次回のセミナー (Next Seminar)
| When: | 2024/05/15 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Kenta Suzuki (Rikkyo University) |
| Abstract: | |
| Reference: | arXiv:2403.07325 |
最近のセミナー (Recent Seminars)
| When: | 2024/06/14 (Fri.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) H2-39 |
| Speaker: | () |
| Abstract: | |
| Reference: |
| When: | 2024/06/05 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) H227B |
| Speaker: | Tomonori Ugajin (Rikkyo University) |
| Abstract: | |
| Reference: | arxiv:2403.17483 |
| When: | 2024/05/31 (Fri.) 12:30-13:30 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Yu-ki Suzuki (University of Tokyo) |
| Abstract: | |
| Reference: | arXiv:2312.07891 |
| When: | 2024/05/15 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Kenta Suzuki (Rikkyo University) |
| Abstract: | |
| Reference: | arXiv:2403.07325 |
Supersymmetric CFTs from quantum stabilizer codes
| When: | 2024/01/10 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Kohki Kawabata (University of Tokyo) |
| Abstract: | We construct fermionic conformal field theories (CFTs) whose spectra are characterized by quantum stabilizer codes. We exploit our construction to search for fermionic CFTs with supersymmetry by focusing on quantum stabilizer codes of the Calderbank-Shor-Steane type, and derive simple criteria for the theories to be supersymmetric. We provide several examples of fermionic CFTs that meet the criteria, and find quantum codes that realize N=4 supersymmetry. Our work constitutes a new application of quantum codes and paves the way for the methodical search for supersymmetric CFTs. |
| Reference: | arXiv:2307.14602 |
Excitations of bubbling geometries for line defects
| When: | 2023/12/27 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Tadashi Okazaki (Southeast U, Nanjing) |
| Abstract: | The Wilson lines in large representations of maximal supersymmetric Yang-Mills theory have the gravity dual as fully back-reacted bubbling geometries. So far little is known about the spectra of fluctuations on the bubbling geometries. From the gauge theory side we find analytic closed-form expressions of the generating functions for the spectra by studying supersymmetric indices decorated by the Wilson lines. We discover that the spectra for the bubbling geometries have intriguing counterparts in enumerative combinatorics. |
| Reference: |
Logarithmic correction to black hole entropy in universal low-energy string theory models
| When: | 2023/12/01 (Fri.) 13:30-14:30 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Gurmeet Singh Punia (Indian Institute of Science Education & Research Bhopal) |
| Abstract: | I'll discuss the computation of the logarithmic correction to the entropy of asymptotically flat and AdS black holes (rotating, non-rotating, charged, and uncharged) embedded in Einstein-Maxwell-dilaton (EMD) theories with U(1)-charged. The leading quantum gravitational corrections in both extremal and non-extremal limits of black hole temperature can be designing a standard Euclidean gravity setup that evaluates the "logarithmic term" from one-loop effective actions via heat kernel method-based calculations. EMD theories are universal building blocks of compactified string theory or supergravity models in 4D. For a concrete example, we generalize the entire setup and calculate logarithmic corrections for black holes in U(1)^2-charged EMD models intersecting with N = 4 ungauged and gauged bosonic supergravity(STU Supergravity). In contrast to flat backgrounds, all the AdS44 results are non-topological, which provides a wider "infrared window" into the microscopic degrees of freedom of black holes in string theory. |
| Reference: | arXiv:2210.16230 |
Photon sphere and quasinormal modes in AdS/CFT
| When: | 2023/11/24 (Fri.) 13:30-14:30 |
|---|---|
| Where: | Zoom online |
| Speaker: | Kakeru Sugiura (Kyoto University) |
| Abstract: | Photon spheres are the characteristic of general black holes, thus are a suitable touchstone for the emergence of gravitational spacetime in the AdS/CFT correspondence. We provide a spectral analysis of an AdS Schwarzschild black hole near its photon sphere. We find that quasinormal modes near the photon sphere reflect the AdS boundary, resulting in a peculiar spectral pattern. Our large angular momentum analysis owes to an analogue to solvable Schrödinger equations such as an inverted harmonic oscillator and the Pöschl-Teller model, with a Dirichlet boundary condition. Through the AdS/CFT dictionary, it predicts the existence of a peculiar subsector in the large angular momentum spectrum of thermal holographic CFTs on a sphere. |
| Reference: | arXiv:2307.00237 |
