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KEK Theory workshop 2019

Dec 3 – 6, 2019
KEK
Japan timezone

Contribution List

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5. Quantum Gravity and Naturalness
Prof. Hikaru Kawai
12/3/19, 10:30 AM
We discuss the possibility that naturalness can be understood as an effect of quantum gravity. In particular, we will consider a mechanism by which the electroweak scale is naturally obtained from the Planck scale.
6. Status of asymptotic safety in gravity-matter systems
Dr Masatoshi Yamada
12/3/19, 11:30 AM
Asymptotically safe quantum gravity is one of candidates for quantum gravity. It is essential that there exists a non-trivial fixed point for gravitational couplings. In this talk we review the current status of the asymptotic safety scenario for gravity-matter systems.
7. An Approach to Quantum Gravity -- Asymptotic Safety --
Prof. Nobuyoshi Ohta
12/3/19, 1:30 PM
We explain an approach to formulate quantum gravity within the framework of local quantum field theory using functional renormalization group. called asymptotic safety. Starting how the approach is formulated, we intoduce the notion of critical surface and discuss its dimensionality. Several physical aspects of this approach are also discussed including quantum effective action derived from...
18. Gravitational Thomas Precession Effect as a New Cosmological Probe
Mr Anand Hegde
12/3/19, 2:30 PM
Thomas Precession has been extensively studied as a special relativistic effect.In this paper, we study Thomas like precession of spinning tops in the presence of gravitational fields. To establish this effect we evaluate a system whose spin is defined by a spin-four vector near a strong source of gravitational waves. It can be shown that for a system like hydrogen atom in a strong...
19. Catalytic Creation of Baby Bubble Universe with Small Positive Cosmological Constant
Prof. Yutaka Ookouchi
12/3/19, 2:45 PM
We investigate the decay of metastable de Sitter, Minkowski and anti-de Sitter vacua catalyzed by a black hole and a cloud of strings. We apply the method to the creation of the four dimensional bubble universe in the five dimensional anti-de Sitter spacetime recently proposed by Banerjee, Danielsson, Dibitetto, Giri and Schillo. We study the bounce action for the creation and find that the...
20. Evidence for Weak-Coupling Holography from the Gauge/Gravity Correspondence for Dp-branes
Prof. Yasuhiro Sekino
12/3/19, 3:00 PM
Gauge/gravity correspondence is regarded as a powerful tool for the study strongly-coupled quantum systems, but its proof is not available. An unresolved issue that should be closely related to the proof is what kind of correspondence exists, if any, when gauge theory is weakly coupled. We report progress about this limit for the case associated with D$p$-branes ($0\le p\le 4$), namely, the...
21. Supersymmetric non-abelian D-brane equations from open pure spinor superstring
Dr Sota Hanazawa
12/3/19, 3:15 PM
We have examined the BRS invariance of the open pure spinor superstring to derive equations of motion for a supersymmetric D$p$-brane, which should be induced from the DBI action and the Wess-Zumino action. These equations are consistent with the dimensional reduction of equations for a supersymmetric D9-brane obtained by Berkovits and Pershin. They also analyzed non-abelian backgrounds up to...
58. Decoding the Path Integral: Resurgence and Non-Perturbative Physics
Prof. Gerald Dunne
12/3/19, 4:30 PM
There are several important conceptual and computational questions concerning the Minkowski space path integral, which have recently been approached from a new perspective motivated by "resurgent asymptotics", which is a novel mathematical formalism that seeks to unify perturbative and non-perturbative physics. In this general talk, I will introduce the basic ideas, report on some examples in...
8. IR renormalon in a compactified spacetime: the case of the QCD(adj.) on $R^3\times S^1$
Prof. Hiroshi Suzuki
12/4/19, 9:30 AM
An interesting possibility that the ambiguity in perturbation theory caused by the IR renormalon is cancelled by the instability associated with a semi-classical object called bion has been suggested in the context of the resurgence program of asymptotically-free quantum field theories. To reinforce this picture on the IR renormalon, the understanding of the IR renormalon in a compactified...
