Quantum Fields and Strings

Displaying 421 - 432 of 725

Three-point functions: SFT, integrability, and perturbative calculations.
April 02, 2013

PIRSA:13040110
Quantum Fields and Strings
Comments on short strings and Wilson loops in AdS/CFT
March 26, 2013

PIRSA:13030111
Quantum Fields and Strings
Evidence for a new particle on the worldsheet of the QCD flux tube

Sergei Dubovsky
New York University (NYU)
March 19, 2013

PIRSA:13030109
Quantum Fields and Strings
Large N Chern-Simons-matter theories and three dimensional bosonization

Ofer Aharony
Weizmann Institute of Science
March 12, 2013

PIRSA:13030106
Quantum Fields and Strings
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

Masahiro Nozaki
University of Chicago
March 05, 2013

PIRSA:13030081
Quantum Fields and Strings
Quantum Computation vs. Firewalls

Daniel Harlow
Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020138
Quantum Information

Quantum Fields and Strings
Wall-Crossing and Quiver Invariants

Piljin Yi
Korea Institute for Advanced Study
February 19, 2013

PIRSA:13020137
Quantum Fields and Strings
Time Crystals

Alfred Shapere
University of Kentucky
February 05, 2013

PIRSA:13020121
Quantum Fields and Strings
How to Fall into a Black Hole

Herman Verlinde
Princeton University
January 29, 2013

PIRSA:13010020
Quantum Fields and Strings
A monodromy defect in the 3d Ising model.

Roberto Pellegrini
National Institute for Nuclear Physics
January 22, 2013

PIRSA:13010106
Quantum Fields and Strings
Superhorizon fluctuations in de Sitter and cosmological spacetimes

Guilherme Pimentel
Universiteit van Amsterdam
January 15, 2013

PIRSA:13010001
Quantum Fields and Strings

Cosmology
Worldsheet form factors in AdS/CFT

Tristan McLoughlin
Trinity College Dublin
January 08, 2013

PIRSA:13010022
Quantum Fields and Strings

Three-point functions: SFT, integrability, and perturbative calculations.
April 02, 2013

PIRSA:13040110
Quantum Fields and Strings
I discuss several recent efforts in relating string field theory calculations of BMN BMN BMN and BMN BMN BPS correlation functions to direct perturbative calculations and integrability-assisted methods. I review the next-to-leading order agreement between strings and perturbation theory in the SO(6) sector, a conjectured extension of the integrability techniques by Escobedo, Gromov, Sever, Vieira from the SU(2) to the full SO(6) sector and agreement with SFT and PT in it at the leading order; finally, I discuss the issue of equating exactly extremal and non-extremal correlators at NLO in the integrability-assisted calculation.
Comments on short strings and Wilson loops in AdS/CFT
March 26, 2013

PIRSA:13030111
Quantum Fields and Strings
In the study of the string/gauge theory duality (AdS/CFT), an important role is played by the relation between local operators and Wilson loops. Perhaps the most well known example is the relation between twist two operators and the light-like cusp Wilson loop. On the string side, the twist two operator is represented by a "long" string (GKP). In this talk I use T-duality to argue that such relation is also natural for "short" strings. I discuss some examples and present a map between the shape of a short string crossing the Poincare horizon and the shape of a corresponding Wilson loop.
Based on arXiv:1212.4886 with Arkady Tseytlin (Imperial College).
Evidence for a new particle on the worldsheet of the QCD flux tube

Sergei Dubovsky
New York University (NYU)
March 19, 2013

PIRSA:13030109
Quantum Fields and Strings
We propose a new approach for the calculation of the spectrum of excitations of QCD flux tubes. It relies on the fact that the worldsheet theory is integrable at low energies. With this approach, energy levels can be calculated for much shorter flux tubes than was previously possible, allowing for a quantitative comparison with existing lattice data. The improved theoretical control makes it manifest that existing lattice data provides strong evidence for a new pseudoscalar particle localized on the QCD fluxtube - the worldsheet axion.
Large N Chern-Simons-matter theories and three dimensional bosonization

