String Theory Journal Club
2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025
2020-07-15 (Wednesday)
room 5.42, Pasteura 5 at 15:00 
Edgar Shaghoulian (Cornell)GQFI-WST Virtual Seminar: Islands in asymptotically flat 2d gravity
2020-07-08 (Wednesday)
join us at 15:00
David Kolchmeyer (Harvard)GQFI-WST Virtual Seminar: Entanglement Entropy in Jackiw-Teitelboim Gravity
2020-06-24 (Wednesday)
room 5.42, Pasteura 5 at 15:00
Arjun Kar (U. Penn)GQFI-WST Virtual Seminar: Geometric secret sharing in a model of Hawking radiation
2020-05-27 (Wednesday)
join us at 15:00
Ki-Seok Kim (POSTECH, Pohang)GQFI-WST Virtual Seminar: "Emergent holographic dual effective field theory as a mean-field theory with all-loop quantum corrections in the large N limit."
2020-05-20 (Wednesday)
room 5.42, Pasteura 5 at 16:00
Nick Hunter-Jones (IQI, Perimeter)GQFI-WST: "Models of quantum complexity growth"
https://mpi-aei.zoom.us/j/99064635917
The quantum complexity of a unitary or state is defined as the size of the shortest quantum computation that implements the unitary or prepares the state. The notion has far-reaching implications spanning computer science, quantum many-body physics, and high energy theory. Complexity growth in time is a phenomenon expected to occur in holographic theories and strongly-interacting many-body systems more generally, but explicitly computing the complexity of a given state or unitary is notoriously difficult. By considering an ensemble of systems, and establishing a rigorous relation between complexity and unitary designs, we will prove statements about complexity growth in various models. Specifically, we prove a linear growth of complexity in random quantum circuits, using a recent result about their design growth. Link: https://mpi-aei.zoom.us/j/99064635917. GQFI-WST is a common online seminar series organized by "Gravity, Quantum Fields and Information" (GQFI) group at the Max Planck Institute (Potsdam) and String Theory group at the University of Warsaw (WST).
2020-05-13 (Wednesday)
join us at 15:00
Nabil Iqbal (IFT UW)GQFI-WST: "Toward a 3d Ising Model with a weakly coupled string dual"
https://mpi-aei.zoom.us/j/91981837516
It has long been expected that the 3d Ising model can bethought of as a string theory, where one interprets the domain wallsthat separate up spins from down spins as two-dimensional stringworldsheets. I will revisit this "string theory" from the modern pointof view of higher form symmetries. The usual Ising Hamiltonian measuresthe area of these domain walls; as there is no explicit dependence onthe genus of the domain walls, it can be thought of as a string theorywith string coupling equal to unity. I discuss how to add new localterms to the Ising Hamiltonian that further weight each spinconfiguration by a factor depending on the genus of the correspondingdomain wall, resulting in a new 3d Ising model that has a tunable barestring coupling. I will use a combination of analytical and numericalmethods to analyze the phase structure of this model as this stringcoupling is varied. I will also describe statistical properties of thetopology of worldsheets and speculate on the prospects of using this newdeformation at weak string coupling to find a worldsheet description ofthe 3d Ising transition. Link: https://mpi-aei.zoom.us/j/91981837516. GQFI-WST is a common online seminar series organized by "Gravity, Quantum Fields and Information" (GQFI) group at the Max Planck Institute (Potsdam) and String Theory group at the University of Warsaw (WST).
2020-03-10 (Tuesday)
room 5.42, Pasteura 5 at 11:00
Paweł Caputa (IFT UW)Complexity in Quantum Field Theories
I will talk about the program of quantifying "Complexity" in quantum field theories. After some background and motivation I will discuss recent results in two-dimensional conformal field theories and their possible implications for the program and AdS/CFT.
2020-03-03 (Tuesday)
room 5.42, Pasteura 5 at 11:00
Piotr Kucharski (Caltech & IFT UW)Discussion on arXiv:1910.06193
Organizational meeting and a discussion on arXiv:1910.06193.
