Desingularization of the Milne Universe

Resolution of cosmological singularities is an important problem in any full theory of quantum gravity. The Milne orbifold is a cosmology with a big-bang/big-crunch singularity, but being a quotient of flat space it holds potential for resolution in string theory. It is known however, that some perturbative string amplitudes diverge in the Milne geometry. Here we show that flat space higher spin theories can effect a simple resolution of the Milne singularity when one embeds the latter in 2+1 dimensions. We explain how to reconcile this with the expectation that non-perturbative string effects are required for resolving Milne. Along the way, we introduce a Grassmann realization of the \.{I}n\"on\"u-Wigner contraction to export much of the AdS technology to our flat space computation.Comment: 4 pages, revtex, v2: minor clarifications/corrections, refs added, v3: minor error corrected, v4: published PLB version (essentially

Higher Spin Resolution of a Toy Big Bang

Diffeomorphisms preserve spacetime singularities, whereas higher spin symmetries need not. Since three dimensional de Sitter space has quotients that have big-bang/big-crunch singularities and since dS_3-gravity can be written as an SL(2,C) Chern-Simons theory, we investigate SL(3,C) Chern-Simons theory as a higher-spin context in which these singularities might get resolved. As in the case of higher spin black holes in AdS_3, the solutions are invariantly characterized by their holonomies. We show that the dS_3 quotient singularity can be de-singularized by an SL(3,C) gauge transformation that preserves the holonomy: this is a higher spin resolution the cosmological singularity. Our work deals exclusively with the bulk theory, and is independent of the subtleties involved in defining a CFT_2 dual to dS_3 in the sense of dS/CFT.Comment: v2-v3: typos removed, refs added. v4: minor improvements, Phys Rev D version, v5: one more typo fixed, footnote adde

Holographic bulk reconstruction beyond (super)gravity

We outline a holographic recipe to reconstruct $\alpha'$ corrections to AdS (quantum) gravity from an underlying CFT in the strictly planar limit ($N\rightarrow\infty$). Assuming that the boundary CFT can be solved in principle to all orders of the 't Hooft coupling $\lambda$, for scalar primary operators, the $\lambda^{-1}$ expansion of the conformal dimensions can be mapped to higher curvature corrections of the dual bulk scalar field action. Furthermore, for the metric pertubations in the bulk, the AdS/CFT operator-field isomorphism forces these corrections to be of the Lovelock type. We demonstrate this by reconstructing the coefficient of the leading Lovelock correction, aka the Gauss-Bonnet term in a bulk AdS gravity action using the expression of stress-tensor two-point function up to sub-leading order in $\lambda^{-1}$.Comment: 19 pages, typos corrected, published version (journal version title is different

A Grassmann Path From AdS_3 to Flat Space

We show that interpreting the inverse AdS_3 radius 1/l as a Grassmann variable results in a formal map from gravity in AdS_3 to gravity in flat space. The underlying reason for this is the fact that ISO(2,1) is the Inonu-Wigner contraction of SO(2,2). We show how this works for the Chern-Simons actions, demonstrate how the general (Banados) solution in AdS_3 maps to the general flat space solution, and how the Killing vectors, charges and the Virasoro algebra in the Brown-Henneaux case map to the corresponding quantities in the BMS_3 case. Our results straightforwardly generalize to the higher spin case: the recently constructed flat space higher spin theories emerge automatically in this approach from their AdS counterparts. We conclude with a discussion of singularity resolution in the BMS gauge as an application.Comment: 20 pages, 1 figure; v2: many refs added, minor changes, v3: typos fixed, one more ref added, JHEP versio

Fluids, Anomalies and the Chiral Magnetic Effect: A Group-theoretic Formulation

It is possible to formulate fluid dynamics in terms of group-valued variables. This is particularly suited to the cases where the fluid has nonabelian charges and is coupled to nonabelian gauge fields. We explore this formulation further in this paper. An action for a fluid of relativistic particles (with and without spin) is given in terms of the Lorentz and Poincare (or de Sitter) groups. Considering the case of particles with flavor symmetries, a general fluid action which also incorporates all flavor anomalies is given. The chiral magnetic and chiral vorticity effects as well as the consequences of the mixed gauge-gravity anomaly are discussed.Comment: 17 pages, version to be published in Phys Rev

Higher Spin Cosmology

We construct cosmological solutions of higher spin gravity in 2+1 dimensional de Sitter space. We show that a consistent thermodynamics can be obtained for their horizons by demanding appropriate holonomy conditions. This is equivalent to demanding the integrability of the Euclidean boundary CFT partition function, and reduces to Gibbons-Hawking thermodynamics in the spin-2 case. By using a prescription of Maldacena, we relate the thermodynamics of these solutions to those of higher spin black holes in AdS_3.Comment: 21 pages, v2: many typos fixed, refs added, v3: minor corrections/improvements, Phys. Rev. D version, v4: one more re

Black Hole Formation at the Correspondence Point

We study the process of bound state formation in a D-brane collision. We consider two mechanisms for bound state formation. The first, operative at weak coupling in the worldvolume gauge theory, is pair creation of W-bosons. The second, operative at strong coupling, corresponds to formation of a large black hole in the dual supergravity. These two processes agree qualitatively at intermediate coupling, in accord with the correspondence principle of Horowitz and Polchinski. We show that the size of the bound state and timescale for formation of a bound state agree at the correspondence point. The timescale involves matching a parametric resonance in the gauge theory to a quasinormal mode in supergravity.Comment: 29 pages, 5 figures. v2: minor improvements, additional reference, version to appear in PR

An Economic policy and legal analysis of the Micro Finance Institutions (Development & Regulation) Bill, 2011

In response to the Second Micro Finance Crisis in Andhra Pradesh, which took place in October 2010, the Ministry of Finance has pro- posed a new Micro Finance Institutions (Development & Regulation) Bill. This paper undertakes a detailed analysis of the draft Bill in terms of both economic policy and law. This analysis reveals many weak links, including: a lack of clarity on the objectives of the Bill; an insufficient focus on protection of the rights of the micro-borrower; lack of clarity about the definition of thrift; the loss of accountability that comes with multiple regulatory agencies; concerns about the rule of law; and constitutional issues about powers of the Centre versus the State Government.microfinance, regulation, crisis resolution, consumer credit, consumer protection, regulatory objectives

Black Hole Formation in Fuzzy Sphere Collapse

We study the collapse of a fuzzy sphere, that is a spherical membrane built out of D0-branes, in the BFSS model. At weak coupling, as the sphere shrinks, open strings are produced. If the initial radius is large then open string production is not important and the sphere behaves classically. At intermediate initial radius the back-reaction from open string production is important but the fuzzy sphere retains its identity. At small initial radius the sphere collapses to form a black hole. The crossover between the later two regimes is smooth and occurs at the correspondence point of Horowitz and Polchinski.Comment: 27 pages, LaTeX, 2 figures. v2: additional reference