9. Resurgence and Phase Transitions
Prof. Gerald Dunne
12/4/19, 10:30 AM
Resurgent asymptotics unifies perturbative and non-perturbative methods in quantum mechanics and quantum field theory, and gives a new perspective on phase transitions. I present an introduction to the basic ideas behind resurgence and several physical examples of phase transitions that can be probed this way, including the finite N approach to large N phase transitions. I also discuss new...
16. Power of ZN-twisted boundary condition ~Resurgence and Continuity~
Prof. Tatsuhiro Misumi
12/4/19, 11:30 AM
Quantum field theories on the circle-compactified spacetime are quite worth investigating in terms of finite-T physics, resurgence theory and volume independence. In particular, several evidences indicate that the compactified theories with ZN-twisted boundary condition maintain the vacuum structure of the original uncompactified theory. We discuss this property, called adiabatic continuity,...
11. Sign problem and the tempered Lefschetz thimble method
Prof. Masafumi Fukuma
12/4/19, 1:30 PM
The tempered Lefschetz thimble method (TLTM) [arXiv:1703.00861] is a parallel-tempering algorithm towards solving the numerical sign problem. It uses the flow time of the antiholomorphic gradient flow as a tempering parameter and is expected to tame both the sign and multimodal problems simultaneously. In this talk, after reviewing the TLTM, we apply the method to various problems, including...
13. Deep into the Amplituhedron
Prof. Jaroslav Trnka
12/4/19, 2:30 PM
22. Renormalon in compactified spacetime and relation with bion
Dr Hiromasa Takaura
12/4/19, 3:30 PM
Recently, it was conjectured that the perturbative ambiguity known as the renormalon is canceled against the nonperturbative semiclassical object called bion. This conjecture expects this kind of cancellation in the circle compactified spacetime, in which the bion solution is found, as a premise. To examine this conjecture, we study the renormalon structure in the compactified spacetime under...
23. Topological order in the color-flavor locked phase of (3+1)-dimensional U(N) gauge-Higgs system
Dr Ryo Yokokura
12/4/19, 3:45 PM
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...
24. Chiral vortical conductivity across a topological phase transition from holography
Dr Xuanting Ji
12/4/19, 4:00 PM
We study the chiral vortical conductivity in a holographic Weyl semimetal model, which describes a topological phase transition from the strongly coupled topologically nontrivial phase to a trivial phase. We focus on the temperature dependence of the chiral vortical conductivity where the mixed gauge-gravitational anomaly plays a crucial role. After a proper renormalization of the chiral...
25. Nuclear states and spectra in holographic QCD
Dr Yoshinori Matsuo
12/4/19, 4:15 PM
A new method to study nuclear physics via holographic QCD is proposed. Multiple baryons in the Sakai-Sugimoto background are described by a matrix model which is a low energy effective theory of D-branes of the baryon vertices. We study the quantum mechanics of the matrix model and calculate the eigenstates of the Hamiltonian. The obtained states are found to coincide with known nuclear and...
26. 2d 't Hooft anomaly, orbifolding, and boundary states
Dr Ken Kikuchi
12/4/19, 4:50 PM
We study anomalies for a discrete internal global symmetry $G$ in two-dimensional conformal field theories based on twisted torus partition functions. The 't Hooft anomaly of $G$ can be seen from the noncommutativity of two symmetry lines inserted along the nontrivial circles of two-torus and we propose a criterion to detect the 't Hooft anomaly, which agrees with the truncated modular...
27. Does Boundary Distinguish Complexities?
Dr Yoshiki Sato
12/4/19, 5:05 PM
Recently, Chapman et al. argued that holographic complexities for defects distinguish action from volume. Motivated by their work, we study complexity of quantum states in conformal field theory with boundary. In generic two-dimensional BCFT, we work on the path-integral optimization which gives one of field-theoretic definitions for the complexity. We also perform holographic computations of...
