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String Theory Journal Club

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Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:00

Vivek Singh (Indian Institute of Technology)

Arborescent knot/link invariant and multi-boundary entanglement within Chern Simons framework

First, I will review the method of obtaining a polynomial form for arborescent knot/link invariants. Then, I will discuss the recent developments on multi boundary entanglement entropy within Chern Simons field theoretic framework. Particularly, I will highlight the interesting relation between the volume of hyperbolic link complements to non-zero entanglement negativity and present my numerical computation for well known three component Borromean rings.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:00

Tomasz Taylor (Northeastern University)

Strings on Celestial Sphere

A new paper of the speaker will be presented https://arxiv.org/abs/1806.05688, whose abstract reads: "We transform superstring scattering amplitudes into the correlation functions of primary conformal fields on two-dimensional celestial sphere. The points on celestial sphere are associated to the asymptotic directions of (light-like) momenta of external particles, with the Lorentz group realized as the SL(2,C) conformal symmetry of the sphere. The energies are dualized through Mellin transforms into the parameters that determine dimensions of the primaries. We focus on four-point amplitudes involving gauge bosons and gravitons in type I open superstring theory and in closed heterotic superstring theory at the tree-level."

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:00

Petr Vasko (IFT UW)

Scaling dimensions of Coulomb branch operators for 4d N=2 SCFTs

I will briefly introduce superconformal algebras and a few key aspects of their unitary representations. Then I specialize to 4d N=2 superconformal field theories. The main purpose of this talk is to review the spectrum of scaling dimensions of Coulomb branch operators for this class of theories (based on 1801.06554 and 1801.04542). With this knowledge at our disposal we will tackle questions like how many Lagrangian theories there are among all SCFTs (in an asymptotic sense that will be explained and moreover restricted to this special subsector of operators) and more.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:00

Miłosz Panfil (IFT UW)

Far from equilibrium energy flow in quantum critical systems

I will talk about the paper "Far from equilibrium energy flow in quantum critical systems" by M. J. Bhaseen, Benjamin Doyon, Andrew Lucas, and Koenraad Schalm (https://arxiv.org/pdf/1311.3655.pdf). The abstract of this paper reads: "We investigate far from equilibrium energy transport in strongly coupled quantum critical systems. Combining results from gauge-gravity duality, relativistic hydrodynamics, and quantum fieldtheory, we argue that long-time energy transport occurs via a universal steady-state for any spatial dimensionality. This is described by a boosted thermal state. We determine the transport properties of this emergent steady state, including the average energy flow and its long-time fluctuations."

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:00

Dmitry Noshchenko (IFT UW)

W-algebras and the topological recursion, revised

We present some interesting constructions of W algebras of type A,D by the topological recursion (TR) and relate them to higher Airy structures. This suggests a new, more combinatorial view on W_r modes itself. We also consider "twists", such as breaking Lie algebra property and using the TR without branching on a branched curve at a general point. arXiv references: 1203.3414, 1412.3286, 1603.00073, 1703.03307, 1804.07417.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 15:00

Jakub Jankowski (IFT UW)

Introduction to AdS/CMT, part VI

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 16:00

Jakub Jankowski (IFT UW)

Introduction to AdS/CMT, part V

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 13:00

Jakub Jankowski (IFT UW)

Introduction to AdS/CMT, part IV

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 16:00

Jakub Jankowski (IFT UW)

Introduction to AdS/CMT, part III

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 16:00

Jakub Jankowski (IFT UW)

Introduction to AdS/CMT, part II

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 16:00

Jakub Jankowski (IFT UW)

Introduction to AdS/CMT

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Helder Larraguivel (IFT UW)

Three-point functions in N=4 SYM and spin chains

In the last couple of decades, a lot of progress has been done in the computation of three-point funcitons in N=4 SYM. This is due to Minahan and Zarembo (hep-th/0212208), who noticed that computing anomalous dimensions is equivalent to the diagonalization of the Hamiltonian for certain spin chains. First I will discuss the computation of the structure constant at weak coupling and show that the result can be recast as a sum over partitions of the rapidities of the magnons. Then, I introduce a non-perturbative framework, called the “hexagon approach” to determine the structure constants. The content from the talk is based on a nice set of lecture notes by S. Komatsu (1710.03853 [hep-th]).

