Found 9 result(s)

24.01.2017 (Tuesday)

Matrix models for the gauge-gravity correspondence

Regular Seminar Nadav Drukker (King's)

15:00 City U.
room B103

The gauge-gravity correspondence identifies a field theory with a gravitational theory. The gravitational theory is weakly coupled when the field theory has large coupling and vice versa, which mostly prevents matching nontrivial results between the two descriptions. I will discuss cases when the field theory calculation can be reduced to a finite dimensional matrix integral, representing some counting problems. I will then evaluate the integral exactly and reexpand the exact result, which is valid for all coupling, at strong coupling. The resulting expression should match a weak coupling gravitational (or string theoretic) calculation and I’ll comment on what is known from that direction.

20.01.2016 (Wednesday)

Polygon Seminar: SUSY field theories and matrix models

Triangular Seminar Nadav Drukker (KCL)

15:00 IC
room LT3 Level 1 Blackett

Matrix models are toy models for quantum field theories. They can be extremely complicated but can also be solved in a variety of ways. In my talk I will discuss general properties of matrix models and their solutions and focus on particular matrix models that arise in the study of 4d SUSY field theories. Those matrix models describe the index of the field theory, counting the number of states of the theory (with + sign for a boson and - for a fermion) and have been known for over 10 years. Though they look very complicated I will show how some simple tricks allow in certain cases to solve those matrix models exactly in terms of elementary functions. My talk will focus on the matrix model calculation and no specialized knowledge of SUSY field theories or indices would be required to follow it.

10.12.2014 (Wednesday)

Localization and quantum AdS_4/CFT_3 holography

Regular Seminar Nadav Drukker (King's College)

14:00 IC
room H139

I will review the calculation of the partition function of 3d supersymmetric field theories on S^3 using the fermi-gas approach to solve the matrix integral. The resulting expression is an Airy function and is valid perturbatively to all orders in 1/N for a wide class of theories (including ABJM). This suggests that a similar formula can be derived by studying quantum gravity on AdS_4. I will explain several of the steps needed to implement this idea and some intriguing results.

22.02.2012 (Wednesday)

Generalized quark antiquark potential and the TBTBA.

Triangular Seminar Nadav Drukker (KCL)

15:30 KCL
room Edmond J Safra Lecture Theatre

Note: Sunil Mukhi's talk was cancelled!

10.02.2011 (Thursday)

(de)Tails of Toda CFT

Regular Seminar Nadav Drukker (IC)

14:00 QMW
room 602

20.10.2010 (Wednesday)

A supermatrix model for ABJM theory

Regular Seminar Nadav Drukker (Imperial)

13:15 KCL
room 423

I will review the matrix model which calculates the partition function of ABJM theory on S3 as well as the expectation value of Wilson loop operators. I will then explain how this matrix model is solved and present the results for these quantities at all values of the couplings. At strong coupling these calculations reproduce the results of supergravity on Ads4 x CP3 and in particular the N to the 3/2 scaling of the free energy of the theory.

04.02.2010 (Thursday)

A supermatrix model for super-Chern-Simons-Matter

Informal Seminar Nadav Drukker (Humboldt)

12:00 IC
room Blackett 741

I will present the 1/2 BPS Wilson loop operator of N=6 super Chern- Simons-matter (ABJM theory) which is dual to the simplest macroscopic open string in AdS4 x CP3. The Wilson loop couples, in addition to the gauge and scalar fields of the theory, also to the fermions in the bi-fundamental representation of the U(N) x U(M) gauge group. These ingredients are naturally combined into a superconnection whose holonomy gives the Wilson loop, which can be defined for any representation of the supergroup U(NlM). Using the localization calculation of Kapustin et al. I will then show that the circular loop is computed by a supermatrix model and discuss the connection to pure Chern-Simons theory with supergroup U(NlM).

18.11.2009 (Wednesday)

N=2 generalized quiver theories, Liouville theory and loop operators

Triangular Seminar Nadav Drukker (Humboldt)

15:00 KCL
room K0.20

A large family of interacting conformal field theories in four dimensions with N=2 supersymmetry was recently constructed by Gaiotto. Each gauge theory is associated to a Riemann surface with certain allowed singularities. In fact, it was proposed by Alday, Gaiotto and Tachikawa that the partition function of these theories (based on SU(2) gauge groups) is equal to correlation function in Liouville theory with central charge c=25. After reviewing these constructions I will turn to a detailed exploration of S-duality using loop operators: Wilson, 't Hooft and dyonic. I will explain the classification and evaluation of arbitrary loops in arbitrary theories and show how they transform into each-other under S-duality.

27.01.2005 (Thursday)

All-genus calculation of Wilson loops using D-branes

Regular Seminar Nadav Drukker (Niels Bohr Institute)

16:00 IC
room H503

The standard prescription for calculating a Wilson loop in the AdS/CFT correspondence is by a string world-sheet ending along the loop at the boundary of AdS. For a multiply wrapped Wilson loop this leads to many coincident strings, which may interact among themselves. In such cases a better description of the system is in terms of a D3-brane carrying electric flux. We find such solutions for the single straight line and the circular loop. The action agrees with the string calculation at small coupling and in addition captures all the higher genus corrections at leading order in alpha'. The resulting expression is in remarkable agreement with that found from a zero dimensional Gaussian matrix model.