Spring 2008

Apr. 7th.

Roundtable Discussion - KITP Small Seminar Room

We will have a roundtable discussion where people will give brief (~5 minute) introductions to what they are currently working on and/or interested in.

Apr. 14th.

Mike Gary - Anomalies I

This week I will be talking about formal aspects of anomalies. Topics to be covered include anomaly forms, descent equations, and other concepts necessary to the understanding of the Green-Schwartz and anomaly inflow methods of anomaly cancellation of importance to string theory.
References:
A. Bilal, 0802.0634
Green Schwartz Witten
J. Polchinski, String Theory vol. 2

Winter 2008

Jan. 16th.

Geoffrey Compere - Introduction to Electric-Magnetic Duality

The program for this week will be an overview of
- First facts about E-M duality
- Schwinger/Zwanziger quantization
- Theta term and Witten effect
- 't Hooft Polyakov monopoles and Julia-Zee dyons
- Montonen-Olive duality conjecture
and motivation to get into N=2 or 4 SYM.

Jan. 30th, Feb. 6th.

Curtis Asplund and Mike Gary - M-theory, Matrix Models, and the BFSS Conjecture

We will discuss the BFSS conjecture relating a matrix quantum mechanics model to light-cone gauge M-theory. In particular, we will attempt to discuss how the M2-brane and other M-theory degrees of freedom are encoded in the matrix model and how the supergravity limit is recovered. Special emphasis will be given to the topic of proving the spectral structure of the matrix model is of the correct form to produce the KK tower of states in M-theory, following the computation of the Witten index performed by Moore, Nekrasov, and Shatashvili and Green and Gutperle.

References:
W. Taylor, hep-th/0101126
G. Moore, N. Nekrasov, S. Shatashvili, hep-th/9803265
M. Green, M. Gutperle, hep-th/9711107
Also, the original paper:
T. Banks, W Fischler, S.H. Shenker, L. Susskind, hep-th/9610043

Feb. 13th, 20th.

Charlie Beil and Raphael Flauger - A-maximization and Z-minimization

Raphael and I will talk about a-maximization and volume minimization, whichÊare explicit checks for the AdS/CFT correspondence.Ê Today we will talk about non-spherical horizons, SCFT's, R-symmetries, the Reeb vector, and introduce toric geometry with volume minimization through the example of the conifold.

References:
Klebanov and Witten, hep-th/9807080 (non-spherical horizons).
Morrison and Plesser, hep-th/9810201 (also non-spherical horizons).
Intriligator and Wecht, hep-th/0304128 (on a-maximization).
Martelli, Sparks and Yau, hep-th/0503183 (on Reeb vectors and Z-minimization).
Butti and Zaffaroni, hep-th/0506232 (on showing a-maximization and Z-maximization are equivalent).
Ê

Feb. 27th, Mar. 5rd.

Richard Eager and Matthew Roberts - Introduction to Seiberg Witten Theory

We give a pedagogical introduction to Seiberg-Witten theory emphasizing the role of anomalies, instantons, and superconformal Ward identities. In the second half, we will be hopefully covering topics such as realization of confinement, the addition of flavor fields, and finding the solutions via M-theory.

References:
Seiberg and Witten, hep-th/9407087 "Electric - magnetic duality, monopole condensation, and confinement in N=2 supersymmetric Yang-Mills theory".
Ê

Mar. 12th, 19th.

Aaron Amsel and Ian Morrison - Introduction to Quantum Loop Gravity

The first talk we'll begin a two part introduction to Quantum Loop Gravity. The talk will have three parts. First we will review canonical gravity using 2nd order variables. We will then introduce the covariant first order formalism. Finally, we will introduce the canonical gravity in the first order formalism. In the second half, we will begin by giving some more details about the derivation of the hamiltonian constraints in the Ashtekar formalism. Then we will discuss some aspects of the quantum theory, including the basic quantization program, the loop representation, and discreteness of area.

References:
A. Ashtekar, "Lectures on Non-Perturbative Canonical Gravity", World Scientific Publishing Co., 1991.
C. Rovelli, "Ashtekar formulation of general relativity and loop-space non-perturbative quantum gravity: a report", Class. Quantum Grav. 8 (1991) 1613-1675.
C. Rovelli, "Loop Quantum Gravity", arXiv:gr-qc/9710008.
Ê

Fall 2007

Oct. 3rd.

