scholarly journals Cosmological perturbations of a quartet of scalar fields with a spatially constant gradient

2013 ◽  
Vol 88 (4) ◽  
Author(s):  
Seoktae Koh ◽  
Seyen Kouwn ◽  
O-Kab Kwon ◽  
Phillial Oh
Keyword(s):  
Scalar Fields ◽  
Cosmological Perturbations ◽  
Constant Gradient

scholarly journals Cosmological perturbations with multiple scalar fields

2000 ◽  
Vol 495 (3-4) ◽  
pp. 277-283 ◽  
Author(s):  
Jai-chan Hwang ◽  
Hyerim Noh
Keyword(s):  
Scalar Fields ◽  
Cosmological Perturbations

scholarly journals A settling-driven instability in two-component, stably stratified fluids

2017 ◽  
Vol 816 ◽  
pp. 243-267 ◽  
Author(s):  
A. Alsinan ◽  
E. Meiburg ◽  
P. Garaud
Keyword(s):  
Linear Stability ◽  
Settling Velocity ◽  
Scalar Fields ◽  
State Density ◽  
Stratified Fluids ◽  
Instability Mechanism ◽  
Two Component ◽  
Constant Gradient ◽  
Stability Results ◽  
Double Diffusive

We analyse the linear stability of stably stratified fluids whose density depends on two scalar fields where one of the scalar fields is unstably stratified and involves a settling velocity. Such conditions may be found, for example, in flows involving the transport of sediment in addition to heat or salt. A linear stability analysis for constant-gradient base states demonstrates that the settling velocity generates a phase shift between the perturbation fields of the two scalars, which gives rise to a novel, settling-driven instability mode. This instability mechanism favours the growth of waves that are inclined with respect to the horizontal. It is active for all density and diffusivity ratios, including for cases in which the two scalars diffuse at identical rates. If the scalars have unequal diffusivities, it competes with the elevator mode waves of the classical double-diffusive instability. We present detailed linear stability results as a function of the governing dimensionless parameters, including for lateral gradients of the base state density fields that result in predominantly horizontal intrusion instabilities. Highly resolved direct numerical simulation results serve to illustrate the nonlinear competition of the various instabilities for such flows in different parameter regimes.

scholarly journals New AdS4 vacua in dyonic ISO(7) gauged supergravity

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Nikolay Bobev ◽  
Thomas Fischbacher ◽  
Fridrik Freyr Gautason ◽  
Krzysztof Pilch
Keyword(s):  
Scalar Fields ◽  
Global Symmetry ◽  
Supergravity Theory

Abstract We identify 219 AdS4 solutions in four-dimensional dyonically gauged ISO(7) $$ \mathcal{N} $$ N = 8 supergravity and present some of their properties. One of the new solutions preserves $$ \mathcal{N} $$ N = 1 supersymmetry and provides a rare explicit example of an AdS4 vacuum dual to a 3d SCFT with no continuous global symmetry. There are also two new non-supersymmetric solutions for which all 70 scalar fields in the supergravity theory have masses above the BF bound. All of these AdS4 solutions can be uplifted to massive type IIA supergravity. Motivated by this we present the low lying operator spectra of the dual 3d CFTs for all known supersymmetric AdS4 solutions in the theory and organize them into superconformal multiplets.

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