Holographic RG Flows and Universal Structures on the Coulomb Branch of N=2 Supersymmetric Large n Gauge Theory

We report on our results of D3-brane probing a large class of generalised type IIB supergravity solutions presented very recently in the literature. The structure of the solutions is controlled by a single non-linear differential equation. These solutions correspond to renormalisation group flows from pure N=4 supersymmetric gauge theory to an N=2 gauge theory with a massive adjoint scalar. The gauge group is SU(n) with n large. After presenting the general result, we focus on one of the new solutions, solving for the specific coordinates needed to display the explicit metric on the moduli space. We obtain an appropriately holomorphic result for the coupling. We look for the singular locus, and interestingly, the final result again manifests itself in terms of a square root branch cut on the complex plane, as previously found for a set of solutions for which the details are very different. This, together with the existence of the single simple non-linear differential equation, is further evidence in support of an earlier suggestion that there is a very simple model --perhaps a matrix model with relation to the Calogero-Moser integrable system-- underlying this gauge theory physics.Comment: 14 pages, LaTeX, 1 figur

Quark Soup al dente: Applied Superstring Theory

We discuss the application of the AdS/CFT correspondence to possibly gain new physical insights for the strongly coupled quark-gluon plasma. This article provides an informal summary of a talk given by RCM at the 18th International Conference on General Relativity and Gravitation in July 2007.Comment: This article provides an informal summary of a talk given by RCM at the 18th International Conference on General Relativity and Gravitation in July 200

Comments on the T-dual of the gravity dual of D5-branes on S3S^3

We consider an abelian T-duality on a deformation of the gravitational solution of \cite{Maldacena2001}, which is the gravity dual of $N_c$ D5-branes wrapping a three-cycle inside a manifold that admits a $G_2$ structure. Performing the T-duality we find $N_c$ D$4$-branes wrapping a two-cycle with non-trivial antisymmetric fields in the NS-NS and RR sector. We study some aspects of its dual field theory and we compare with the original solution.Comment: 26 page

Gravity Dual of a Quantum Hall Plateau Transition

We show how to model the transition between distinct quantum Hall plateaus in terms of D-branes in string theory. A low energy theory of 2+1 dimensional fermions is obtained by considering the D3-D7 system, and the plateau transition corresponds to moving the branes through one another. We study the transition at strong coupling using gauge/gravity duality and the probe approximation. Strong coupling leads to a novel kind of plateau transition: at low temperatures the transition remains discontinuous due to the effects of dynamical symmetry breaking and mass generation, and at high temperatures is only partially smoothed out.Comment: 27 pages, 6 figures, harvmac; v2, references and minor comments added, version to be submitted to JHEP; v3, corrections to section

T-Duality from super Lie n-algebra cocycles for super p-branes

We compute the $L_\infty$-theoretic dimensional reduction of the F1/D$p$-brane super $L_\infty$-cocycles with coefficients in rationalized twisted K-theory from the 10d type IIA and type IIB super Lie algebras down to 9d. We show that the two resulting coefficient $L_\infty$-algebras are naturally related by an $L_\infty$-isomorphism which we find to act on the super $p$-brane cocycles by the infinitesimal version of the rules of topological T-duality and inducing an isomorphism between $K^0$ and $K^1$, rationally. In particular this is a derivation of the Buscher rules for RR-fields (Hori's formula) from first principles. Moreover, we show that these $L_\infty$-algebras are the homotopy quotients of the RR-charge coefficients by the "T-duality Lie 2-algebra". We find that the induced $L_\infty$-extension is a gerby extension of a 9+(1+1) dimensional (i.e. "doubled") T-duality correspondence super-spacetime, which serves as a local model for T-folds. We observe that this still extends, via the D0-brane cocycle of its type IIA factor, to a 10+(1+1)-dimensional super Lie algebra. Finally we observe that this satisfies expected properties of a local model space for F-theory elliptic fibrations.Comment: 44 pages; v2: added more discussion of double dimensional reduction via cyclic L-infinity cohomology; v3: added derivation of Buscher rules for RR-fields, expanded on role of curved L-infinity algebras in double dimensional reductio

Memories of a Theoretical Physicist

A groundbreaking theoretical physicist traces his career, reflecting on the successes and failures, triumphs and insecurities of a life cut short by cancer. The groundbreaking theoretical physicist Joseph Polchinski explained the genesis of his memoir this way: “Having only two bodies of knowledge, myself and physics, I decided to write an autobiography about my development as a theoretical physicist.” In this posthumously published account of his life and work, Polchinski (1954–2018) describes successes and failures, triumphs and insecurities, and the sheer persistence that led to his greatest discoveries. Writing engagingly and accessibly, with the wry humor for which he was known, Polchinski gives theoretical physics a very human face. Polchinski, famous for his contributions to string theory, may have changed the course of modern theoretical physics, but he was a late bloomer—doing most of his important work after the age of forty. His death from brain cancer at sixty-three cut short a career at its peak. Working on the memoir after his diagnosis, using a text-to-speech algorithm because he could no longer read words on a page, he was able to recapitulate his entire career, down to the details of problems he had worked on. For Polchinski, physics went deeper than words. This edition includes photographs from Polchinski's professional and family life, as well as physics explainer boxes, other technical edits, and bibliographic notes by his former student Ahmed Almheiri, a foreword by Andrew Strominger, and an afterword by his wife Dorothy Chun and sons Steven and Daniel