Global AdS Research Articles

Bubbles unbound II: AdS and the single bubble

I present further analytic time symmetric initial data for five dimensions describing ``bubbles of nothing'' which have no Kaluza-Klein circle asymptotically. The new solutions consist of a large family of single bubbles in both asymptotically flat and asymptotically AdS space. I also numerically construct gravitational solitons in AdS where the usual boundary conditions are modified geometrically but not topologically. Furthermore I point out there are both regular AdS bubbles and topologically trivial metrics in asymptotically global AdS dual to matter which violates all the usual energy conditions, both classical and quantum. I inquire as to the existence of a dual gravitational instability.

Expanding plasmas and quasinormal modes of anti-de Sitter black holes

We compute the gravitational quasinormal modes of the global AdS_5-Schwarzschild solution. We show how to use the holographic dual of these modes to describe a thermal plasma of finite extent expanding in a slightly anisotropic fashion. We compare these flows with the behavior of quark-gluon plasmas produced in relativistic heavy ion collisions by estimating the elliptic flow coefficient and the thermalization time.

Higher derivative corrections to near-extremal black holes in type IIB supergravity

We discuss string theory α ′ corrections to charged near-extremal black 3-branes/black holes in type IIB supergravity. We find that supersymmetric global AdS 5 × S 5 geometry is not corrected to leading order in α ′ , while charged or non-extremal black 3-branes/black hole geometries receive α ′ corrections. Following gauge theory-string theory correspondence the thermodynamics of these geometries is mapped to the thermodynamics of large- n c N = 4 supersymmetric Yang–Mills theory at finite (large) 't Hooft coupling with the U ( 1 ) R -charge chemical potential. We use holographic renormalization to compute the Gibbs free energy and the ADM mass of the near-extremal solutions. The remaining thermodynamic potentials are evaluated enforcing the first law of thermodynamics. We present analytic expressions for the α ′ corrected thermodynamics of black holes in AdS 5 × S 5 and the thermodynamics of charged black 3-branes with identical chemical potentials for [ U ( 1 ) R ] 3 charges and large (compare to chemical potential) temperature. We compute α ′ corrections to Hawking–Page phase transition. We find that for nonzero chemical potential thermodynamics of near-extremal black 3-brane solution receives ln T correction to leading order in α ′ .

Going Global: An Analysis of Global Women's Magazine ADS in China

Over the past few decades, some women's magazines have rapidly spread as a global medium. While previous researchers have noted that women's magazines act as agents of socialisation, perpetuating certain gender stereotypes and institutionalising certain gender conventions, there has been little research on how this global medium portrays women of various races. Combining content and semiotic analyses, this article is an examination of the context and content of ads that have appeared in the Chinese versions of global women's magazines. The study focused on Elle, Cosmopolitan, Marie Claire and Harper's Bazaar, all global titles currently marketed in the Chinese mainland. Findings suggest that women of different races tend to be stereotyped in different ways in these magazines, and that Western models are presented in significantly different ways from Asian models. The impact of globalisation on these differences and the implications of the findings for global advertising are discussed.

Negative mass solitons in gravity

We first reconstruct the conserved (Abbott-Deser) charges in the spin-connection formalism of gravity for asymptotically (Anti)-de Sitter spaces, and then compute the masses of the $AdS$ soliton and the recently found Eguchi-Hanson solitons in generic odd dimensions, unlike the previous result obtained for only five dimensions. These solutions have negative masses compared to the global $AdS$ or $AdS/{Z}_{p}$ spacetimes. As a separate note, we also compute the masses of the recent even dimensional Taub-NUT-Reissner-Nordstr\"om metrics.

A Multi-Boundary AdS Orbifold and DLCQ Holography: A universal holographic description of extremal black hole horizons

