/2, which seems to be an universal property for various nonlinear
electrodynamics if the scalar field takes the form of this paper.Comment: 14 pages, 1 figure, and 2 table
Analytical study on holographic superconductors in external magnetic field
We investigate the holographic superconductors immersed in an external
magnetic field by using the analytical approach. We obtain the spatially
dependent condensate solutions in the presence of the magnetism and find
analytically that the upper critical magnetic field satisfies the relation
given in the Ginzburg-Landau theory. We observe analytically the reminiscent of
the Meissner effect where the magnetic field expels the condensate. Extending
to the D-dimensional Gauss-Bonnet AdS black holes, we examine the influence
given by the Gauss-Bonnet coupling on the condensation. Different from the
positive coupling, we find that the negative Gauss-Bonnet coupling enhances the
condensation when the external magnetism is not strong enough.Comment: revised version, to appear in JHE
Maxwell-Chern-Simons Vortices and Holographic Superconductors
We investigate probe limit vortex solutions of a charged scalar field in
Einstein-Maxwell theory in 3+1 dimensions, for an asymptotically AdS
Schwarzschild black hole metric with the addition of an axionic coupling to the
Maxwell field. We show that the inclusion of such a term, together with a
suitable potential for the axion field, can induce an effective Chern-Simons
term on the 2+1 dimensional boundary. We obtain numerical solutions of the
equations of motion and find Maxwell-Chern-Simons like magnetic vortex
configurations, where the magnetic field profile varies with the size of the
effective Chern-Simons coupling. The axion field has a non-trivial profile
inside the AdS bulk but does not condense at spatial infinity.Comment: 17 pages, 5 figures, version accepted for publication in JHE
The incremental yield of prenatal exome sequencing over chromosome microarray for congenital heart abnormalities:A systematic review and meta-analysis
ObjectivesTo determine the incremental yield of prenatal exome sequencing (PES) over standard testing in fetuses with an isolated congenital heart abnormality (CHA), CHA associated with extra-cardiac malformations (ECMs) and CHA dependent upon anatomical subclassification.MethodsA systematic review of the literature was performed using MEDLINE, EMBASE, Web of Science and grey literature January 2010-February 2023. Studies were selected if they included greater than 20 cases of prenatally diagnosed CHA when standard testing (QF-PCR/chromosome microarray/karyotype) was negative. Pooled incremental yield was determined. PROSPERO CRD 42022364747.ResultsOverall, 21 studies, incorporating 1957 cases were included. The incremental yield of PES (causative pathogenic and likely pathogenic variants) over standard testing was 17.4% (95% CI, 13.5%-21.6%), 9.3% (95% CI, 6.6%-12.3%) and 35.9% (95% CI, 21.0%-52.3%) for all CHAs, isolated CHAs and CHAs associated with ECMs. The subgroup with the greatest yield was complex lesions/heterotaxy; 35.2% (95% CI 9.7%-65.3%). The most common syndrome was Kabuki syndrome (31/256, 12.1%) and most pathogenic variants occurred de novo and in autosomal dominant (monoallelic) disease causing genes (114/224, 50.9%).ConclusionThe likelihood of a monogenic aetiology in fetuses with multi-system CHAs is high. Clinicians must consider the clinical utility of offering PES in selected isolated cardiac lesions.What is already known?Congenital heart abnormalities are the most commonly occurring congenital anomalies and can be associated with chromosomal or monogenic conditions. With the increasing use of fetal sequencing, there is a need to define the association between monogenic conditions and specific cardiac abnormalities, particularly when isolated to facilitate triaging for prenatal sequencing.What does this study add?The incremental yield of prenatal exome sequencing over and above chromosome microarray for congenital heart abnormalities is 9.3% in isolated lesions and 35.2% in the presence of complex lesions/heterotaxy. Clinicians should consider the clinical utility of offering prenatal exome sequencing in selected isolated cardiac lesions dependent on resources available
- …