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次回のセミナー (Next Seminar)

Sphere correlation functions and Verma modules

When:2020/03/30 (Mon.) 13:30-14:30
Where:Honkan (Main Bldg.) H2-84A
Speaker:Okazaki Tadashi (Perimeter Institute)
Abstract:We propose a universal IR formula for the three-sphere partition function and protected correlation functions of Higgs and Coulomb branch operators of 3d N=4 supersymmetric quantum field theories with massive, topologically trivial vacua. The talk will be based on my recent work arXiv:1911.11126 with Davide Gaiotto.

最近のセミナー (Recent Seminars)

Sphere correlation functions and Verma modules

When:2020/03/30 (Mon.) 13:30-14:30
Where:Honkan (Main Bldg.) H2-84A
Speaker:Okazaki Tadashi (Perimeter Institute)
Abstract:We propose a universal IR formula for the three-sphere partition function and protected correlation functions of Higgs and Coulomb branch operators of 3d N=4 supersymmetric quantum field theories with massive, topologically trivial vacua. The talk will be based on my recent work arXiv:1911.11126 with Davide Gaiotto.

Finding black holes' microstates

When:2020/02/10 (Mon.) 13:30-15:30
Where:Honkan (Main Bldg.) H2-84A
Speaker:Seyed Morteza Hosseini (Kavli IPMU)
Abstract:In the first part, I’ll review recent progresses in counting microstates of stringy black holes in AdS spacetimes. The main tools in achieving an exact counting are holography and supersymmetric localization. Combining these two I’ll explain how to derive the Bekenstein-Hawking entropy, including its numerical factor, for different classes of AdS black holes. Then, in the second part of my talk I'll explain a geometric realization of the previous counting.


When:2020/01/29 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Masako Asano (Seikei Univ.)

JT gravity, KdV equations and macroscopic loop operators

When:2020/01/22 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Kazuhiro Sakai (Meiji Gakuin Univ.)
Abstract:We study the thermal partition function of Jackiw-Teitelboim (JT) gravity in asymptotically Euclidean $AdS_2$ background using the matrix model description recently found by Saad, Shenker and Stanford [arXiv:1903.11115]. We show that the partition function of JT gravity is written as the expectation value of a macroscopic loop operator in the old matrix model of 2d gravity in the background where infinitely many couplings are turned on in a specific way. Based on this expression we develop a very efficient method of computing the partition function in the genus expansion as well as in the low temperature expansion by making use of the Korteweg-de Vries constraints obeyed by the partition function. We have computed both these expansions up to very high orders using this method. It turns out that we can take a low temperature limit with the ratio of the temperature and the genus counting parameter held fixed. We find the first few orders of the expansion of the free energy in a closed form in this scaling limit. We also study numerically the behavior of the eigenvalue density and the Baker-Akhiezer function using the results in the scaling limit.


When:2019/12/18 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Yasuyuki Hatsuda (Rikkyo Univ.)

The Geometry of SUSY Enhancement

When:2019/12/13 (Fri.) 13:00-14:00
Where:Honkan (Main Bldg.) H2-84A
Speaker:Hirotaka Hayashi (Tokai Univ.)
Abstract:We provide a precise geometric picture that demystifies the phenomenon of supersymmetry enhancement along certain RG flows of four-dimensional theories, recently discovered by Maruyoshi and Song. From UV theories we are able to derive the Seiberg-Witten geometries and all conformal dimensions of Coulomb branch operators for the infrared theories, without using a-maximization.

Entropy of the Janus interface in four-dimensional N=2 superconformal field theories

When:2019/11/13 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Lento Nagano (Tokyo Univ.)
Abstract:We construct an co-dimension 1 defect, called the Janus interface, in four-dimensional N=2 superconformal field theories across which a coupling constant changes its value.
We then define its entropy as a contribution to entanglement entropy and show that the entropy associated to the Janus interface is given by a ratio of partition functions with and without the interface.
By using this fact, we compute the entropy of the Janus interface to show that it is proportional to a particular linear combination of analytically continued Kahler potentials, as conjectured in 1805.09981 by Goto and Okuda.
This presentation is based on a work in progress with K. Goto, T. Nishioka, and T. Okuda.