28. Wavefunctions and Yukawa couplings on Resolutions of C^N/Z_N Orbifolds
Dr Hajime Otsuka
12/4/19, 5:20 PM
We propose matter wavefunctions on resolutions of C^N/Z_N singularities with magnetic fluxes. In this talk, we first discuss the resolution of magnetized T^2/Z_N orbifold models. In the blow-down limit of T^2/Z_N orbifolds, the obtained wavefunctions of chiral zero-modes result in those on the magnetized T^2/Z_N orbifold models, but only the wavefunctions of Z_N-invariant zero-modes receive...
29. String Geometry Phenomenology
Prof. Matsuo Sato
12/4/19, 5:35 PM
String geometry theory is one of candidates of the non-perturbative formulation of string theory. In order to derive low-energy phenomena, we first need to clarify how supergravity background fields, which represent the space-time and the internal space, are described in string geometry theory. In this presentation, we show that arbitrary configurations of the heterotic supergravity background...
14. Scattering Amplitudes from Geometries at Infinity
Prof. Song He
12/5/19, 9:30 AM
12. QCD phase diagram and the possibility of topological phases
Prof. Yoshimasa Hidaka
12/5/19, 10:30 AM
I discuss possible phases of QCD at finite temperature, density and/or strong fields. In particular, I discuss the possibility of topological phases in dense QCD matter.
34. S-duality for gauged Argyres-Douglas theories
Prof. Takahiro Nishinaka
12/5/19, 11:30 AM
30. Hyperbolic Field Space and Swampland Conjecture for DBI Scalar
Dr Yun-Long Zhang
12/5/19, 1:30 PM
We study a model of two scalar fields with a hyperbolic field space and show that it reduces to a single-field Dirac-Born-Infeld (DBI) model in the limit where the field space becomes infinitely curved. We apply the de Sitter swampland conjecture to the two-field model and take the same limit. It is shown that in the limit, all quantities appearing in the swampland conjecture remain...
31. Duality Invariance of Kahler potentials on Generalized Flag Manifolds from Diverse Quiver Gauge Theories
Dr Keisuke Ohashi
12/5/19, 1:45 PM
We present a systematic construction of K¨ahler potentials for various quiver gauge theories, which give pure realizations of the general flag manifolds as target manifolds. There, for arbitrary gener- alized flag manifolds with arbitrary complex structures, we rediscover the K¨ahler potentials given in the basic theory by Bando, Kuramoto, Maskawa and Uehara. In terms of these explicit forms,...
32. Direct Calculation of Mutual Information of Distant Regions
Dr Noburo Shiba
12/5/19, 2:00 PM
We consider the (Renyi) mutual information, I^(n) (A,B)=S^(n)_A +S^(n)_B −S^(n)_ A∪B , of distant compact spatial regions A and B in the vacuum state of a free scalar field. The distance r between A and B is much greater than their sizes R A,B . It is known that I^(n)_(A,B)∼C^(n)_AB ⟨0|ϕ(r)ϕ(0)|0⟩^2 . We obtain the direct expression of C^(n)_AB for arbitrary regions A and B. We perform the...
33. Quantum null energy condition, weak cosmic censorship, and holography
Dr Akihiro Ishibashi
12/5/19, 2:15 PM
We discuss the compatibility of AdS/CFT duality with the bulk and boundary causality which asserts that the fastest null geodesic connecting any two boundary points must lie entirely on the boundary. We show that if this type of causality fails without breaking the averaged null energy condition (ANEC), the weak cosmic censorship must be violated. We also discuss relationships between the bulk...
35. A possible solution to the black hole puzzle in semi-classical gravity
Prof. Takeshi Morita
12/5/19, 3:00 PM
We discuss that the black hole geometry around the event horizon in semi-classical gravity could be significantly different from that of the classical one. This is due to the Hawking radiation of the higher angular momentum modes of matter fields that was believed to be irrelevant.
59. Application of the tensor renormalization group method to non-Abelian lattice gauge theories
Mr Atis Yosprakob
12/5/19, 3:00 PM
The tensor renormalization group method is a powerful tool to study lattice models, which works even with models that have sign problem. However, so far, its application to gauge theory has been restricted the U(1) and SU(2) cases. In this work, we apply it to two-dimensional U(N) gauge theories which are exactly solvable. We are able to extract the large-N behaviors of the model such as...