Amitabh Virmani - Central Charges in AdS3 Gravity

The symmetry group of AdS5 is SO(4,2) and so is the conformal group of the dual N=4 SYM. However, the symmetry group of the dual theory of AdS3 is not SO(2,2), but the full conformal group in two dimensions. What's more, the dual CFT of AdS3 has a non-trivial central charge. In this talk I will discuss how these details are consistent with the asymptotic symmetries of AdS3. In particular, I will discuss how the conformal algebra and its central extension arises in asymptotically AdS3 gravity.

References:
J. D. Brown and M. Henneaux, "Central Charges in the Canonical Realization of Asymptotic Symmetries: An Example from Three-Dimensional Gravity," Commun. Math. Phys. 104, 207 (1986).

Oct. 10th.

Mauricio Romo - Local supersymmetric extensions of the Poincaré invariant gravity

We present an iterative and constructive process to generate all the local supersymmetric extensions of the odd-dimensional Poincaré invariant gravity. The resulting supersymmetric actions are shown to be Chern-Simons gauge theories for some nontrivial supersymmetric extensions of the Poincaré group with $p-$form ``central charges''. In odd dimensions allowing Majorana spinors, the resulting algebras turn out to be the maximal extensions of the $\mathcal {N}=1$ super Poincaré algebra. In these dimensions, we also derive the supersymmetric extensions of the AdS invariant gravity for the minimal super AdS algebras. A connection between AdS and Poincar\'e supersymmetric theories is achieved through a generalization of the Wigner-Inönü contraction.

Oct 17th.

Maria Jose Rodriguez - Higher dimensional spinning black stuff

A rotating black ring solution in higher dimensions, conjectured to exist but unknown until recently, has a regular horizon of topology S^1 x S^{D-3}. The construction of the approximate solution for an asymptotically flat, neutral, thin rotating black ring in any dimension D \be 5 found by the matching asymptotic expansion method will be presented. Then steps towards qualitatively completing the phase diagram of rotating blackfolds in higher dimensions with a single angular momentum will be discussed.

Oct 24th, 4pm, Small seminar room.

Aaron Amsel - Thermodynamics of General Horizons

The laws of black hole mechanics have been known for roughly three decades and have had great influence on efforts to understand the nature of quantum gravity. More recently, it has been emphasized that analogous laws also hold for more general "causal horizons," such as cosmological or acceleration horizons. After briefly reviewing the 0th, 1st, and 2nd laws, I will focus on the "physical process version" of the first law for bifurcate Killing horizons. I will describe a proof of the physical process first law for quasi-stationary processes, and discuss the conditions under which the proof applies. Some ongoing work related to this subject may be discussed if time permits.
References:
1. T. Jacobson and R. Parentani, "Horizon Entropy", [arXiv:gr-qc/0302099].
2. AA, D. Marolf, and A. Virmani, ``The Physical Process First Law for Bifurcate Killing Horizons," arXiv:0708.2738 [gr-qc].

Oct 31st, 4pm, Small seminar room.

Jorge Rocha - The black hole information loss paradox

The discovery by Hawking in 1974 that black holes evaporate by radiating in a thermal fashion brought with it a conflict: at first sight, the process of black hole formation and consequent evaporation seems to violate a fundamental principle of quantum mechanics, namely unitary evolution. This is the famous information paradox.
In this talk I will review the problem, focusing on the possible information contained in the outcoming radiation, as studied by Don Page. Then I will move on to a more recent proposal by Vachaspati et al. who study the formation and evaporation of black holes by the collapse of spherical thin shells. As seen by an asymptotic observer, the evaporation occurs by emission of non-thermal radiation, even before the formation of an event horizon.
References:
The first part of the talk goes back to the paper by D. Page, hep-th/9306083; There is also a nice book on the subject, called "Black holes, information and the string theory revolution" by Susskind and Lindsey.
For the second part I will rely on the paper by Vachaspati, Stojkovic and Krauss, gr-qc/0609024.

Nov 7th, 4pm Small seminar room.