Topological order in the color-flavor locked phase of (3+1)-dimensional U(N) gauge-Higgs system

When:2019/11/01 (Fri.) 13:30-14:30
Where:Honkan (Main Bldg.) H2-84A
Speaker:Ryo Yokokura (KEK)
Abstract:We study a (3+1)-dimensional U(N) gauge theory with N-flavor fundamental scalar fields, whose color-flavor locked (CFL) phase has topologically stable non-Abelian vortices. The U(1) charge of the scalar fields must be Nk+1 for some integer k in order for them to be in the representation of U(N) gauge group. This theory has a Z_{Nk+1} one-form symmetry, and it is spontaneously broken in the CFL phase, i.e., the CFL phase is topologically ordered if k is not 0. We also find that the world sheet of topologically stable vortices in CFL phase can generate this one-form symmetry.

Dirac quantization and Maxwell anomaly in string theory

When:2019/10/30 (Wed.) 16:15-17:15
Where:Honkan (Main Bldg.) H284
Speaker:Kazuya Yonekura (Tohoku University)

Linearized Field Equations of Gauge Fields from the Entanglement First Law

When:2019/10/25 (Fri.) 13:00-14:00
Where:Honkan (Main Bldg.) H2-84A
Speaker:Kenta Hasegawa (Saitama Univ.)
Abstract:In the context of the AdS/CFT correspondence linearized field equations of vector and antisymmetric tensor gauge fields around an AdS background are obtained from the entanglement first law of CFTs. The holographic charged entanglement entropy contains a term depending on the gauge field in addition to the Ryu-Takayanagi formula.

Wall-crossing and operator ordering for 't Hooft operators in N=2 gauge theories

When:2019/07/24 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Takuya Okuda (Univ. of Tokyo, Komaba)
Abstract:In this talk I will report on a joint work with H. Hayashi and Y. Yoshida on 't Hooft operators. We study half-BPS 't Hooft line operators in 4d N=2 gauge theories on S^1 x R^3 with omega-deformation. Non-perturbative contributions, namely monopole screening contributions, to the correlator of 't Hooft operators can be computed using quiver supersymmetric quantum mechanics. We show that for a gauge group U(N) there is a direct relation between a chamber in the space of FI parameters of SQM's and the ordering of 't Hooft operators. For U(N) SQCD with N_F flavors, wall-crossing occurs only when a minimal 't Hooft operator passes another minimal operator of a different kind and their ordering changes. We demonstrate this by working out several examples.


When:2019/07/17 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Toshihiro Ota (RIKEN)

Holographic Complexity in the Jackiw-Teitelboim Gravity

When:2019/07/10 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Kanato Goto (RIKEN)
Abstract:In the last few years, a deep connection between spacetime geometry and quantum information theoretic properties has been found in the context of AdS/ CFT correspondence. The most famous example is the so-called Ryu-Takayanagi formula which relates the area of the co-dimension two surface in AdS to the entanglement entropy in the CFT. Recently, a new gravity/information connection was found between the size of the interior region of black holes in AdS and the computational complexity in the CFT.
In joint work with Marrochio, Myers, Queimada, and Yoshida, we analyzed the behavior of the holographic complexity in the so-called Jackiw-Teitelboim model (JT model), which is the two-dimensional dilaton gravity theory which describes the nearly AdS2 geometry. In the Complexity=Action proposal, we showed that the late-time growth rate vanishes for the JT model. This vanishing complexity mirrors the behavior for the magnetic Reissner-Nordstrom-AdS black holes in four dimensions, which play a role in constructing the JT action via dimensional reduction. This situation can be ameliorated by instead considering a dimensional reduction describing the near-horizon physics of near-extremal electric black holes in four dimensions. We found that in the resulting two-dimensional dilaton gravity theory, which we call JT-like theory, the late time growth rate is non-vanishing and it approaches the value of the Lloyd bound.
In four dimensions, there is a boundary term involving the Maxwell field, which one can add to the gravitational action. We also considered the dimensional
reduction of the Maxwell boundary term and found that it changes the late time behavior of the complexity for both cases.

Argyres-Douglas Theories and Liouville Irregular States

When:2019/07/03 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Takahiro Uetoko (Ritsumeikan univ.)
Abstract:We study irregular states of rank-two and three in Liouville theory, based on an ansatz proposed by D. Gaiotto and J. Teschner. Using these irregular states, we evaluate asymptotic expansions of irregular conformal blocks corresponding to the partition functions of $(A_1,A_3)$ and $(A_1,D_4)$ Argyres-Douglas theories for general $\Omega$-background parameters. In the limit of vanishing Liouville charge, our result reproduces strong coupling expansions of the partition functions recently obtained via the Painleve/gauge correspondence. We also find that our partition functions are invariant under the action of the Weyl group of flavor symmetries once four and two-dimensional parameters are correctly identified. We finally propose a generalization of this parameter identification to general irregular states of integer rank.

