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Seminars at

Found at least 20 result(s)

22.11.2021 (Monday)

Lonti: Duality Symmetry in String Theory and Field Theory

Regular Seminar Chris Hull (IC)

at:
10:00 Other
room Online
abstract:

Lonti Autumn 2021 Series: Lecture 5. Live Tutorial. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom.

15.11.2021 (Monday)

Lonti: An Introduction to Observables in Gauge Theories

Regular Seminar Nadav Drukker (KCL)

at:
10:00 Other
room Online
abstract:

Lonti Autumn 2021 Series: Lecture 4. Live Tutorial. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom.

15.11.2021 (Monday)

Lonti: Duality Symmetry in String Theory and Field Theory

Regular Seminar Chris Hull (IC)

at:
10:00 Other
room Youtube
abstract:

Lonti Autumn 2021 Series: Lecture 5. Release of Recorded Lecture.

08.11.2021 (Monday)

Lonti: CPT symmetry in Quantum Field Theory

Regular Seminar Andreas Fring (City)

at:
10:00 Other
room Online
abstract:

Lonti Autumn 2021 Series: Lecture 3. Live Tutorial. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom.

08.11.2021 (Monday)

Lonti: An Introduction to Observables in Gauge Theories

Regular Seminar Nadav Drukker (KCL)

at:
10:00 Other
room Youtube
abstract:

Lonti Autumn 2021 Series: Lecture 4. Release of Recorded Lecture.

01.11.2021 (Monday)

Lonti: (Holographic) Fermi surfaces

Regular Seminar David Vegh (QMUL)

at:
10:00 Other
room Online
abstract:

Lonti Autumn 2021 Series: Lecture 2. Live Tutorial. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom. Abstract: In this lecture, we present a few elementary facts about Fermi surfaces, then discuss how to find interesting ``non-Fermi liquids'' via the AdS/CFT correspondence. We study different backgrounds (e.g. AdS, BTZ, and Reissner-Nordstrom), and the wave-equation of probe fields on top of these geometries. We discuss how to compute boundary two-point functions by solving the bulk equations and then explore the results.

01.11.2021 (Monday)

Lonti: CPT symmetry in Quantum Field Theory

Regular Seminar Andreas Fring (City)

at:
10:00 Other
room Youtube
abstract:

Lonti Autumn 2021 Series: Lecture 3. Release of Recorded Lecture.

28.10.2021 (Thursday)

T.b.a.

Journal Club Mykola Dedushenko (SUNY, Stony Brook)

at:
15:45 Other
room Zoom, instructions in abstract
abstract:

T.b.a. ------------------- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

26.10.2021 (Tuesday)

In Conversation with Sir Roger Penrose

Colloquium Roger Penrose (Oxford)

at:
19:00 Other
room Faraday Theatre, Royal Institution
abstract:

In conversation: Sir Roger Penrose, Thomas Fink & Yang-Hui He Live at the Royal Institution + Livestream Sir Roger Penrose is a mathematical physicist with the eye of an artist and the soul of a philosopher. He won the 2020 Nobel Prize in Physics for his work on the mathematical foundations of black holes. The tilings which bear his name can cover the plane in a never-repeating pattern. His work on the theory of mind suggests consciousness is a peculiarly human capability. He is a master word-smither, capable of rendering the most complex ideas clear, and his popular books have inspired a generation of physicists and laymen alike. In this event, Sir Roger joins Thomas Fink and Yang-Hui He on stage for a conversation about the man behind the science. We take a rare look into the workings of this singular mind. How does he get his ideas? Is beauty a guide to truth? What’s the basis of free will? Is AI a threat? Can art inform science? And is man different from machine? https://www.rigb.org/whats-on/events-2021/october/public-in-conversation-with-sir-roger-penrose https://lims.ac.uk/event/in-conversation-with-sir-roger-penrose/

25.10.2021 (Monday)

Lonti: (Holographic) Fermi Surfaces

Regular Seminar David Vegh (QMUL)

at:
10:30 Other
room Youtube
abstract:

Lonti Autumn 2021 Series: Lecture 2. Release of Recorded Lecture. Abstract: In this lecture, we present a few elementary facts about Fermi surfaces, then discuss how to find interesting "non-Fermi liquids" via the AdS/CFT correspondence. We study different backgrounds (e.g. AdS, BTZ, and Reissner-Nordstrom), and the wave-equation of probe fields on top of these geometries. We discuss how to compute boundary two-point functions by solving the bulk equations and then explore the results.

