Date TBA
Speaker/Title TBA
Abstract
Apr. 1st
Curtis Asplund & Benson Way - Gravitational Plane Waves II
We will
continue the topic started by Benson and I last quarter: deriving the
spectrum of string theory on a plane wave from a certain sector of N=4
Super Yang-Mills theory.
In the talk I'll review the definition of the BMN operators and how their
definition parallels the Penrose limit we took on the gravity side last
time. Then I'll go through the calculation of the anomalous dimensions of
these operators (to all loop order, in the planar limit), which should
correspond to the energies on the string side, and show that they match
the calculation we performed last week. Time permitting, I'll discuss
generalizations and further directions.
Apr. 8th
Richard Eager - Geometry from Quivers
Given a Calabi-Yau threefold, we can associate a 4D N=1 supersymmetric gauge theory on the world-volumes of D3 and D5 branes wrapped on 0 or 2-cycles in the Calabi-Yau. Conversely, given the gauge theory, we can can reconstruct the Calabi-Yau geometry. We will see how this correspondence works for Calabi-Yau threefolds that are ADE fibrations. For ADE fibrations, the correspondence can be formalized as an equivalence of derived categories.
References:
Klebanov and Witten, "Superconformal field theory on threebranes at a Calabi-Yau singularity," hep-th/9807080
Berenstein, "Reverse geometric engineering of singularities," hep-th/0201093
Crawley-Boevey and Holland, "Noncommutative deformations of Kleinian singularities"
Velez and Boer, "Noncommutative resolutions of ADE fibered Calabi-Yau threefolds," arXiv:0806.3177
Apr. 15th
Nikolay Bobev - Attractor mechanism
a pedagogical introduction to the attractor mechanism for supersymmetric black holes.
I'll use a toroidal compactification of M-theory as a simple example which illustrates the attractor mechanism and its consequences for black hole physics. If time permits I'll discuss special geometry and dyonic black holes in four dimensions arising from CY3 compactifications of type IIB.
Apr. 22rd
Idse Heemskerk - Why is weak so strong
I'm going to talk today about 0807.0004 and spend most time on the phenomenological motivation, which is the hierarchy problem.
Apr. 29th
James Sully - Why is weak so strong II
My talk will take a similar perspective to Idse's talk last
week, but this time for a 2D CFT. I will be discussing a paper by
Hellerman (0902.2790) that uses general principles of 2D CFTs to
derive universal properties of 3D quantum gravity.
May 6th
Charles Jess Reidel - Decoherence
Tomorrow I'll be giving an introduction to decoherence and the
quantum-classical transition. The starting point will be the elimination
of the collapse/measurement postulates from quantum mechanics. I'll go
over the crucial problems raised by this elimination and sketch out how
they are solved by decoherence to varying degrees. If time permits, I'll
also describe the physical origin of the Copenhagen postulates.
Review: "Decoherence, einselection, and the quantum origins of the
classical". W. H. Zurek. quant-ph/0105127
May 13th
Jonathan BenTov - What is dark matter?
The question is ``What is dark matter?" and the answer is ``I don't know, and neither does anyone else." However, we do know a few things, and it is reasonable to expect that the answer lies in particle physics beyond the standard model. The general subject of dark matter particle phenomenology is currently very active and very open, so time will permit only an introduction. I will give a brief overview of the following topics: why we think there's something else out there, what we're doing to try to find out what it is, and only a glimmer of the fanciful proposals put forth by particle physicists to understand the data.
Review: G. Gelmini, "Search for Dark Matter," http://arxiv.org/abs/0810.3733v1
May 20th
Ian Morrison - a rigorous definition of quantum field theory in curved spacetime
While QFT in CST is fairly well understood in the special cases of free fields and/or spacetimes with a large amount of symmetry, this is not so for the general case of interacting fields in arbitrary curved spacetimes. The Wightman axioms which provide the most formal and rigorous definition of QFT in flatspace rely heavily Poincare symmetry. Hollands and Wald have been hard at work "generalizing" these axioms. This is interesting because here "generalizing" really means thinking about QFT differently, not simply dressing up the Wightman axioms in covariant clothing. While the subject is a little formal, I will try to place an emphasis on the practical, i.e. how do you actually compute something, and on gaining new insight on QFT. Most importantly, I realize many of you may be a little out of it from attending/giving talks, so I will try to keep the talk light and coherent.