We examine a stationary but non-static asymptotically AdS_3 spacetime with two causally connected conformal boundaries, each of which is a ``null cylinder'', namely a cylinder with a null direction identified. This spacetime arises from three different perspectives: (i) as a non-singular, causally regular orbifold of global AdS_3 by boosts, (ii) as a Penrose-like limit focusing on the horizon of extremal BTZ black holes, and (iii) as an S^1 fibration over AdS_2. Each of these perspectives sheds an interesting light on holography. Examination of the conformal boundary of the spacetime shows that the dual to the space should involve DLCQ limits of the D1-D5 conformal field theory. The Penrose-like limit approach leads to a similar conclusion, by isolating a sector of the complete D1-D5 CFT that describes the physics in the vicinity of the horizon of an extremal black hole. As such this is a holographic description of the universal horizon dynamics of the extremal black holes in AdS_3 and also of the four and five dimensional stringy black holes whose states were counted in string theory. The AdS_2 perspective draws a connection to a 0+1d quantum mechanical theory. Various dualities lead to a Matrix model description of the spacetime. Many interesting issues that are related to both de Sitter physics and attempts to ``see behind a horizon'' using AdS/CFT arise from (a) the presence of two disconnected components to the boundary, and (b) the analytic structure of bulk physics in the complex coordinate plane.

Gravitational Lorentz Violations from M-Theory

In an attempt to bridge the gap between M-theory and braneworld phenomenology, we present various gravitational Lorentz-violating braneworlds which arise from p-brane systems. Lorentz invariance is still preserved locally on the braneworld. For certain p-brane intersections, the massless graviton is quasi-localized. This also results from an M5-brane in a C-field. In the case of a p-brane perturbed from extremality, the quasi-localized graviton is massive. For a braneworld arising from global AdS_5, gravitons travel faster when further in the bulk, thereby apparently traversing distances faster than light.

Null orbifolds in AdS, Time Dependence and Holography

We study M/D-branes in a null-brane background. By taking a near horizon limit, one is left with cosmological models in the corresponding Poincar\'e patches. To deal with their usual horizons, we either extend these models to global AdS or remain in the Poincar\'e patch and apply a T-duality transformation whenever the effective radius of the compact dimension associated with the null-brane probes distances smaller than the string scale. The first scenario gives rise to null orbifolds in AdS spaces, which are described in detail. Their conformal boundaries are singular. The second has a dual gauge theory description in terms of Super Yang-Mills in the null-brane background. The latter is a good candidate for a non-perturbative definition of string theory in a time-dependent background.

Anti-de-Sitter black hole thermodynamics in higher derivative gravity and new confining–deconfining phases in dual CFT

The thermodynamics of d5 AdS BHs with positive, negative or zero curvature spatial section in higher derivative (HD) gravity is described. HD contribution to free energy may change its sign which leads to more complicated regime for Hawking-Page phase transitions. Some variant of d5 HD gravity is dual to ${\cal N}=2$ $Sp(N)$ SCFT up to the next-to-leading order in large $N$. Then, according to Witten interpretation the stable AdS BH phase corresponds to deconfinement while global AdS phase corresponds to confinement. Unlike to Einstein gravity in HD theory the critical $N$ appears. It may influence the phase transition structure. In particulary, what was confining phase above the critical value becomes the deconfining phase below it and vice-versa.

Scalar field spacetimes and the anti–de Sitter space/conformal-field theory conjecture

We describe a class of asymptotically AdS scalar field spacetimes, and calculate the associated conserved charges for three, four and five spacetime dimensions using the conformal and counterterm prescriptions. The energy associated with the solutions in each case is proportional to $\sqrt{{M}^{2}\ensuremath{-}{k}^{2}},$ where M is a constant and k is a scalar charge. In five spacetime dimensions, the counterterm prescription gives an additional vacuum (Casimir) energy, which agrees with that found in the context of AdS conformal-field theory (CFT) correspondence. We find a surprising degeneracy: the energy of the ``extremal'' scalar field solution $M=k$ equals the energy of global AdS. This result is discussed in light of the AdS/CFT conjecture.

A Stress Tensor for Anti-de Sitter Gravity

We propose a procedure for computing the boundary stress tensor associated with a gravitating system in asymptotically anti-de Sitter space. Our definition is free of ambiguities encountered by previous attempts, and correctly reproduces the masses and angular momenta of various spacetimes. Via the AdS/CFT correspondence, our classical result is interpretable as the expectation value of the stress tensor in a quantum conformal field theory. We demonstrate that the conformal anomalies in two and four dimensions are recovered. The two dimensional stress tensor transforms with a Schwarzian derivative and the expected central charge. We also find a nonzero ground state energy for global AdS_5, and show that it exactly matches the Casimir energy of the dual N=4 super Yang-Mills theory on S^3 x R.