21.10.2021 (Thursday)

Matrix bootstrap revisited

Journal Club Zechuan Zheng (ENS Paris)

at:
15:45 Other
room Zoom, instructions in abstract
abstract:

Matrix bootstrap is a new method for the numerical study of (multi)-matrix models in the planar limit, using loop equations for moments of distribution (Ward identities and factorization of traces at infinite N). The lack of information associated with the use of only a finite number of lower moments is supplemented by the conditions of positivity of the correlation matrix. The numerical solution of loop equations and these conditions leads to inequalities for the lowest moments, which rapidly converge to exact values with an increase in the number of used moments. In our work https://arxiv.org/pdf/2108.04830.pdf, the method was tested on the example of the standard one-matrix model, as well as on the case of an ''unsolvable'' 2-matrix model with the interaction tr[A, B]^2 and with quartic potentials. We propose a significant improvement of original H. Lin's proposal for matrix bootstrap by introducing the relaxation procedure: we replace the non-convex, non-linear loop equations by convex inequalities. The results look quite convincing and matrix bootstrap seems to be an interesting alternative to the Monte Carlo method. For example, for < tr A^2 >, the precision reaches 6 digits (with modest computer resources). I will discuss the prospects for applying the method in other, physically interesting systems. --------------------- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

14.10.2021 (Thursday)

Dynamical spin chains in 4D N = 2 SCFTs

Journal Club Elli Pomoni (DESY)

at:
15:45 Other
room Zoom, instructions in abstract
abstract:

In this talk we will revisit the study of spin chains capturing the spectral problem of 4d N = 2 SCFTs in the planar limit. At one loop and in the quantum plane limit, we will discover a quasi-Hopf symmetry algebra, defined by the R-matrix read off from the superpotential. This implies that when orbifolding the N = 4 symmetry algebra down to the N = 2 one and then marginaly deforming, the broken generators are not lost, but get upgraded to quantum generators. We will also demonstrate that these chains are dynamical, in the sense that their Hamiltonian depends on a parameter which is dynamically determined along the chain. At one loop we will show how to map the holomorphic SU(3) scalar sector to a dynamical 15-vertex model, which corresponds to an RSOS model, whose adjacency graph can be read off from the gauge theory quiver/brane tiling. One scalar SU(2) sub-sector is described by an alternating nearest-neighbour Hamiltonian, while another choice of SU(2) sub-sector leads to a dynamical dilute Temperley-Lieb model. These sectors have a common vacuum state, around which the magnon dispersion relations are naturally uniformised by elliptic functions. For the example of the ℤ_{2} quiver theory we study these dynamical chains by solving the one- and two-magnon problems with the coordinate Bethe ansatz approach. --- Part of the London Integrability Journal Club. If you are a new participant, please register at integrability-london.weebly.com. The link will be emailed on Tuesday.

07.10.2021 (Thursday)

Renormalization Group Flows on Line Defects

Journal Club Zohar Komargodski (Simons Center)

at:
15:45 Other
room Zoom, instructions in abstract
abstract:

We will review the subject of line defects in d-dimensional Conformal Field Theories (CFTs). We discuss an exact formula governing the renormalization group flow on line defects and consider some examples involving line defects in 2,3, and 4 space-time dimensions. ---------------- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

17.06.2021 (Thursday)

Integrability Gong Show

Journal Club various speakers ()

at:
14:45 Other
room Zoom, instructions in abstract
abstract:

This is the last appointment before September for the London Integrability Journal Club. We will have four 10+5 mins talks by: - Ilija Buric (DESY), "Defect conformal blocks from the Iwasawa decomposition" - Luigi Guerrini (U. of Parma), "A duality for the latitude Wilson loop in ABJM", -Daniele Gregori (U. of Bologna), "Integrability and cycles of deformed N=2 gauge theory" - Enrico Olivucci (Perimeter), "Hexagons in Fishnet theories: direct derivation". Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

10.06.2021 (Thursday)

Dually weighted graphs and 2d quantum gravity

Regular Seminar Vladimir Kazakov (ENS Paris)

at:
15:15 Other
room Zoom, instructions in abstract
abstract:

Dually weighted graphs (DWG) are planar Feynman graphs bearing two sets of couplings: one set of usual couplings $t_n$ attached to the vertices of valence $n$, and another set of dual couplings $t_n^*$ attached to the faces (dual vertices) of valence $n$. Such couplings allow a deep control on possible shapes of planar graphs. For example, if one turns on only the couplings $t_4$ and $t_4^*$ the graph takes a ''fishnet form'' of a regular square lattice. The problem of counting of such graphs can be formulated as a modified hermitian one matrix model with an extra constant matrix. The partition function can be then represented in terms of the ''character expansion'' over Young tableaux, solvable by the saddle point approximation. I will review old results on DWG from my papers with M.Staudacher and Th.Wynter, including the techniques of computing Schur characters of a large Young tableau and deriving the elliptic algebraic curve for counting of planar quadrangulations. Then I will present new results from our ongoing work with F.Levkovich-Maslyuk where we count the disc quadrangulations with large, macroscopic area and boundary. This allows to extract interesting continuous limit of fluctuating 2d geometry, interpolating between the ''almost'' flat disc with a few dynamical conical defects and the disc partition function for pure 2d quantum gravity, generalizing old results for the spherical topology. ---- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

03.06.2021 (Thursday)

A gravity interpretation for the Bethe ansatz expansion of the N=4 SYM superconformal index

Journal Club Ofer Aharony (Weizmann Institute)

at:
15:15 Other
room Zoom, instructions in abstract
abstract:

