String Theory Journal Club
2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025
2018-06-27 (Środa)
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.
2018-06-20 (Środa)
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."
2018-06-13 (Środa)
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.
2018-05-30 (Środa)
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."
2018-05-23 (Środa)
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.
2018-04-24 (Wtorek)
Jakub Jankowski (IFT UW)
Introduction to AdS/CMT, part VI
Introduction to AdS/CMT, part VI
2018-04-10 (Wtorek)
Jakub Jankowski (IFT UW)
Introduction to AdS/CMT, part V
Introduction to AdS/CMT, part V
2018-04-05 (Czwartek)
Jakub Jankowski (IFT UW)
Introduction to AdS/CMT, part IV
Introduction to AdS/CMT, part IV
2018-03-27 (Wtorek)
Jakub Jankowski (IFT UW)
Introduction to AdS/CMT, part III
Introduction to AdS/CMT, part III
2018-03-20 (Wtorek)
Jakub Jankowski (IFT UW)
Introduction to AdS/CMT, part II
Introduction to AdS/CMT, part II
2018-03-13 (Wtorek)
Jakub Jankowski (IFT UW)
Introduction to AdS/CMT
Introduction to AdS/CMT
2018-02-28 (Środa)
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]).
2018-02-07 (Środa)
Przemysław Witaszczyk (Instytut Fizyki UJ)
From p-adic numbers to AdS/CFT
2018-01-31 (Środa)
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.
2018-01-24 (Środa)
Piotr Sułkowski (IFT UW)
The topological vertex
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.
2018-01-17 (Środa)
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.
2018-01-10 (Środa)
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.
2017-12-20 (Środa)
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.
2017-12-13 (Środa)
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.
2017-12-06 (Środa)
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.
2017-11-22 (Środa)
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.
2017-11-15 (Środa)
Paweł Ciosmak (MIMUW & IFT FUW)
Introduction to W-algebras
(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.
2017-10-23 (Poniedziałek)
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.