Ofer Aharony
Weizmann Institute of Science
March 12, 2013

PIRSA:13030106
Quantum Fields and Strings
I will discuss the conformal theories of N complex scalars or fermions in 2+1 dimensions, coupled to a U(N) Chern-Simons (CS) theory at level k. In the large N limit these theories have a high-spin symmetry, and, as I will review, they are dual to Vasiliev's high-spin gravity theories on four dimensional anti-de Sitter space. Maldacena and Zhiboedov showed that the high-spin symmetry determines the 2-point and 3-point functions of these theories at large N, up to two parameters. The duality to Vasiliev's gravity suggests that there is some mapping between the CS+scalar and CS+fermion theories (when one adds a quartic coupling to the scalar theories, to flow to their "critical fixed point"). We compute explicitly the large N limit of some 2-point and 3-point functions in these theories. We show that the results match with the general results of Maldacena and Zhiboedov, and they are consistent with an equivalence between the critical theory of N scalars coupled to a U(N) CS theory at level k, and the theory of k fermions coupled to a U(k) CS theory at level (N-1/2). We conjecture that this large N equivalence may be an exact duality between the scalar and fermion theories also at finite N, thus providing a bosonization of the fermionic theory. Similar results hold for real scalars (fermions) when U(N) is replaced by O(N).
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench

Masahiro Nozaki
University of Chicago
March 05, 2013

PIRSA:13030081
Quantum Fields and Strings
In this talk, we will describe our recent work. Recently, we focus on the thermodynamical property and time dependence of entanglement entropy. Using holography, we found that the entanglement entropy for a very small subsystem obeys a property which is analogous to the first law of thermodynamics when we excite the system. In relativistic setups, its effective temperature is proportional to the inverse of the subsystem size. This provides a universal relationship between the energy and the amount of quantum information. Moreover, we will propose a new holographic model of local quench and describe some results which we got by using this model. This talk is based on arXiv:1212.1164 [hep-th] and arXiv:1302.5703 [hep-th].
Quantum Computation vs. Firewalls

Daniel Harlow
Massachusetts Institute of Technology (MIT)
February 26, 2013

PIRSA:13020138
Quantum Information

Quantum Fields and Strings
Wall-Crossing and Quiver Invariants

Piljin Yi
Korea Institute for Advanced Study
February 19, 2013

PIRSA:13020137
Quantum Fields and Strings
We start with a one-slide review of the Kontsevich-Soibelman (KS) solution to the wall-crossing problem and then proceed to direct and comprehensive physics counting of BPS states that eventually connects to KS. We also asks what input data is needed for either approaches to produce complete BPS spectra, and this naturally leads to the BPS quiver representation of BPS states and the new notion of quiver invariants.
We propose a simple geometrical conjecture that can segregate BPS states in Higgs phases of the BPS quiver dynamics to those that experience wall-crossing and those that do not, and give
proofs for all cyclice Abelian quivers. We close with explanation of how physics distinguishes two such classes of BPS states.
Time Crystals

Alfred Shapere
University of Kentucky
February 05, 2013

PIRSA:13020121
Quantum Fields and Strings
I consider a class of simple classical systems which exhibit motion in their lowest-energy states and thus spontaneously break time-translation symmetry. Their Lagrangians have nonstandard kinetic terms and their Hamiltonians are multivalued functions of momentum, yet they are perfectly consistent and amenable to quantization. Field theoretical generalizations of these systems may have applications in condensed matter physics and cosmology.
How to Fall into a Black Hole

Herman Verlinde
Princeton University
January 29, 2013

PIRSA:13010020
Quantum Fields and Strings
In this talk I investigate the "firewall argument", that claims that black hole horizons can not be smooth. Using a holographic model of the black hole horizon as a quantum mechanical membrane, I show how to recover the black hole interior as an emergent smooth region of space-time. The reconstruction makes use of the formalism of quantum error correcting codes. I explain why the horizon of very old black holes appears to be singular, and formulate a complementarity principle that resolves this firewall paradox.
A monodromy defect in the 3d Ising model.