Complex saddles of Chern-Simons gravity and dS_3/CFT_2 correspondence
| When: | 2023/07/19 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Yasuaki Hikida (YITP) |
| Abstract: | It would be useful to deal with complex geometry when examining quantum gravity as in the case of no-boundary proposal by Hartle and Hawking. However, there would be too many saddles for complexified gravity, and it is necessary to determine which are allowable geometries in the sense of Witten. As a simple example, we examine three-dimensional gravity theory with positive cosmological constant described by Chern-Simons gauge theory. Applying dS_3/CFT_2 correspondence we recently proposed, we determine the set of allowable complex saddles for the Chern-Simons gravity from its dual conformal field theory. |
| Reference: | arXiv:2306.03330 |
4d N=2* Schur indices and line operators
| When: | 2023/07/14 (Fri.) 13:00-14:00 |
|---|---|
| Where: | Zoom online |
| Speaker: | Tadashi Okazaki (Southeast U., Nanjing) |
| Abstract: | We study the exact closed-form expressions for the Schur indices and correlation functions of line operators of 4d N=4 and N=2* U(N) super Yang-Mills theory in the canonical and grand canonical ensembles via the Fermi-gas method. They are expressible in terms of the (twisted) Weierstrass functions and the (generalized) Kronecker theta series. We also discuss the holographic dual and combinatorial aspects of these observables. The talk will be based on https://arxiv.org/abs/2208.01426 and https://arxiv.org/abs/2303.14887. |
| Reference: | arXiv:2303.14887, arXiv:2208.01426 |
Topological recursion and its refinement and generalisations
| When: | 2023/06/30 (Fri.) 13:00-14:00 |
|---|---|
| Where: | 227B Honkan (Main Bldg.) |
| Speaker: | Kento Osuga (Tokyo U.) |
| Abstract: | Topological recursion is a powerful mathematical formalism that appears in enumerative geometry, algebraic geometry, and mathematical/theoretical physics. The list of applications includes Gromov-Witten invariants, matrix model correlators, and more. In this talk, I will first give a brief review of what topological recursion is, and show a relation to the Virasoro algebra. Then, I will define the hyperelliptic refined topological recursion and discuss a conjectural relation to Nekrasov partition functions. If time permits, I will mention other possible generalisations, e.g. the N=1 supersymmetric topological recursion. |
| Reference: | arXiv:2305.02494 |
| When: | 2023/06/21 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 227B |
| Speaker: | Kilar Zhang (U. Shanghai) |
| Abstract: | AGT conjecture reveals a connection between 4D $\mathcal{N}=2$ gauge theory and 2D conformal field theory. Though some special instances have been proven, others remain elusive and the attempts on its full proof never stop. When the $\Omega$ background parameters satisfy $-\epsilon_1/\epsilon_2\equiv \beta =1$, the story simplifies a bit. A proof of the correspondence in the case of $A_{1}$ gauge group was given in 2010 by Mironov et al., while the $A_{n}$ extension is verified by Matsuo and Zhang in 2011, with an assumption on the Selberg integral of $n+1$ Schur polynomials. Then in 2020, Albion et al. obtained the rigorous result of this formula. In this paper, we show that the conjecture on the Selberg integral of Schur polynomials is formally equivalent to their result, after applying a more complicated complex contour, thus leading to the proof of the $A_{n}$ case at $\beta=1$. To perform a double check, we also directly start from this formula, and manage to show the identification between the two sides of AGT correspondence. |
| Reference: | arXiv:2305.11839 |
Wave Packets in AdS/CFT Correspondence
| When: | 2023/06/07 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Zoom online |
| Speaker: | Seiji Terashima (YITP) |
| Abstract: | We construct a general bulk wave packet in the AdS/CFT correspondence. This wave packet can be described both in bulk and CFT descriptions. Then, we compute the time evolution of the energy density of this wave packet state on the vacuum in the CFT picture of $AdS_3/CFT_2$. We find that the energy density of the wave packet is localized in two points, which means that the bulk wave packet corresponds to two light-like particle-like objects in the CFT picture. Our result implies that the entanglement wedge reconstruction is invalid. The fact that it is wrong is related to the fact that the bulk gravity theory, which is the low energy effective theory of the CFT, can be invalid if we consider a subregion of spacetime and the violation of the equivalence principle in AdS/CFT. |
| Reference: | arXiv:2304.08478 |
Quantization and Integrability in Supergroup Theory
