# KEK Theory workshop 2019

3-6 December 2019
KEK
Japan timezone
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## Contribution List

Displaying 54 contributions out of 54
Session: Short talks
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 $S$-matrix ... More
Presented by Dr. Ken KIKUCHI on 4 Dec 2019 at 16:50
Session: Poster
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.
Presented by Prof. Takeshi MORITA on 5 Dec 2019 at 15:00
Session: Invited talks
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 renorm ... More
Presented by Prof. Nobuyoshi OHTA on 3 Dec 2019 at 13:30
Session: Invited talks
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 potent ... More
Presented by Prof. Kazuya YONEKURA on 6 Dec 2019 at 10:30
Session: Invited talks
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 observe an ... More
Presented by Prof. Yoshihisa KITAZAWA on 6 Dec 2019 at 11:30
Session: Poster
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 transla ... More
Presented by Mr. Takuya HIROSE on 5 Dec 2019 at 15:00
Session: Short talks
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 bubble ... More
Presented by Prof. Yutaka OOKOUCHI on 3 Dec 2019 at 14:45
Session: Short talks
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 vortical ... More
Presented by Dr. Xuanting JI on 4 Dec 2019 at 16:00
Session: Poster
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 <= pi by ... More
Presented by Mr. Akira MATSUMOTO on 5 Dec 2019 at 15:00
Session: Poster
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 behav ... More
Presented by Ms. Yui HAYASHI on 5 Dec 2019 at 15:00
Session: Poster
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 dual ... More
Presented by Mr. Haruya SUZUKI on 5 Dec 2019 at 15:00
Session: Poster
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 give ... More
Presented by Mr. Shota FUJIWARA on 5 Dec 2019 at 15:00
Session: Invited talks
Presented by Prof. Jaroslav TRNKA on 4 Dec 2019 at 14:30
Session: Short talks
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 ... More
Presented by Dr. Noburo SHIBA on 5 Dec 2019 at 14:00
Session: Short talks
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 the ... More
Presented by Dr. Yoshiki SATO on 4 Dec 2019 at 17:05
Session: Short talks
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, we ... More
Presented by Dr. Keisuke OHASHI on 5 Dec 2019 at 13:45
Session: Poster
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 in ... More
Presented by Mr. Hikaru OHTA on 5 Dec 2019 at 15:00
Session: Poster
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 defin ... More
Presented by Mr. Nobuyuki MATSUMOTO on 5 Dec 2019 at 15:00
Session: Short talks
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 dualit ... More
Presented by Prof. Yasuhiro SEKINO on 3 Dec 2019 at 15:00
Session: Poster
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 leading ... More
Presented by Mr. Tatsuya MORI on 5 Dec 2019 at 15:00
Session: Poster
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 req ... More
Presented by Mr. Naoto KAN on 5 Dec 2019 at 15:00
Session: Short talks
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 gravitational p ... More
Presented by Mr. Anand HEGDE on 3 Dec 2019 at 14:30
Session: Poster
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 aux ... More
Presented by Mr. Katsuta SAKAI on 5 Dec 2019 at 15:00
Session: Poster
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 back-reacted bu ... More
Presented by Mr. Kazushi YAMASHIRO on 5 Dec 2019 at 15:00
Session: Short talks
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 well-defined w ... More
Presented by Dr. Yun-Long ZHANG on 5 Dec 2019 at 13:30
Session: Invited talks
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 space s ... More
Presented by Prof. Hiroshi SUZUKI on 4 Dec 2019 at 09:30
Session: Poster
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 slow-roll ... More
Presented by Mr. Ping Kwan MAN on 5 Dec 2019 at 15:00
Session: Poster
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 $S^1$ r ... More
Presented by Mr. Okuto MORIKAWA on 5 Dec 2019 at 15:00
Session: Poster
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, providing ... More
Presented by Mr. Issei KOGA on 5 Dec 2019 at 15:00
Session: Poster
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 other ... More
Presented by Mr. Masaki KAWAGUCHI on 5 Dec 2019 at 15:00
Session: Short talks
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 baryon ... More
Presented by Dr. Yoshinori MATSUO on 4 Dec 2019 at 16:15
Session: Poster
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.
Presented by Mr. Mitsuyo SUZUKI on 5 Dec 2019 at 15:00
Session: Invited talks
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.
Presented by Prof. Yoshimasa HIDAKA on 5 Dec 2019 at 10:30
Session: Invited talks
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.
Presented by Prof. Hikaru KAWAI on 3 Dec 2019 at 10:30
Session: Short talks
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 and ... More
Presented by Dr. Akihiro ISHIBASHI on 5 Dec 2019 at 14:15
Session: Short talks
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 the ... More
Presented by Dr. Hiromasa TAKAURA on 4 Dec 2019 at 15:30
Session: Invited talks
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 resurge ... More
Presented by Prof. Gerald DUNNE on 4 Dec 2019 at 10:30
Session: Invited talks
Presented by Prof. Takahiro NISHINAKA on 5 Dec 2019 at 11:30
Session: Invited talks
Presented by Prof. Song HE on 5 Dec 2019 at 09:30
Session: Poster
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 representation o ... More
Presented by Mr. Ryota KOJIMA on 5 Dec 2019 at 15:00
Session: Invited talks
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 the q ... More
Presented by Prof. Masafumi FUKUMA on 4 Dec 2019 at 13:30
Session: Invited talks
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.
Presented by Dr. Masatoshi YAMADA on 3 Dec 2019 at 11:30
Session: Short talks
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 fie ... More
Presented by Prof. Matsuo SATO on 4 Dec 2019 at 17:35
Session: Invited talks
String model building has made considerable progress over the past decade and models with the precise (MS)SM spectrum can now be readily engineered. However, a true string standard model is still some what off, due to the conceptual and technical difficulties in reproducing the correct coupling constants. I will review some of the progress in model building and the attempts to calculate fermion ma ... More
Presented by Prof. Andre LUKAS on 4 Dec 2019 at 11:30
Session: Poster
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 poster, ... More
Presented by Mr. Reona ARAI on 5 Dec 2019 at 15:00
Session: Short talks
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 quad ... More
Presented by Dr. Sota HANAZAWA on 3 Dec 2019 at 15:15
Session: Invited talks
Presented by Prof. Masahito YAMAZAKI on 6 Dec 2019 at 09:30
Session: Poster
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 even ... More
Presented by Mr. Junichi HARUNA on 5 Dec 2019 at 15:00
Session: Short talks
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 pha ... More
Presented by Dr. Ryo YOKOKURA on 4 Dec 2019 at 15:45
Session: Poster
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.
Presented by Mr. Masataka MATSUMOTO on 5 Dec 2019 at 15:00
Session: Short talks
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 the bl ... More
Presented by Dr. Hajime OTSUKA on 4 Dec 2019 at 17:20