The memory effect of Entanglement in 2D CFTs

When:2019/06/24 (Mon.) 16:00-18:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Song He (Jilin University, Professor)
Abstract:We will talk about the memory effect of entanglement entropy of locally excited states in two-dimensional conformal field theories (CFTs). In particular, we consider excited states obtained by acting on a vacuum with primary operators. We show that the entanglement entropy increases by a finite constant amount under its time evolution.
Moreover, in rational conformal field theories, we prove that this increase of the (both Renyi and von Neumann) entanglement entropy always coincides with the log of the quantum dimension of the primary operator. Further, we also show the behavior of the time evolution of Entanglement in 2D quantum gravity and WCFTs. If the time is allowed, we will talk about the recent progress on this object in various deformed field theory.

Triangle anomalies and nonrelativistic Nambu-Goldstone modes of generalized global symmetries

When:2019/06/19 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Noriyuki Sogabe (Keio university)
Abstract:In massless QCD coupled to QED in an external magnetic field, a photon with the linear polarization in the direction of the external magnetic field mixes with the charge neutral pion through the triangle anomaly, leading to one gapless mode with the quadratic dispersion relation $ω$∼$k^2$ and one gapped mode. In this talk, we show that this gapless mode can be interpreted as the so-called type-B Nambu-Goldstone (NG) mode associated with the spontaneous breaking of generalized global symmetries and that its presence is solely dictated by the anomalous commutator in the symmetry algebra. We also argue a possible realization of such nonrelativistic NG modes in $3$-dimensional Dirac semimetals.


When:2019/06/10 (Mon.) 13:30-14:30
Where:Honkan (Main Bldg.) H2-39
Speaker:Naoki Sasakura (YITP)

Deep learning & holographic QCD

When:2019/05/29 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Akinori Tanaka (Riken)
Abstract:There is no doubt about that the deep learning (DL) is the one of the recent epoch-making achievement of the science.
Recently, there are some movements in scientific community to apply DL or machine learning techniques to study their research fields.
Even particle physics and string theory are not out of that movements.
In this talk, I will review the concept of DL and our proposal to apply it to find gravity dual of given field theory.
After that, I talk on our recent application in the context of holographic QCD.
Reference:Physical Review D, 98(4), 046019.(arXiv:1802.08313)
Physical Review D, 98(10), 106014.(arXiv:1809.10536)

Super instanton counting and localization

When:2019/05/08 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Taro Kimura (Keio university)
Abstract:We study the super instanton solution in the gauge theory with $U(n_+|n_−)$ gauge group. Based on the ADHM construction generalized to the supergroup theory, we derive the instanton partition function from the super instanton moduli space through the equivariant localization. We derive the Seiberg–Witten geometry and its quantization for the supergroup gauge theory from the instanton partition function, and study the connection with classical and quantum integrable systems. We also argue the brane realization of the supergroup quiver gauge theory, and possible connection to the non-supergroup quiver gauge theories.

Anomaly, regularization and partition function on lens space

When:2019/04/24 (Wed.) 16:00-17:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Shuichi Yokoyama (YITP)
Abstract:In this talk, I will speak about how to derive a correct phase factor in partition function of N=2 SUSY gauge theory on three-manifold using three-sphere and lens space.
In particular we reproduce a holonomy dependent phase factor associated Chern-Simons term derived by Imamura-Matsuno-Yokoyama from a fermion 1-loop determinant of regularization ghost for a vector multiplet.
Our result improves their work on lens space partition function, and passes a couple of duality tests including the total phase.

Correlation Functions on the 1/2-BPS Wilson Loop: Perturbation and Integrability

When:2019/02/22 (Fri.) 13:30-15:00
Where:Honkan (Main Bldg.) H2-39
Speaker:Naoki Kiryu (Tokyo U., Komaba )
Abstract:We study correlation functions of local operators inserted on the 1/2-BPS Wilson loop in planar N = 4 supersymmetric Yang-Mills theory in four dimensions. This is consistent with a holographic description of the correlators of open strings attached to D-branes in AdS5×S5. We first conjecture the finite coupling expression of the correlators in view of the integrability-based approach called “hexagonalization”, which was introduced previously to study the correlation functions in the absence of the Wilson loop. We next perform direct perturbative computation. Through the comparison with “hexagonalization”, we refine the conjecture for the integrability-based approach to the correlators on the 1/2-BPS Wilson loop.
Reference:arXiv:1706.02989, arXiv:1710.07325, arXiv:1812.04593.