| When: | 2023/05/31 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Zoom online |
| Speaker: | Taro Kimura (Institut de Math´ematiques de Bourgogne) |
| Abstract: | Geometry serves as a unifying language in the study of integrable systems, providing insights into the underlying structures. Moreover, its quantization problem is still a challenging issue involving various aspects in Physics and Mathematics. In this talk, I’d like to discuss this issue for systems associated with supergroup structure, supermatrix model and supergroup gauge theory, which show various similarities in the relation to geometry. In particular, I’ll discuss their spectral curves and quantization problem, and also the Bethe/Gauge correspondence for supergroup gauge theory. This talk is based on a review article, https://arxiv.org/abs/2301.05927 |
| Reference: | arXiv:2301.05927 |
S1 Reduction of 4D N=3 SCFTs and Squashing Independence of ABJM Theories
| When: | 2023/05/26 (Fri.) 12:30-13:30 |
|---|---|
| Where: | Zoom online |
| Speaker: | Tomoki Nakanishi (Osaka Metropolitan University) |
| Abstract: | We study the compactification of 4D $\mathcal{N} = 3$ superconformal field theories (SCFTs) on $S^1$, focusing on the relation between the 4D superconformal index and 3D partition function on the squashed sphere $S^3_b$. Since the center $\mathfrak{u}(1)$ of the $\mathfrak{u}(3)$ R-symmetry of the 4D theory can mix with an $\mathcal{N}=6$ abelian flavor symmetry in three dimensions, the precise 4D/3D relation for the global symmetry is not obvious. Focusing on the case in which the 3D theory is the ABJM theory we demonstrate that the above R-symmetry mixing can be precisely identified by considering the Schur limit (and/or its $\mathcal{N}=3$ cousin) of the 4D index. As a result, we generalize to the ABJM theories recent discussions on the connection between supersymmetry enhancement of the 4D index and squashing independence of the $S^3_b$ partition function. |
| Reference: | arXiv:2211.07421 |
Exact WKB analysis of certain linear third-order differential equations with a large parameter
| When: | 2023/04/19 (Wed.) 16:00-18:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 254 |
| Speaker: | Gergő Nemes (Tokyo Metropolitan Univ.) |
| Abstract: | A class of linear third-order differential equations with a large parameter $u$ is considered. A special case of such equations has been recently studied by Ito, Kondo and Shu in connection with the wall-crossing of the TBA equations. Analytic solutions of this type of equations can be described via (divergent) formal series in descending powers of $u$. We call these formal series solutions the WKB solutions. We show that under mild conditions on the potential function of the equation, the WKB solutions are Borel summable with respect to the parameter $u$ in large, unbounded domains of the independent variable. It is established that the formal series expansions are the asymptotic expansions, uniform with respect to the independent variable, of the Borel re-summed solutions. In addition, it is proved that the WKB solutions can be expressed using factorial series in the parameter, and that these expansions converge in half-planes, uniformly with respect to the independent variable. We illustrate our theory by application to a third-order Airy-type equation, which we shall also solve using integral methods. Generalisations, possible extensions to turning point problems and some further research problems will also be discussed. |
| Reference: |
The Tensionless Limit of Pure-Ramond-Ramond AdS3/CFT2
| When: | 2023/03/22 (Wed.) 17:30-18:30 |
|---|---|
| Where: | Honkan (Main Bldg.) 254 seminar room |
| Speaker: | Ryo Suzuki (Shing-Tung Yau Center of Southeast University) |
| Abstract: | Despite impressive advances in the AdS3/CFT2 correspondence, the setup involving Ramond-Ramond backgrounds, which is related to the D1-D5 system of branes, remained not well-understood. We use the mirror TBA equations to study the spectrum of pure Ramond-Ramond AdS3× S3× T4 strings. We find that the leading-order contribution to the anomalous dimensions at small tension contain massless worldsheet excitations, i.e. the T4 bosons and their superpartners. |
| Reference: | https://arxiv.org/abs/2303.02120 |
Anomaly Inflow of Rarita-Schwinger Field in 3 Dimensions
| When: | 2023/03/01 (Wed.) 11:30-12:30 |
|---|---|
| Where: | zoom on line |
| Speaker: | Saki Koizumi (DIAS) |
