We introduce a new kind of space-filling brane, which we term "G-brane" because its action is a descendant of the gravitational action. The G-brane may be thought of as the remanent of the gravitational field when the propagating gravitons are removed. The G-brane is different from the Dirac or Nambu space-filling branes. Its properties in any spacetime dimension D are exhibited. When the spacetime dimension D is greater than or equal to three, the G-brane does not possess propagating degrees of freedom, just as the Dirac or Nambu branes. For D=3 the G-brane yields a reformulation of gravitation theory in which the Hamiltonian constraints can be solved explicitly, while keeping the spacetime structure manifest. For D=2 the G-brane provides a realization of the conformal algebra, i.e. a conformal field theory, in terms of two scalar fields and their conjugates, which possesses a classical central charge. In the G-brane reformulation of (2+1) gravity, the boundary degrees of freedom of the gravitational field in asymptotically anti-de Sitter space appear as "matter" coupled to the (1+1) G-brane on the boundary.
We present a classical conformal field theory on an arbitrary two-dimensional spacetime background. The dynamical object is a space-filling string, and the evolution may be thought as occurring on the manifold of the conformal group. The theory is a "descendant" of the theory of gravitation in two-dimensional spacetime. The discussion is based on the relation of the deformations of the space-filling string with conformal transformations. The realization of the conformal algebra in terms of surface deformations possesses a classical central charge. The action principle, the conformal and Weyl i…
We consider in any dimension the supersymmetric $\mathbb{Z}_2$ truncations of the maximal supergravity theories. In each dimension and for each truncation we determine all the sets of 1/2-BPS space-filling branes that preserve the supersymmetry of the truncated theory and the representations of the symmetry of such theory to which they belong. We show that in any dimension below eight these sets always contain exotic branes, that are objects that do not have a ten-dimensional origin. We repeat the same analysis for half-maximal theories and for the quarter-maximal theories in four and three di…
We study world-volume effective theories of five-branes in type II string theories. We determine the bosonic zero-modes of the NS5-brane, the Kaluza-Klein monopole, the exotic Q5-, R5-branes and a space-filling brane, by direct calculations within the formalism of double field theory (DFT). We show that these zero-modes are Nambu-Goldstone modes associated with the spontaneously broken gauge symmetries in DFT. They are organized into the bosonic part of the six-dimensional $\mathcal{N} = (1,1)$ vector and the $\mathcal{N} = (2,0)$ tensor multiplets. Among other things, we examine the locally n…
We use holography to study sound modes of strongly-interacting conformal field theories with non-zero temperature, $T$, and $U(1)$ chemical potential, $μ$. Specifically, we consider charged black brane solutions of Einstein gravity in $(3+1)$-dimensional Anti-de Sitter space coupled to a $U(1)$ gauge field with Dirac-Born-Infeld action, representing a spacetime-filling brane. The brane action has two free parameters: the tension and the non-linearity parameter, which controls higher-order terms in the field strength. For all values of the tension, non-linearity parameter, and $T/μ$, and at suf…
We study the shear momentum diffusion and related modes of a strongly coupled $(2+1)$-dimensional conformal field theory at finite temperature and chemical potential, using a dual holographic description. We consider a space-time filling charged black brane solution of Einstein's gravity in $(3+1)$-dimensional asymptotically Anti-de Sitter space coupled to a $U(1)$ gauge field via a Dirac-Born-Infeld action. In addition to temperature and chemical potential, the holographic model has two other parameters: the tension of the brane, and the non-linearity parameter controlling the higher-derivati…
Isometric Embeddings and Noncommutative Branes in Homogeneous Gravitational Waves
我们刻画了由一个常数Neveu-Schwarz三形式通量支持的六维Cahen-Wallach pp波中对称D膜上的世界体积理论。我们发现一类平坦的非对易欧氏D3-膜类似于膜在一个恒定的磁场，以及弯曲的非对易洛伦兹D3-膜类似于膜在一个电的背景。在前一种情况下，膜上的非对易场论是从第一性原理构造的，与世界体积中模糊球的动力学有关，并用于分析弦论的平坦空间极限。背景中所有其他对称膜上的世界体积理论都是局域场论。所有这些理论的物理起源都是通过时空中膜的等距嵌入和具有Neveu-Schwarz三形式通量的AdS 3 x S3的Penrose-Gueven极限之间的相互作用来描述的。非对称时空填充D-膜的非对易场论也被构造，给出了类似于Dolan-Nappi模型的空间变化但与时间无关的非对易性。
We study the effective potentials for various probe branes surrounding AdS$_4$ black holes with massive halos in consistent truncations of M-theory on the Sasaki-Einstein$_7$ manifolds $Q^{111}$ and $M^{111}$. These probes are either M2 branes extended in spacetime or "particle-like" probes such as internally wrapped M2 branes and, upon reduction to type IIA string theory, D6 branes corresponding to baryon operators in the dual Chern-Simons theory. We find both global and local minima of the potential outside the horizon, indicating the existence of stable and metastable multicenter AdS black …
We obtain a four-dimensional supergravity with spontaneously broken supersymmetry allowing for de Sitter vacua by coupling a superspace action of minimal N=1, D=4 supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action describing the dynamics of a space-filling non-BPS 3-brane in N=1, D=4 superspace. To the quadratic order in the goldstino field the obtained action coincides with earlier constructions of supergravities with nilpotent superfields, while matching the higher-order contributions will require a non-linear redefinition of fields. In the unitary …
In this work we study type IIB Calabi-Yau orientifold compactifications in the presence of space-time filling D7-branes and O7-planes. In particular, we conclude that $α'^2 g_s$-corrections to their DBI actions lead to a modification of the four-dimensional $\mathcal{N}=1$ Kähler potential and coordinates. We focus on the one-modulus case of the geometric background i.e. $h^{1,1}=1$ where we find that the $α'^2 g_s$-correction is of topological nature. It depends on the first Chern form of the four-cycle of the Calabi-Yau orientifold which is wrapped by the D7-branes and O7-plane. This is in a…
The strong-field limit for the 2-form potential on an M5-brane yields a conformal chiral 2-form electrodynamics in six dimensions, with gauge-invariant self-interactions but no adjustable coupling constant; the stress tensor is that of a null fluid. Lorentz invariance can be made manifest via an interpretation as a tensionless `space-filling M5-brane', or as a truncation of the infra-red dynamics of an M5-brane in AdS7 x S4.
