理论物理研讨会
We organize theoretical physics seminars regularly. The seminars are broadcasted online mostly by Zoom (sometimes in other methods). Interested people are free to join without registration in advance.
The Zoom info is
URL: https://us02web.zoom.us/j/3854420225?pwd=SXY4eWJKOTBFZWJDaE16aXpTamY1QT09
Meeting ID: 385 442 0225
Passcode: yauc
and China Standard Time (UTC+8) is used.
If you wish to give a talk, please write to any one of the faculty members. For other workshops, contact the organizers for the details.
Seminar information can also be found on the website of our Theoretical Physics Group at YCSEU. Events (yaucseu.github.io)
Past Seminars and Workshops
| Date | Name | Title |
Jan 7 (Fri), 2022 14:00-15:30 | Stavros Garoufalidis (SUSTech) | From knots to q-series, a tale of discoveries |
Abstract | ||
Jan 5 (Wed), 2022 14:00-15:30 | Gang Yang (ITP-CAS) | Color-kinematics duality and double-copy of form factors |
Abstract Recent studies of scattering amplitudes reveal an intrigue duality between color and kinematics. This color-kinematics (CK) duality also indicates a deep connection between gauge and gravity theories via the so-called double copy. In this talk, I will first give an introduction to the CK duality and the double-copy picture, then I will discuss some new progress on the high-loop CK-dual solutions and the double-copy prescription for form factors. | ||
Dec 28 (Tue), 2021 14:00-15:00 | Ling-yan Hung (Fudan) | Some lessons learned from the p-adic tree and efforts towards a holographic tensor networks for real 1+1 dimensional CFTs |
| Abstract We will discuss what the p-adic tensor network may have taught us about RG fixed point and how those ideas can be generalized to 1+1 dimensional CFTs and beyond, making use of the connection between CFTs and topological theories in one higher dimensions. | ||
Dec 8 (Wed), 2021 15:00-16:00 | Wei Song (YMSC Tsinghua) | A BMS-invariant free scalar model(Slides) |
| Abstract The BMS (Bondi-van der Burg-Metzner-Sachs) symmetry arises as the asymptotic symmetry of flat spacetime at null infinity, suggesting a holographic duality between Einstein gravity and some quantum field theory with BMS invariance. In particular, the BMS algebra in three dimensions is generated by super-rotation generators which form a Virasoro sub-algebra, together with mutually-commuting super-translation generators. In this talk, I will first review flat holography in three dimensions, and then describe a free scalar model in two dimensions exhibiting BMS symmetry. | ||
Dec 7 (Tue), 2021 10:00-11:00 | Hernán González (Adolfo Ibanez) | The structure of IR divergences in celestial gluon amplitudes(slides) |
| Abstract Celestial amplitudes reveal two-dimensional conformal properties of scattering amplitudes for massless particles. In this talk we describe the factorization properties of infrared regulated gluon amplitudes in terms of celestial data. We show that the full divergent contribution becomes a scalar correlator of the product of celestial primaries. The effect of these operators on the hard amplitude is a shift in the scaling dimensions of each asymptotic state by an infinite amount, proportional to the cusp anomalous dimension. We finalize this talk by commenting on the properties of the celestial CFT controlling infrared and non-abelian degrees of freedom. | ||
Nov 16 (Tue), 2021 16:00-17:00 | Fabio Apruzzi (AEC Bern) | 2-groups in 5d and 6d theories(slides) |
| Abstract I will discuss 2-group symmetries in 5d and 6d theories, with a particular focus on superconformal field theories (SCFTs). These symmetries arise when the discrete 1-form symmetry and continuous flavor symmetry group of a theory mix with each other under group multiplication. I will first introduce some general aspects about 2-groups. I will then describe how the 2-group symmetry appears in a specific locus of the extended Coulomb branch of the 5d N=1 SU(2) theory at 0 theta angle. More examples of 2-groups in 5d will be provided, where a notion of perturbative and non-perturbative 2-group can be introduced. Finally, I will discuss the classification of 6d theories with 2-group symmetries. | ||
Nov 9 (Tue), 2021 9:00-10:00 | John Cardy (Berkeley) | A Physical Interpretation of the TTbar Deformation of 2d Field Theory (slides, video) |