39. Cancellation of one-loop corrections to scalar masses in Yang-Mills theory with flux compactification
Mr Takuya Hirose
12/5/19, 3:00 PM
We calculate one-loop corrections to the mass for the zero mode of scalar field in a six-dimensional Yang-Mills theory compactified on a torus with magnetic flux. It is shown that these corrections are exactly cancelled thanks to a shift symmetry under the translation in extra spaces. This result is expected from the fact that the zero mode of scalar field is a Nambu-Goldstone boson of the...
47. Complex Langevin Simulation of 2D U(1) gauge theory with a theta term
Mr Akira Matsumoto
12/5/19, 3:00 PM
The Monte Carlo simulation of gauge theories with a theta term is quite difficult due to the sign problem. The complex Langevin method is a promising approach to solve this problem. We applied this method to the 2D U(1) gauge theory, which is analytically solvable, in order to check the validity of the method. We were able to reproduce the exact results in the whole region of -pi <= theta <=...
60. Complex Langevin simulation of the Lorentzian type IIB matrix model
Mr Mitsuaki HIRASAWA (SOKENDAI)
12/5/19, 3:00 PM
The type IIB matrix model has been studied as a candidate of non-perturbative formulation of superstring theory. In particular, by Monte Carlo simulation of the Lorentzian type IIB matrix model, (3+1)-dimensional expanding space-time was shown to emerge dynamically. With its detailed analysis, we found that the emergent 3-dimensional space is essentially described by the Pauli matrices, we...
51. Complex poles and spectral functions of Landau gauge QCD and QCD-like theories
Ms Yui Hayashi
12/5/19, 3:00 PM
We investigate the analytic structures of the gluon and quark propagators of an effective model of the Landau gauge QCD and QCD with many quark flavors, which can be obtained by adding effective mass terms to the standard Faddeev-Popov Lagrangian. We derive general relationships between the number of complex poles and the sign of the spectral function under some assumptions on the asymptotic...
38. Cubic vertices for massless higher spin gauge fields in AdS spaces
Mr Haruya Suzuki
12/5/19, 3:00 PM
Higher spin (HS) gauge theory may be regarded as a generalization of the electromagnetic theory of a spin-1 photon and the linearized gravity of a spin-2 graviton. String theory which has infinitely many massive modes may be seen as a broken phase of the HS gauge symmetry. The higher spin gauge theory is expected to gain a deeper understanding of AdS/CFT duality. To gain more insight into the...
41. D3-brane analysis for the superconformal index in orbifold quiver gauge theories
Mr Shota Fujiwara
12/5/19, 3:00 PM
We study the orbifold type of AdS5/CFT4 correspondence for finite N by using the superconformal index. Especially, we calculate the finite N corrections to the superconformal index from the dual gravity theory. Our method is based on the assumption that D3-branes wrapped around three-cycles in the internal space reproduce the finite N corrections. As a result we find this approach actually gives...
49. Double field inflation of generalized dilaton-axion models with a new Fayet-Iliopoulos (FI) term
Mr Ping Kwan Man
12/5/19, 3:00 PM
In this talk, we are going to talk about inflation dynamics by KKLT-like model modified by a new Fayet-iliopoulos (FI) term. KKLT model, motivated by superstring theory, gives the AdS vacuum, which is phenomenologically forbidden. Although previous studies solved this problem by adding a D3 bar or D7 contribution to uplift the vacuum to zero, it is not flat enough to provide the initial...
45. Dynamics of Revolving D-Branes at Short Distances
Mr Hikaru Ohta
12/5/19, 3:00 PM
We study the behavior of the effective potential between revolving Dp-branes at all ranges of the distance $r$, interpolating regions on which r is larger and smaller than the string length. Since the one-loop open string amplitude cannot be calculated exactly, we instead employ an efficient method of partial modular transformation. The method is to perform the modular transformation partially...