Daniel Balick - More Dimensions?!? Are you %&#@ing kidding? Supercritical String Theories, the Linear Dilaton, and Cosmology

I will give a pedagogical introduction to supercritical (dimension > 10) string theories. The focus will be on the linear dilaton, emphasizing the timelike linear dilaton and its relation to a very basic cosmology. The latter half of the talk will discuss the stability of perturbations on the linear dilaton background, showing that there exist a class of naively stable cosmological solutions that are indeed supercritical. Additionally, we will discuss the ability to control unstable tachyonic modes in this theory, and touch on the concept of pseudotachyons and their harmlessness.
Why you should care:
An understanding of this subject is a necessary prerequisite to developments in the last 3 years in which a minimal completion in the strong coupling (early time) regime of the timelike linear dilaton theory has been found. This corresponds to a minimal resolution of a cosmological initial singularity, AKA a Big Bang!
Reading:
Suggested pre-reading:
Polchinski, Chapter 2
Polchinski, Section 3.7

Primary Sources:
Polchinski Vol.1
"Supercritical Stability, Transitions, and (Pseudo)tachyons". Ofer Aharony and Eva Silverstein. hep-th/0612031v2
Further Reading if you do care:
"Dimensional Mutation and Spacelike Singularities". Eva Silverstein. hep-th/0510044v2
"New dimensions for wound strings: The Modular transformation of geometry to topology". McGreevy, Silverstein, and Starr hep-th/0612121
"Dimensional-Duality". Green,Ê Lawrence, McGreevy, Morrison, and Silverstein.ÊÊ 0705.0550v3
Recent work of Simeon Hellerman
Recent work of Petr Horava and Cynthia Keeler

Nov 14th, 4pm Small seminar room.

Black Hole Entropy in String Theory

Black holes have entropy S=A/4, A being the area of the event horizon. In a consistent theory of quantum gravity, S=log(N). It turns out that in string theory it is possible to count microstates of certain particularly nice black holes. In this talk I will discuss why we say black holes have entropy, and derive an exact expression for the microscopic entropy of a few important cases. I will try to keep the discussion self-contained, so as to make the subject more accessible.
References:
For a preliminary review of BH thermodynamics, a great review is:
Ross, Black hole thermodynamics http://arxiv.org/abs/hep-th/0502195
Most of the stringy discussion for the early work is best summarized in:
Maldacena, Black Holes in String Theory http://arxiv.org/abs/hep-th/9607235
I'm also pretty sure Polchinski and Becker Becker Schwarz also discuss the canonical results, though likely not in as much detail.

Nov 28th, 4pm Small seminar room.

Ian Morrison - QFT in Eternal de Sitter Space

It has been claimed that the symmetries of de Sitter space are inconsistent with a finite-entropy Hilbert space. This is in direct contradiction to the entropy bound given by the holographic principle. To resolve this contradiction we develop the formalism to carefully treat de Sitter symmetries in perturbative QFT. We show that a consistent treatment of de Sitter symmetries does not lead to a violation of the holographic principle.

References:
S. B. Giddings & D. Marolf, "A global picture of quantum de Sitter space," arXiv:0705.1178 [hep-th]

A. Higuchi, "Quantum linearization instabilities of de Sitter space-time 2," Class. Quant. Grav. 8, 1983 (1991)

N. Goheer, M. Kleban & L. Susskind, "The trouble with de Sitter space," JHEP 0307, 056 (2003) [arXiv:hep-th/0212209]

Dec 5th, 4pm Small seminar room.

Richard Eager - Wave Fronts and D-branes

Hamilton introduced a characteristic function to paramaterize wave fronts in classical optics. After discussing how Einstein, Brillouin, and Keller improved the Bohr-Sommerfeld quantization method using ideas from optics, I will explain how to view Kirillov's character formula as a Fourier transform over wave fronts and its relationship to representations and D-branes.

References:
D-branes and Physics, Sergei Gukov, talks at UCSB and IAS

Dec 12th, 4pm Small seminar room.

Mike Gary - Black Holes in Two Dimensions

Dilaton Gravity coupled to scalar fields in two dimensions provides a particularly simple and controllable environment in which it is possible to study black holes. We will construct a vacuum two dimensional black hole, as well as a black hole formed from collapsing matter, and study the Hawking radiation.

References:
S. B. Giddings, "Quantum Mechanics of Black Holes," hep-th/9412138

N. D. Birrell, P. C. W. Davies, "Quantum Fields in Curved Space," Cambridge Univ. Press

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