A good piece of warm-up reading, should you find the time between now and then, is Hollands and Wald (http://arxiv.org/abs/0805.3419).
May 27th
Mauricio Romo - Singularities from quivers
I'll be talking about how to engineer singularities from quiver
gauge theories in 4d. This is can be done using some tools from algebraic
geometry. I'll mainly do examples, say the q deformed SYM and the A_{n}
singularity. If time allows I'll discuss why this computation of the
moduli space cannot be applied straightforwardly for 3d gauge theories
using as example ABJM. References:
hep-th/0005087
0808.0912 [hep-th]
Jun. 3rd
Mike Mulligan - long strings and black holes
I'll talk about the statistical description of 5D black holes formed from coincident D1-D5 systems with momentum along the direction shared the two different types of branes. We'll find that the "long string" configuration entropically dominates the naive configuration of many branes singly wrapping the shared compact direction. It is possible to see this using simple thermodynamic arguments.
Jun. 8th
GUEST LECTURE: Aaron Bergman - K theory
Lectures on K-theory (and its relation to D-branes) courtesy of Aaron Bergman.
Jan. 14th
Matthew Roberts - Perturbative Matrix Models for Nonperturbative Gauge Theories
We all know that in N=1 super-Yang-Mills, there are N distinct vacua. I will explain how these are in fact parameterized by a gluino condensate. In an effort to describe the low-energy effective theory in terms of these gluino bilinear, we will explore an alternative construction of the nonperturbative quantum effective superpotential in terms of a large N, perturbative result of a Matrix model (despite no large-N limit being taken in the field theory!)
Ref.s:
Dijkgraaf & Vafa, hep-th/0208048 and hep-th/0206255
Cachazo, Douglas, Seiberg and Witten, hep-th/0211170
Jan. 21st
Richard Eager - Perturbative Matrix Models for Nonperturbative Gauge Theories II
I will take off from Matt's introduction to N = 1 Super Yang-Mills and show how we can compute non-perturbative quantities in a closely related gauge theory. Remarkably the non-perturbative quantities in the gauge theory will be determined by a perturbative matrix model. No background in matrix models will be assumed. Special emphasis will be given to the analogies between matrix models and string theory.
We will be loosely following the Dijkgraaf-Vafa's trilogy:
[1] hep-th/0206255
[2] hep-th/0207106
[3] hep-th/0208048
Jan. 28th
Ahmed Almuhairi - diffeomorphism invariant observables
I will be presenting on the construction and interpretation of
diffeomorphism invariant observables in low energy effective quantum
gravity. These observables are constructed as integrals over spacetime, in
analogy to gauge invariant observables in Yang-Mills theory via traces. I
will then consider two examples, the Z & Phi.Psi^2 -models, of localizing
these operators and retrieving local physics.
I will be following Giddings, Marolf, and Hartle's paper:
hep-th/0512200
Feb. 4th
Ian Morrison - diffeomorphism invariant observables II
This talk will focus on observables in perturbative gravity about cosmologies with compact cauchy surfaces, and in particular de Sitter. In this setting the gravitational constraints require states and observables to be invariant under the isometries of the background spacetime. The goal of the talk will be to show how one can recover -- approximately -- the local observable algebra of local quantum field theory from non-local observables satisfying these constraints.
If you would like to read up ahead of time, two good refrences are 1) the paper discussed last week by Gidding, Hartle, and Marolf (2005), and 2) the more recent paper by Giddings and Marolf (2008).