50. Emergent quantum spacetime from stochastic processes of matrix models
Mr Nobuyuki Matsumoto
12/5/19, 3:00 PM
Towards formulating quantum gravity, we present a mechanism of the emergence of spacetime geometry from randomness. In [Fukuma-NM-Umeda, [arXiv:1705.06097]], we defined for a given stochastic process "the distance between configurations," which enumerates the difficulty of transition. In this talk, we consider large-N matrix models, in which we regard eigenvalues as spacetime coordinates. We...
57. Entropy generation and decay of the cosmological constant in Liouville gravity
Dr Kitamoto Hiroyuki
12/5/19, 3:00 PM
We investigated quantum infrared dynamics in 2D Liouville gravity with a positive cosmological constant and a large central charge $c>25$. Superhorizon fluctuations of the conformal mode of the metric dynamically screen the cosmological constant, and the dS entropy increases simultaneously. We can identify the dS entropy with the von Neumann entropy of the conformal zero mode. This quantum...
42. Finite N corrections to the superconformal index of toric quiver gauge theories
Mr Tatsuya Mori
12/5/19, 3:00 PM
We study the finite N AdS/CFT correspondence between the Type IIB string theories on AdS5×SE5 and quiver gauge theories, where SE5 is a five-dimensional Sasaki-Einstein manifold. Our assumption is that D3-branes wrapping on the three-cycles in the internal space give the finite N corrections to the index. We calculate the index of wrapped D3-branes and get the non-trivial coincidence for...
54. From 3d dualities to hadron physics
Mr Naoto Kan
12/5/19, 3:00 PM
When one of the space-time dimension is compactified on the circle, the QCD exhibits the chiral phase transition at some critical radius. When we further turn on a background theta term which depends on the compactified coordinate, a topological ordered phase appears at low energy via the winding of the theta. We discuss what kind of theories can describe the physics near the critical point by...
40. Higher spin symmetry in the IIB matrix model with the operator interpretation
Mr Katsuta Sakai
12/5/19, 3:00 PM
We study the IIB matrix model in an interpretation where the matrices are differential operators defined on curved spacetimes. In this interpretation, coefficients of higher derivative operators formally appear to be massless higher spin fields. With my poster, we discuss whether the unitary symmetry of the matrices includes appropriate higher spin gauge symmetries. We find that the additional...
46. How information geometry is encoded in bulk geometry
Mr Kazushi Yamashiro
12/5/19, 3:00 PM
We study how information geometry is described by bulk geometry in the gauge/gravity correspondence. We consider a quantum information metric that measures the distance between the ground states of a CFT and a theory obtained by perturbing the CFT. Using the GKP-Witten relation, we find a universal formula that expresses the quantum information metric by a geometrical quantity in a...
36. Infrared renormalon in the supersymmetric $\mathbb{C}P^{N-1}$ model on $\mathbb{R}\times S^1$
Mr Okuto Morikawa
12/5/19, 3:00 PM
In the leading order of the large $N$ approximation, we study the renormalon ambiguity in the gluon (or more appropriately, photon) condensate in the two-dimensional supersymmetric $\mathbb{C}P^{N-1}$ model on $\mathbb{R}\times S^1$ with the $\mathbb{Z}_N$ twisted boundary conditions. In our large $N$ limit, the combination $\Lambda R$, where $\Lambda$ is the dynamical scale and $R$ is the...
43. Instability of Higgs Vacuum via String Cloud
Mr Issei Koga
12/5/19, 3:00 PM
We study the instability of the Higgs vacuum caused by a cloud of strings. By the catalysis, the decay rate of the vacuum is highly enhanced and when the energy density of the cloud is larger than the critical value, the semi-classical vacuum decay occurs. We also discuss the relation between the cloud of strings and observational constraints on cosmic strings in terms of the catalysis,...
55. Localization of gauge field on 3-branes and Higgs mechanism
Mr Masaki Kawaguchi
12/5/19, 3:00 PM
We provide complete and self-contained formulas about localization of massless/massive Abelian gauge fields on topological solitons in generic D dimensions via a field dependent gauge kinetic term. The localization takes place when a stabilizer (a scalar field) is condensed in the topological soliton. We show that the localized gauge bosons are massless when the stabilizer is neutral. On the...