2020-02-05 (Wednesday)
room 5.42, Pasteura 5 at 14:30
Dmitry Noshchenko (IFT UW)Quivers and combinatorics of Nahm equations, part III
We discuss algebraic Nahm equations and their resultants from the combinatorial point of view, using the machinery developed for mixed resultants. Such equations describe semi-classical limit of the quiver partition function (should be not confused with ODE Nahm equations), which encodes motivic Donaldson-Thomas invariants of the quiver, and is in fact q-hypergeometric series of special form. Specializations of such q-series may lead to various dualities between quivers, knots and topological strings.
2020-01-28 (Tuesday)
room 5.42, Pasteura 5 at 14:30
Dmitry Noshchenko (IFT UW)Quivers and combinatorics of Nahm equations, part II
We discuss algebraic Nahm equations and their resultants from the combinatorial point of view, using the machinery developed for mixed resultants. Such equations describe semi-classical limit of the quiver partition function (should be not confused with ODE Nahm equations), which encodes motivic Donaldson-Thomas invariants of the quiver, and is in fact q-hypergeometric series of special form. Specializations of such q-series may lead to various dualities between quivers, knots and topological strings.
2020-01-21 (Tuesday)
room 5.42, Pasteura 5 at 14:30
Dmitry Noshchenko (IFT UW)Quivers and combinatorics of Nahm equations, part I
We discuss algebraic Nahm equations and their resultants from the combinatorial point of view, using the machinery developed for mixed resultants. Such equations describe semi-classical limit of the quiver partition function (should be not confused with ODE Nahm equations), which encodes motivic Donaldson-Thomas invariants of the quiver, and is in fact q-hypergeometric series of special form. Specializations of such q-series may lead to various dualities between quivers, knots and topological strings.
2019-11-05 (Tuesday)
room 5.42, Pasteura 5 at 14:30
Shi Cheng (IFT UW)From JT gravity to a matrix model
Correlation function of JT gravity could be formulated as the volume of moduli space of Riemann surface where the gravity lives. Mirzakhani’s recursion relation then join the story and give rise to the decomposition of Riemann surface along geodesics. Since Mirzakhani’s recursion is the Eynard’s topological recursion after Fourier transformation, JT gravity can represented as a matrix model, and the correlation function of JT gravity corresponds to the resolvent function in this matrix model. The W_{0,1} and W_{0,2} and the spectral curve, as initial data for topological recursion, could be derived from physics. We will also discuss the topological recursion for both supersymmetric JT gravity. The (arXiv) references are 1907.03363, 1903.11115, 0705.3600, 0601194.
2019-10-29 (Tuesday)
room 5.42, Pasteura 5 at 14:30
Carlos Perez (IFT UW)Computing the spectral action for even-dimensional matrix geometries, part II
Matrix geometries were introduced by J. Barrett in the spirit of Connes’ Noncommutative Geometry. As the name suggests, matrix geometries are modeled by finite dimensional algebras, which with additional structure form finite spectral triples (in some sense, an approximation to smooth manifolds). A path-integral quantization approach of these finite spectral triples turns out to lead to multi-matrix random models, the model in question being determined by the so-called spectral action. We present formulae for the spectral action of even-dimensional matrix geometries (as part of ongoing work).
2019-10-24 (Thursday)
room 5.42, Pasteura 5 at 11:00
Carlos Perez (IFT UW)Computing the spectral action for even-dimensional matrix geometries
Matrix geometries were introduced by J. Barrett in the spirit of Connes’ Noncommutative Geometry. As the name suggests, matrix geometries are modeled by finite dimensional algebras, which with additional structure form finite spectral triples (in some sense, an approximation to smooth manifolds). A path-integral quantization approach of these finite spectral triples turns out to lead to multi-matrix random models, the model in question being determined by the so-called spectral action. We present formulae for the spectral action of even-dimensional matrix geometries (as part of ongoing work).
2019-10-16 (Wednesday)
room 5.42, Pasteura 5 at 11:00
Paweł Ciosmak (MIMUW & IFT UW)Super quantum Airy structures
Quantum Airy structures are a reformulation and generalisation of the topological recursion. However, satisfying extension of the topological recursion for the supersymmetric theories is unknown. I will introduce supersymmetric analog of the Quantum Airy structures, discuss examples and some possible directions for the future research.