Feb. 11th
Idse Heemskerk - introduction to AdS/CFT
we will discuss a paper which is about matching up the contributions of different supergravity diagrams to the dilaton axion four point function with contributions to the OPE on the CFT side.
D'Hoker and Freedman review of AdS/CFT:
hep-th/0201253
D'Hoker, Mathur, Matusis and Rastelli paper:
hep-th/9911222
Feb. 18th
James Sully - introduction to AdS/CFT II
we'll be continuing our short and all too rapid introduction to
AdS/CFT. Hopefully on completing that, we will have sufficient time to
discuss the relationship between conformal partial waves in the CFT
operator product expansion and AdS supergravity exchange diagrams. This
relationship will demonstrate a non-trivial check of AdS/CFT across the
weak/strong coupling regimes.
Feb. 25th
Mauricio Romo - an introduction to
WZW models.
The topics that will be covered are (tentatively, as time
allows): some classical aspects, arising of affine currents, primary
fields, their use as string action, gauged WZW models, some topics on
affine Kac Moody algebras and their representations, partition function of
WZW models. Some references:
P. Difrancesco, P. Mathieu and D. Senechal, Conformal Field Theory (chaps.
13,14,15)
Mar. 4th
Mauricio Romo - an introduction to
WZW models II.
we will continue with the introduction to WZW models. Tomorrow I
will focus in the uses of wzw models as worldsheet action for string
theory, and properties of their gauged counterparts. Some references:
E. Witten, Comm. Math. Phys. 144, 182-212 (1992)
A. A.Tseytlin, hep-th/9301015
A. A. Tseytlin, hep-th/9302083
Mar. 11th
Curtis Asplund - Gravitational Plane Waves
I will describe the physics of
gravitational plane waves, plane waves as (Penrose) limits of AdS spaces,
string theory on plane-wave backgrounds, and how this physics emerges from
the dual quantum field theory, specifically N = 4, d = 4 SYM.
In Part 1 on the talk we will spend most the time on
describing the geometry of plane waves, the (Penrose) limiting process,
and solving the spectrum of the string in a plane wave background (in
light-cone gauge).
In Part 2, we will focus mainly on the dual gauge theory, describe the
sector of the theory dual to the plane-wave limit, and show how the
spectrum of the string in that background can be recovered from the
spectrum of the appropriate operators (The BMN operators).
References:
Berenstein, Maldacena, and Nastase. ``Strings in flat space and pp waves
from ${\cal N}=4$ Super Yang Mills" http://arxiv.org/abs/hep-th/0202021
This is the paper that made the initial breakthrough of identifying the
correct dual operators to the modes of the string on a plane wave, and is
sti
ll a good reference.
A good review from a little bit later is:
Sadri and Sheikh-Jabbari ``The Plane-Wave/Super Yang-Mills Duality"
http://arxiv.org/abs/hep-th/0310119
Oct. 3rd
Curtis Asplund - Black Hole War
We will discuss some of the controversies of black hole physics. The talk
is inspired by, and the title stolen from, Lenny Susskind's recent book
_The Black Hole War: My Battle with Stephen Hawking to Make the World Safe
for Quantum Mechanics_. The central question is the "information paradox:"
is information lost after it falls into a black hole? This battle to
answer this question, finally in the negative, is a central part of the
story of high energy theoretical physics, culminating in the celebrated
holographic principle and the AdS/CFT correspondence. Other topics we'll
explore are black hole complementarity, the mixing of thermal and quantum
fluctuations near a BH horizon, and the scrambling of information by black
holes.
Sources:
_The Black Hole War_, by Leonard Susskind, Little Brown and Company 2008.