48. On UV-finiteness of supersymmetric gradient flow in N=1 SQCD
Mr Mitsuyo Suzuki
12/5/19, 3:00 PM
I will discuss perturbation theory of supersymmetric gradient flow in 4D N = 1 SQCD. The perturbation theory consists of a perturbative expansion of 4D SQCD and an iterative expansion of the flow equation. In order to prove UV-finiteness of flow theory, it is necessary to calculate its correlation functions and to construct a d+1-dimensional theory which reproduces the same perturbation series.
37. Sign flip triangulation of the 1-loop NMHV amplituhedron
Mr Ryota Kojima
12/5/19, 3:00 PM
In this talk, I will talk about the triangulation of the amplituhedron. To obtain higher point amplitude from the general amplituhedron, we need to triangulate it into a simple one. There is some way to triangulate the amplituhedron and some of this gives new representations of the amplitude. I will briefly explain the amplituhedron and its property, then I will talk about the new...
44. Superconformal index and supersymmetry enhancement of S-fold theories
Mr Reona Arai
12/5/19, 3:00 PM
Recently concrete models of 4d N=3 superconformal field theories called S-fold theories are constructed by Garcia-Etxebarria and Regalado. Although it is difficult to study these theories due to the lack of the Lagrangian description and the strong coupling, it is expected that there is a non-trivial supersymmetry enhancement for rank one and two theories by Aharony and Tachikawa. In this...
53. Tricritical point and non-equilibrium phase transition in gauge gravity duality
Mr Masataka Matsumoto
12/5/19, 3:00 PM
We study the phase structure associated with the chiral symmetry in the D3-D7 model. We find the non-equilibrium phase transition for massless quarks in the presence of a constant current and a magnetic field. This non-equilibrium phase transition is related to the chiral symmetry breaking. We also discover the tricritical point in the phase diagram.
52. TT-bar deformation in large N limit
Mr Junichi Haruna
12/5/19, 3:00 PM
We consider two dimensional TT-bar deformed O(N) invariant massive scalar theory in large N limit, and investigate its renormalizability at 1/N ( next to leading ) level. As a result, we find that we need to renormalize the deformation parameter at leading level, and non-local counterterms at 1/N (next to leading) level. Also we find that positivity of state space is violated in the UV region...
61. Unitary matrix model with the logarithmic potential
Mr Hitomi TASHIRO (SOKENDAI)
12/5/19, 3:00 PM
We study the unitary one-matrix model with the logarithmic potential. It has been known that a hermitian one-matrix model with a logarithmic potential yields the prepotential of 4d N=2 SU(2) SUSY gauge theory as its large-N free energy. We give a rigorous proof that the unitary matrix model with the potential of the same form as the hermitian matrix model for 4d N=2 Nf=2 SU(2) SUSY gauge...
15. Swampland Phenomenology
Prof. Masahito Yamazaki
12/6/19, 9:30 AM
10. Anomaly matching in QCD thermal phase transition
Prof. Kazuya Yonekura
12/6/19, 10:30 AM
I will talk about a nonperturbative constraint on QCD thermal phase transition. First, I discuss a rigorous constraint from 't Hooft anomaly matching when the quarks are massless and we introduce an imaginary baryon chemical potential at the Roberge-Weiss point. Then, I discuss the reason why I think the constraint is also relevant for the QCD phase transition without any imaginary chemical...
17. Asymptotic Freedom in de Sitter Space
Prof. Yoshihisa Kitazawa
12/6/19, 11:30 AM
We investigate infrared dynamics of four-dimensional Einstein gravity in de Sitter space. With the accelerated expansion of the universe, conformal zero modes accumulate at the horizon. The inflaton reresent the characteristic scale of the zero mode distribution. Furthermore, the introduction of an inflaton in the low energy effective theory is necessary to preserve Lorentz symmetry. We...
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