| Abstract I will argue that the TTbar deformation of a field theory may be understood as a coupling to an elastic medium, with, however, unusual properties. In the fixed stress ensemble the evolution equations are then much simpler compared to the usual fixed geometry, and are explicitly modular invariant. In fact they are those of a simple fluid, for which, however, the singular initial conditions of conformal field theory may lead to the formation either of shock waves, or collapse, giving rise to the observed singular behavior of the partition function in fixed geometry. | ||
Nov 2 (Tue), 2021 17:00-18:00 | Pietro Longhi (ETH) | Quivers, affine symmetries and wall-crossing invariance (slides) |
| Abstract The spectrum of BPS states of M theory on local del Pezzo and Hirzebruch surfaces encodes rank-zero DT invariants for the associated derived category of coherent sheaves. Combining wall-crossing invariance with affine Lie symmetries realized as automorphisms of the BPS quiver, we derive exact constraints on the BPS monodromy of Kontsevich-Soibelman. Solving these equations leads to conjectural expressions for the BPS monodromy, encoding the whole BPS/DT spectrum in any chamber of the moduli space of stability conditions. Based on joint work with Fabrizio del Monte. | ||
Nov 1 (Mon), 2021 16:00-17:00 | Shouvik Datta (CERN) | Operator growth in 2d CFTs (slides) |
| Abstract Simple, local operators irreversibly grow into ones with higher complexity at late times in quantum chaotic systems. In this talk, I shall discuss this dynamics of operator growth in irrational 2d CFTs. First, I shall review a recent paradigm, based on the Lanczos algorithm, to analyze operator growth in quantum systems. I shall then demonstrate how this algorithm can be suitably modified for 2d CFTs and how to extract quantitative features regarding growth of simple operators (primaries and the stress tensor). Under a specific evolution protocol, growth of primary operators proceeds as a flow into the 'bath of descendants' of its Verma module. These descendants are labeled by integer partitions and have a one-to-one map to Young diagrams. This correspondence leads to a concrete visualization of operator growth as paths spreading along the Young's lattice. (Based on arXiv:2110.10519 with Pawel Caputa) | ||
Oct 19 (Tue), 2021 16:00-17:00 | Cyril Closset (Birmingham) | The U-plane of rank-one 4d N=2 KK theories（slides） |
| Abstract I will revisit the Seiberg-Witten description of the Coulomb branch of rank-one 4d N=2 supersymmetric QFTs, including aspects of the global symmetry, from the point of view of rational elliptic surfaces. This will include, in particular, a detailed study of the 5d superconformal field theories with E_n symmetry, compactified on a circle. I will also sketch how to derive BPS quivers from that perspective. Interesting modular properties of the SW geometries will play a key role. | ||
Oct 12 (Tue), 2021 16:00-17:00 | Zoltan Bajnok (Wigner Insitute) | From perturbative to non-perturbative in the O(4) sigma model（slides） |
| Abstract Is it possible to derive non-perturbative contributions in a quantum field theory knowing only the perturbative coefficients? We answer this question affirmatively based on the careful analysis of the integrable two dimensional O(4) sigma model. We investigate its ground state energy in a magnetic field, for which integrability provides an exact linear integral equation. By cleverly expanding this equation we could calculate a large number of very precise, factorially growing perturbative coefficients. By investigating their asymptotical behaviour on the Borel plane we managed to reveal a nice resurgence structure leading to the first few exponentially suppressed non-perturbative terms of the ambiguity free trans-series. We checked our results against the direct numerical solution of the exact integral equation and find complete agreement. (based on 2011.12254 and 2011.09897) | ||
Sep 14 (Tue), 2021 16:00-17:00 | Marcos Marino (Geneva) | Resurgence and renormalons in quantum field theory (slides) |
Abstract | ||
| Jul 9 - Aug 6, 2021 | Southeast Summer Seminar Series | |
| Feb 5 - 19, 2021 | Southeast Winter Seminar Series | |