"Particle Creation by Black Holes," Stephen Hawking, 1975 (what got it all
started)
"Fast Scramblers," Susskind and Sekino arxiv.org/abs/0808.2096 (Lenny's
recent work)
"Resource Letter BH-2: Black Holes" Marolf and Gallo,
arxiv.org/abs/0806.2316 (Useful bibliography by our own Don)
"Small Ads Black Holes from SYM" Asplund and Berenstein,
arxiv.org/abs/0809.0712 (shameless self-advertisement)
Oct. 10th
Richard Eager - Supersymmetry and Index Theory: Introduction and Applications
We review Witten's celebrated interpretation of Morse theory in terms of supersymmetric quantum mechanics. After generalizing from quantum mechanics to (2,2) 2D superconformal field theories we will encounter a corresponding generalized index, the elliptic genus. Modularity properties of superconformal field theory severely restrict the possible values of the elliptic genus. As an illustrative example we will explicitly determine what these constraints imply for the topology of a Calabi-Yau fourfold. If time permits we will show how the same constraints follow from M-theory.
Oct. 17th
Mike Gary - AdS/CFT and the S-Matrix
I will be talking about my recent and ongoing work with Steve Giddings and
João Penedones on recovering the flat-space S-Matrix from AdS/CFT.
Particular attention will be given to understanding the role of wave
packets in constructing the S-Matrix, wave packet evolution, and integral
localization. Many of the subjects covered in the talk are also relevant
for understanding scattering in flat space, and in fact, building flat
space intuition will be a large part of the discussion.
Oct. 24th
Eric Perkins - Gravity, Gauge Fields, Gerbils
The MacDowell-Mansouri formulation of relativity treats gravitation as a
gauge theory by packaging the spin connection and vielbein together into a
single gauge field. This trick has an interpretation in terms of Cartan
geometry, and thereby yields a picture of the MM gauge connection as
describing a homogeneous space `rolling without slipping' on a spacetime.
Primary references:
gr-qc/0611154
Phys. Rev. Lett. 38, n.14 (1977)
Nov. 1st
Idse Heemskerk - BS about bound states
I'll discuss the treatment of bound states in quantum field theory through the Bethe-Salpeter equation.
An interesting application is 't Hooft's large N model for mesons.
Nov. 5th
Mauricio Romo- Reverse geometric engineering of singularities
D-branes in singular spaces admits a description in terms of
supersymmetric conformal theories in the worldvolume of the brane. This
connection between singular geometries and field theories is called
geometric engineering. I will show a procedure to recover the geometry
from the moduli space of vacua of a given susy field theory by some
algebraic procedure.
Some references:
D. Eisenbud, Commutative algebra with a view toward algebraic geometry
D. Berenstein, hep-th/0201093
D.Berenstein, V. Jejjala and R. Leigh, hep-th/0005087
Nov. 12th
Ian Morrison - Small physics in really big de Sitter
A long-standing problem in quantum gravity is the recovery of local physics from diffeomorphism-invariant observables. Diff-invariant observables should not only reduce to local observables but also reproduce the algebra of local observables in the limit $ m_{Planck} \to 0 $. One playground for studying such diff-invariant observables is de Sitter space. In this talk I hope to discuss 1) what exactly local physics is in de Sitter, and 2) the recovery of local physics from diff-invariant quantities.
Possibly useful references:
S. B. Giddings, D. Marolf and J. B. Hartle,
``Observables in effective gravity,''
Phys. Rev. D 74, 064018 (2006)
[arXiv:hep-th/0512200].
S. B. Giddings and D. Marolf,
``A global picture of quantum de Sitter space,''
Phys. Rev. D 76, 064023 (2007)
[arXiv:0705.1178 [hep-th]].
Nov. 19th
Guest Speaker Chris Justus - new CDF results possibly (isn't) showing new physics
Recently, a paper [arXiv:0810.5357v1 [hep-ex] 29 Oct 2008] published by the CDF collaboration announced an excess of dimuon events, with large impact parameters, which they claim cannot be explained given their understanding of the CDF II detector, trigger and event reconstruction. I will describe ways muons with large impact parameters can be faked, the methods they used to arrive at their conclusion and discuss possible problems in their explanations.