Roberto Pellegrini
National Institute for Nuclear Physics
January 22, 2013

PIRSA:13010106
Quantum Fields and Strings
A conformal defect is a d-dimensional geometrical object that breaks the SO(D+1,1) symmetry, of a D-dimensional conformal field theory, down to those transformations that leave the defect invariant i.e. SO(D-d) X SO(d+1,1).
We studied the 3D critical Ising model in presence of a special kind of these defects, a monodromy line defect.
In particular we computed, using Montecarlo simulations, the anomalous dimensions of the lowest dimensional operators living at the defect, as well as correlation functions of operators in the bulk with operators at the defect.
We found a good agreement between our results and the expectations of conformal field theory.
Superhorizon fluctuations in de Sitter and cosmological spacetimes

Guilherme Pimentel
Universiteit van Amsterdam
January 15, 2013

PIRSA:13010001
Quantum Fields and Strings

Cosmology
I will discuss superhorizon fluctuations in de Sitter space. The first part of the talk will focus on computing entanglement entropies of field theories in a fixed de Sitter background. Those computations are done for free theories and also theories with gravity duals. If time permits, I will also discuss superhorizon fluctuations in cosmological backgrounds. In particular, I focus on showing that subhorizon fluctuations can not produce any significant backreaction on superhorizon modes. If those late time effects existed, one in principle could not trust the scale invariant spectrum of inflationary theories to be the source of the spectrum of thermal fluctuations of the CMB.
Worldsheet form factors in AdS/CFT

Tristan McLoughlin
Trinity College Dublin
January 08, 2013

PIRSA:13010022
Quantum Fields and Strings
The study of the worldsheet S-matrix for AdS_5×S^5 strings was a key step in the complete determination of the non-pertubrative planar spectrum of anomalous dimensions for N=4 super-Yang-Mills. To go beyond the spectral problem it is important to consider higher-point worldsheet correlation functions and, as is standard in many integrable models, one approach is the study of form factors. We will discuss a set of consistency conditions appropriate to form factors in the light-cone gauge fixed AdS_5×S^5 string theory. We further discuss the form factors in the weakly coupled dual description, verifying that the relevant conditions naturally hold for the one-loop Heisenberg spin-chain.

Title	Speaker(s)	Date	Talk Type	Info
Three-point functions: SFT, integrability, and perturbative calculations.		2013-04-02	Scientific Series	View details
Comments on short strings and Wilson loops in AdS/CFT		2013-03-26	Scientific Series	View details
Evidence for a new particle on the worldsheet of the QCD flux tube	Sergei Dubovsky	2013-03-19	Scientific Series	View details
Large N Chern-Simons-matter theories and three dimensional bosonization	Ofer Aharony	2013-03-12	Scientific Series	View details
Thermodynamical Property of Entanglement Entropy for Excited States and Holographic Local Quench	Masahiro Nozaki	2013-03-05	Scientific Series	View details
Quantum Computation vs. Firewalls	Daniel Harlow	2013-02-26	Scientific Series	View details
Wall-Crossing and Quiver Invariants	Piljin Yi	2013-02-19	Scientific Series	View details
Time Crystals	Alfred Shapere	2013-02-05	Scientific Series	View details
How to Fall into a Black Hole	Herman Verlinde	2013-01-29	Scientific Series	View details
A monodromy defect in the 3d Ising model.	Roberto Pellegrini	2013-01-22	Scientific Series	View details
Superhorizon fluctuations in de Sitter and cosmological spacetimes	Guilherme Pimentel	2013-01-15	Scientific Series	View details
Worldsheet form factors in AdS/CFT	Tristan McLoughlin	2013-01-08	Scientific Series	View details

Quantum Fields and Strings

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