| Abstract: | We study the anomaly inflow of the Rarita-Schwinger field with gauge symmetry in 3 dimensions. We find that global anomalies of the Rarita-Schwinger field are obtained by the spectral flow, which is similar to Witten’s SU(2) global anomaly for a Weyl fermion. The Rarita-Schwinger operator is shown to be a self-adjoint Fredholm operator, and its spectral flow is determined by a path on the set of self-adjoint Fredholm operators with the gap topology. From the spectral equivalence of the spectral flow, we find that the spectral flow of the Rarita-Schwinger operator is equivalent to that of the spin-3/2 Dirac operator. From this fact, we confirm that the anomaly of the 3-dimensional Rarita-Schwinger field is captured by the anomaly inflow. Finally, we find that there are no global anomalies of gauge-diffeomorphism transformations on spin manifolds with any gauge group. We also confirm that the anomalous phase of the partition function which corresponds to the generator of ΩPin+ (pt) = Z is exp(3iπ/8) for the Rarita-Schwinger theory on unorientable Pin+ 4 16 manifolds without gauge symmetry. |
| Reference: | arXiv:2302.00597 |
Effective field theory in light of relative entropy
| When: | 2023/01/18 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) H254 |
| Speaker: | Naoto Kan (Osaka Univ.) |
| Abstract: | We study constraints on the effective field theory (EFT) from the relative entropy between two theories: we refer to these as target and reference theories. The consequence of the non-negativity of the relative entropy is investigated by choosing some reference theories for a given target theory involving field theories, quantum mechanical models, etc. It is found that the constraints on EFTs, e.g., the single massless scalar field with the dimension-eight operator, and SMEFT dimension-eight SU(N) gauge bosonic operators, are consistent with the positivity bounds from the unitarity and causality when the higher-derivative operators are generated by the interaction between heavy and light fields. The constraints on Einstein-Maxwell theory with higher-derivative operators from the non-negativity of relative entropy are also investigated. The constraints on such EFTs from the relative entropy hold under an assumption that perturbative corrections from the interaction involving higher-derivative operators of light fields are not dominant in the EFTs. The consequence of this study on the weak gravity conjecture and the second law of thermodynamics is also discussed. |
| Reference: | arXiv:2211.08065 |
Complex saddle points and resurgence structure of nonlinear Schrödinger system
| When: | 2022/12/21 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Honkan (Main Bldg.) 254 |
| Speaker: | Toshiaki Fujimori (Keio University) |
| Abstract: | Resurgence theory is a theory that relates perturbative series to non-perturbative effects and is considered necessary for understanding field theories in a non-perturbative manner. Recently, the resurgence structure of some integrable field theories has been investigated by exploiting their integrability. It has been shown that there exist new ``renormalon" type ambiguities in the perturbation series of some integrable field theories. Although non-renormalon type ambiguities are expected to be cancelled by non-perturbative contributions of complex saddle points of the action, whether the new ``renormalon" type ambiguities are related to complex saddle points is still an open question. We discuss the relationship between the complex saddle points and the resurgence structure in the two-dimensional nonlinear Schrödinger system from the viewpoint of the Lefschetz-thimble method. Using the inverse scattering method, we find a candidate complex saddle point that would cancel the new renormalon type ambiguity. |
| Reference: | arXiv:2205.07436 |
The holography of duality in $\mathcal{N} = 4$ Super-Yang-Mills-theory
| When: | 2022/11/09 (Wed.) 16:00-17:00 |
|---|---|
| Where: | Zoom online |
| Speaker: | Shinji Hirano (Huzhou Univ.) |
| Abstract: | Via the AdS/CFT correspondence, I discuss the gravity dual description of a class of $\mathcal{N} = 4$ Super-Yang-Mills theories with $su$, $so$ and $sp$ gauge algebras, differing by the global 1-form symmetries and its associated line operator spectrum. These fine prints are encoded in the boundary conditions on the NSNS and RR 2-forms in type IIB string theory on $AdS_5 \times S^5$ and $AdS_5 \times \mathbb{R}P^5$ and described by simple 5d topological field theories. The holographic description provides an elementary and intuitive understanding of the rich properties of these theories such as an intricate web of the $SL(2,Z)$ duality, mixed ’t Hooft anomalies, interfaces as well as the existence of more $\mathcal{N} = 4$ Super-Yang-Mills theories. Time permitting, I make brief comments on non-invertible (higher category) symmetries and add a speculative discussion on an ensemble of $\mathcal{N} = 4$ SYM theories. |
| Reference: | arXiv:2208.09396 |