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Przemysław Witaszczyk (Instytut Fizyki UJ)

From p-adic numbers to AdS/CFT

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Piotr Sułkowski (IFT UW)

The topological vertex, part II

I will review what "The topological vertex" is, and then we can (try to) discuss more recent developments. Relevant publications are: 1. the original paper:https://arxiv.org/abs/hep-th/0305132; 2. (one version of the) refined vertex:https://arxiv.org/abs/hep-th/0701156; 3. recent work by Gaiotto and Rapcak on W-algebras and the topological vertex: https://arxiv.org/abs/1703.00982; 4. the last paper by Omar and Masahide: https://arxiv.org/abs/1801.04943.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Piotr Sułkowski (IFT UW)

The topological vertex

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Ehsan Hatefi (IFT UW)

Veneziano amplitude

In this journal club we present the Veneziano amplitude within full detail. If time permits we try to go on to discuss more general superstring scattering amplitudes which involve one or two closed string states in the bulk, and effectively explore their effective actions to all orders in alpha-prime.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Ehsan Hatefi (IFT UW)

Veneziano amplitude

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:00

Piotr Kucharski (Uppsala University)

Extremal augmentation polynomials

This talk and discussion will focus on geometric picture (in the language of knot contact homology) behind extremal A-polynomials introduced by Garoufalidis, Sulkowski and the speaker. The project is still in progress (together with Diogo, Ekholm and Maydanskiy) so a lot of interactions and informal atmosphere are expected.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Ehsan Hatefi (IFT UW)

D-brane effective actions in string theory and their alpha-prime corrections

We would like to talk about all kinds of effective actions in Type IIA, IIB superstring theories, including DBI, Chern-Simons, more importantly new Wess Zumino actions.We also provide a comprehensive explanations even for D-brane anti-D-brane systems as well as BPS branes. Along those actions, we also introduce various new techniques for mathematicians/string theorists for which getting the exact and final form of the world sheet integrals up to five point mixed closed-open amplitudes to all orders will be presented.Eventually we make various remarks on how to derive without any ambiguity all order alpha-prime corrections to all type II effective actions. If time permits, we also talk about some of the recent applications for these effective actions.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Dmitry Noshchenko (IFT UW)

W-algebras from the ABCD of topological recursion

We describe W-algebras, attached to a spectral curve locally near its branch points. The construction is determined by Bouchard-Eynard topological recursion, and the resulting algebra of differential operators is presented. The following cases are considered: r-Airy curve x=y^r and its deformation, parametrized by KdV-r times.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Paweł Ciosmak (MIMUW & IFT FUW)

Introduction to W-algebras, part II

(Quantum) W-algebras are a generalization of the Virasoro algebra, which appeared in the study of the classification of 2-dim rational conformal field theories. In my talk I will define those algebras, give some examples and show how they can be obtained using coset construction and Drinfeld-Sokolov reduction.

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 12:15

Paweł Ciosmak (MIMUW & IFT FUW)

Introduction to W-algebras

Zapraszamy do sali 5.42, ul. Pasteura 5 o godzinie 14:00

Jakub Jankowski (IFT UW)

Real time dynamics and phase separation in a holographic first order phase transition

I will present the fully nonlinear time evolution of a holographic system possessing a first order phase transition. The initial state is chosen in the spinodal region of the phase diagram, and includes an inhomogeneous perturbation in one of the field theory directions. The final state of the time evolution shows a clear phase separation in the form of domain formation. The results indicate the existence of a rich class of inhomogeneous black hole solutions.