This (blackboard) talk is based on 2104.13932 and on work in progress with Francesco Benini, Ohad Mamroud and Paolo Milan. I will begin by briefly reviewing the superconformal index of the d=4 N=4 SU(N) supersymmetric Yang-Mills theory, how it is related (in the large N limit) to counting black hole microstates, and how it can be computed. I will then review a specific way to compute the index called the Bethe ansatz expansion, and describe the known solutions to the Bethe ansatz equations, and what they contribute to the index in the large N limit, including both perturbative and non-perturbative terms in 1/N. The index is related to the partition function of N=4 SYM on S^3xS^1, and in the large N limit this should be related by the AdS/CFT correspondence to a sum over Euclidean gravity solutions with appropriate asymptotic behavior. I will show that each known Bethe ansatz contribution arises from a specific supersymmetric (complex) black hole solution, which reproduces both its perturbative and its non-perturbative behavior (the latter comes from wrapped Euclidean D3-branes). A priori there are many more gravitational solutions than Bethe ansatz contributions, but we show that by considering the non-perturbative effects, the extra solutions are ruled out, leading to a precise match between the solutions on both sides.---- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

20.05.2021 (Thursday)

Integrated four-point correlators in N=4 super Yang-Mills.

Journal Club Congkao Wen (QMUL)

at:
15:15 Other
room Zoom, instructions in abstract
abstract:

We will study the correlation function of four superconformal primaries in N=4 super Yang-Mills (SYM) with SU(N) gauge group. Recently, very powerful methods have been developed to compute this correlator at finite coupling based on a new concept of integrated correlators, which are defined by integrating the correlator over spacetime coordinates with suitable integration measures. The integrated correlators can be computed using supersymmetric localisation. We will mostly focus on one of the integrated correlators. An exact expression was found for this integrated correlator for arbitrary values of coupling and N. The integrated correlator can be expressed as a two-dimensional lattice sum, which manifests the SL(2, Z) modular invariance of N=4 SYM. Furthermore, the result obeys an elegant Laplace-difference equation that relates the correlator of SU(N) theory with those of SU(N-1) and SU(N+1) theories. In perturbation, the formula is checked to be consistent with known results from more standard methods. Finally, one can reconstruct the unintegrated correlator with finite coupling for first few orders in large-N expansion, the results are shown to agree with known type IIB superstring amplitudes due to AdS/CFT duality. This talk will be mainly based on arxiv.org/abs/2102.09537 (a short version can be found at arxiv.org/abs/2102.08305). --- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

13.05.2021 (Thursday)

OPE coefficients in ABJM theory with giants

Journal Club Yunfeng Jiang (CERN)

at:
15:15 Other
room Zoom, instructions in abstract
abstract:

In this talk, I will discuss a family of three-point functions in ABJM theory, both at weak and strong coupling. This family of three-point functions involve two BPS sub-determinant operators called giant gravitons and one single trace operator, which can be BPS or non-BPS. In the first part of the talk, I will explain how to compute this type of three-point function at weak coupling using a large N effective field theory. The structure constant is given by the overlap of an integrable matrix product state and a Bethe state. In the second part, I will first clarify the prescription of computation at strong coupling. I will show that it is important to perform an average over the moduli space and also take into account the contributions from wave functions. The prescription is tested in N=4 SYM theory and then applied to ABJM theory.--------- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.

06.05.2021 (Thursday)

Current operators in integrable models (a review)

Journal Club Balazs Pozsgay (Eotvos University Budapest)

at:
15:15 Other
room Zoom, instructions in abstract
abstract:

Current operators describe the flow of the conserved charges in integrable models. Whereas lots of information was known about the charges, surprisingly the current operators remained unexplored for a very long time. I review recent results in this topic, which include an exact finite volume formula for the mean values of the current operators, their embedding into the Quantum Inverse Scattering Approach (Algebraic Bethe Ansatz), and connections with long range deformations and TTbar deformations. --- Part of the London Integrability Journal Club. If you are a new participant, please register at integrability-london.weebly.com. The link will be emailed on Tuesday.

29.04.2021 (Thursday)

Scattering Amplitudes Near the Origins: Localization and Globalization

Journal Club Benjamin Basso (ENS Paris)

at:
15:15 Other
room Zoom, instructions in abstract
abstract:

I will talk about the behaviour of gluon scattering amplitudes in planar N=4 SYM near kinematical corners coined Origins where maximally-helicity-violating amplitudes are expected to be exactly Gaussian in the logs of the cross ratios and exactly predictable. In part 1, I will recall how much is known about this behaviour for the 6-gluon amplitude and interpret the result as a sort of quantum area convoluting the minimal surface TBA data with an effective coupling constant, known as the tilted cusp anomalous dimension. In part 2, I will present a generalization to any number of gluons and explore (some bit of) the emerging parterre of Origins. If time permits, I will discuss applications to scattering amplitudes in the null limit where all two-particle Mandelstam vanish simultaneously. The talk is based on a work in progress with Lance Dixon, Yu-Ting Liu and Georgios Papathanasiou. ---- Part of the London Integrability Journal Club. If you are a new participant please register at integrability-london.weebly.com. The link will be emailed.