Nov. 26th
James Sully - 2+1-dimensional gravity
I will give a general introduction to gravity in three dimensions, discuss
how it can be interpreted as a gauge theory, and stress the importance of
BTZ black holes. I will then motivate Witten's proposal for a dual
boundary CFT to pure 3D quantum gravity, discuss its assumptions and
possible shortcomings, and hopefully have time to mention alternate
formulations.
Useful references are:
S. Carlip, gr-qc/0503022
S. Carlip, gr-qc/9503024
Brown and Henneaux, Commun.Math.Phys.104:207-226,1986
E. Witten, Nucl.Phys.B311:46,1988
E. Witten, arXiv:0706.3359 [hep-th]
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
Apr. 21st.
Richard Eager - Anomalies II
We continue last week's discussion of anomalies. Special emphasis will be
given to uncovering the geometric origin of the descent equations. We
will review the Green-Schwarz mechanism and give applications to string
dualities.
References:
[1] Luis Alvarez-Gaume, Paul H. Ginsparg , "The Topological Meaning of
Nonabelian Anomalies"
Nucl.Phys.B243:449,1984.
[2] A. Bilal, 0802.0634
[3] Green, Schwarz, Witten Vol. II
May 1st.
Matthew Roberts - Superconductivity and AdS/CFT
We will begin with a review of BCS superconductivity: the discovery of the cooper instability, the dynamics of cooper pairs, and the hubbard-stratonovich transformation leading to the ginsburg-landau effective theory. We will then move on to discussing the basics of finding superconductivity in CFTs by way of the AdS/CFT correspondence. The talk is designed to be introductory, as most HEP/Gravity students never take the condensed matter courses that cover BCS theory in detail, despite it being a beautiful example of the power of field theoretic techniques and RG. It should be comprehensible (in part?) to both condensed matter theorists and HEP/gravity students, hopefully without being boring to both.
Ref.s:
R. Shankar, Renormalization-group approach to interacting fermions
J. Polchinski, Effective Field Theory and the Fermi Surface
Any good modern condensed matter field theory text, e.g.
Condensed Matter Field Theory, Altland and Simons
Sean A. Hartnoll, Christopher P. Herzog, Gary T. Horowitz Building an AdS/CFT superconductor.
My 5th.
Curtis Asplund - Inflation for String Theorists
Abstract: I'll present a review of inflation (including some of its
varieties) and some of the ideas for and problems with embedding it in
string theory.
References: "Cosmology for String Theorists," by Carroll hep-th/0011110
"String Cosmology: A Review" by McAllister and Silverstein hep-th 0710.2951
May 12th.
Dan Balick - De Sitter Vacua and Inflation in String Theory
As a follow up to Curtis' discussion of inflation last week, I will
talk about the interface between string theory and inflation. We will
discuss, in particular, KKLT moduli fixing and metastable De Sitter,
and the KKLMMT model of stringy inflation. This talk is intended to
be and interesting introduction to cosmological model building in
string theory, discussing one of the first calculations models of this
kind.
References:
De Sitter vacua in string theory. hep-th/0301240
Towards inflation in string theory. hep-th/0308055
Additional Resources for Related Topics:
Hierarchies from fluxes in string compactifications. hep-th/0105097
(A)dS backgrounds from asymmetric orientifolds. hep-th/0106209
De Sitter space in noncritical string theory. hep-th/0205316
and many more...
May 19th.
Aaron Amsel - Quantum Probes of Spacetime Singularities
In this week's journal club, I will discuss an old paper by
Horowitz and Marolf on quantum probes of spacetime singularities
[gr-qc/9504028]. In this work, the authors propose a condition for a
quantum theory to be "singular," and show that there are static spacetimes
with timelike curvature singularities that appear nonsingular quantum
mechanically. The talk will include a brief review of classical
singularities in GR, an introduction to self-adjoint extensions of
symmetric operators, and application of these ideas to some example
spacetimes.
June 9th.
Ian Morrison - Lambda, alternative IR gravity, and the trace anomaly
The cosmological constant has driven research into IR modifications of gravity. I will introduce one such proposal based upon the quantum trace anomaly.
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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