# KEK Theory workshop 2018

17-20 December 2018
Kenkyu-Honkan bldg. 1F
Japan timezone
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## Contribution List

Displaying 58 contributions out of 58
Session: Invited talks
Presented by Prof. Shigeki SUGIMOTO on 20 Dec 2018 at 09:30
Session: Poster session
Board #: 19
We propose a novel gauge-invariant regularization for the perturbative chiral gauge theory. We describe a chiral fermion as the massless mode of the domain-wall fermion. There we can regularize both the parity-odd and even part of the fermion loops by introducing the Pauli-Villars regulators. On the other hand, loops involving the gauge field are regularized by applying the dimensional regularizat ... More
Presented by Mr. Katsuta SAKAI on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 17
We attempt to describe baryons based on gauge/gravity correspondence. In particular, we focus on baryon excited states and employ D4/D8-brane model, which is not still investigated in detail from this point of view. First, we take the limit where the effect of the curved background is negligible and then study the spectrum of strings in the flat spacetime. After that we attempt to incorporate pert ... More
Presented by Mr. Takahiro OGINO on 19 Dec 2018 at 15:00
Session: Invited talks
I would like to given an overview of the recent development of string field theory.
Presented by Prof. Nobuyuki ISHIBASHI on 18 Dec 2018 at 14:40
Session: Poster session
Board #: 28
We discuss some classical solutions of type IIB matrix model that generate chiral fermions, which is essential for realizing the Standard Model. In particular, we consider solutions constructed from representations of special unitary groups' generators. Fermion wave functions can then be generated as eigenvectors of the associated matrix Dirac operator. It is found that many solutions give large n ... More
Presented by Mr. Atis YOSPRAKOB on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 22
I consider a two-parameter family of higher-derivative gravitational actions exhibiting T-duality. Some values of the parameters correspond to string theory effective actions, but most of them do not. For all cases, I will show black hole entropy and temperature to be invariant under T-duality. As an explicit example, BTZ black hole and its T-dual black string are presented.
Presented by Dr. J. Anibal SIERRA-GARCIA on 19 Dec 2018 at 15:00
Session: Short talks
We revisit CFTs by studying those on curved metric spaces, both orientable and unorientable possibly with boundaries.
Presented by Dr. Ken KIKUCHI on 18 Dec 2018 at 16:05
Session: Poster session
Board #: 18
AdS/CFT correspondence tells us that the energy of an open string hanging on the boundary of a curved spacetime is equivalent to the Wilson loop in the gauge theory side. In general, the motion of a string in a curved background shows chaotic behavior. Then, how is the chaos seen in observables in a QFT? We study the dynamics of an open string in the D4-soliton geometry which corresponds to a pure ... More
Presented by Mr. Toshihiro OTA on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 6
We derive a relation between the number of complex poles of a propagator and some behavior of the spectral function assuming the behavior of the propagator in the neighborhood of the origin and the asymptotically large region in the complex momentum plane. We apply this relation to the mass-deformed Yang-Mills model, which is identified with a low-energy effective theory of the Yang-Mills theory, ... More
Presented by Ms. Yui HAYASHI on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 25
We construct three-point functions with spinning operators in momentum space by explicitly solving the conformal Ward-Takahashi identities. In particular we demonstrate that they can be obtained by acting some differential operators on scalar three-point functions. We expect that our results are useful, e.g., for the Polyakov type bootstrap approach and study of cosmological correlation functions. ... More
Presented by Mr. Toshiaki TAKEUCHI on 19 Dec 2018 at 15:00
Session: Invited talks
I first explain that the classical scale invariance is a necessary condition for the calculability of the vacuum energy. Then, I discuss how sufficient the scale invariance is for solving the cosmological constant problem as well as the gauge hierarchy problem.
Presented by Prof. Taichiro KUGO on 17 Dec 2018 at 15:10
Session: Poster session
Board #: 8
Recently, we have investitated Unruh effect for closed strings and for open strings on D9-brane--anti-D9-brane pairs, and discuss the creation of D9-brane--anti-D9-brane pairs for highly accelerated observers. In this talk, we consider a simple time dependent background, in which the spacetime becomes Minkowski spacetime in the far past and future, and investigate the Hawking-Unruh effect of open ... More
Presented by Dr. Kenji HOTTA on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 15
Fuzzy spaces are known as a typical example of noncommutative geometry and expected to describe the fundamental structure of space-time. However, the mechanism to describe gravity in the framework of fuzzy spaces remains to be completely elucidated. In order to understand the mechanism, we focus on the notion of diffeomorphisms, which plays a key role in the classical theory of gravity. In this ta ... More
Presented by Dr. Takashi MATSUMOTO on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 5
We numerically investigate whether chiral zero modes appear in the IIB matrix model, which is known as one of non-perturbative formulations of superstring theory. We examine the spectrum of the 6-dimensional Dirac operator for classical solutions of the IIB matrix model, and we find that there exist non-trivial zero modes and the corresponding wave functions are localized. We discuss that these ze ... More
Presented by Mr. Kohta HATAKEYAMA on 19 Dec 2018 at 15:00
Session: Short talks
An idea to formulate string theory or M-theory by a gauge theory attracts theorists and has been extensively studied. The gauge theory should be lower dimensional so that a geometry in string or M-theory, which has higher dimensions, must emerge from it. This suggests that there would be a phase transition in the gauge theory and that the geometry should appear as its temperature decreases. In thi ... More
Presented by Dr. Yuhma ASANO on 18 Dec 2018 at 16:35
Session: Short talks
In the expanding universe, two interacting fields are no longer in thermal contact when the interaction rate becomes smaller than the Hubble expansion rate. After decoupling, two subsystems are usually treated separately in accordance with equilibrium thermodynamics and the thermodynamic entropy gives a fiducial quantity conserved in each subsystem. In this paper, we discuss a correction to this p ... More
Presented by Dr. Noburo SHIBA on 18 Dec 2018 at 17:20
Session: Invited talks
We prove that there is an open string in the spectrum of holographic Fermion coupled with a scalar. The string ends at two fermions and its tension vanishes in the limit of zero scalar condensation. We call it “entanglement string”. The model shows a Mott transition so that together with divergently large entanglement entropy, our model is qualified to describe the Resonating Valence Bond ... More
Presented by Prof. Sang-Jin SIN on 19 Dec 2018 at 10:40
Session: Poster session
Board #: 3
Neutron detectors are vital devices used in various fields like nuclear power, nuclear medicine, particle physics, etc. In the present work, pure europium oxide (Eu2O3) shows the remarkable results for thermal neutron detection. The natural thermal neutron source Cf-252 having flux 106 n/sec/cm2 was used for irradiation of Eu2O3 samples. All the thermal neutron fluences were measured in ex-situ ti ... More
Presented by Dr. Mahesh Sakharam BHADANE on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 26
We have found that the N-extended quantum mechanical supersymmetry with central charges is hidden in the 4D mass spectrum of higher dimensional Dirac field. The supercharges tell us a relationship among the Kaluza-klain (KK) mode functions with degenerate 4D mass eigenvalues due to the degrees of freedom of the higher dimensional spinor. Furthermore, we focus on the BPS states which form the short ... More
Presented by Mr. Inori UEBA on 19 Dec 2018 at 15:00
Session: Invited talks
Presented by Prof. Tatsuo KOBAYASHI on 17 Dec 2018 at 14:00
Session: Short talks
We propose that the fracton topological order is a class of toy models for holography. The discovery of AdS/CFT correspondence as a concrete construction of holography, and the subsequent developments including the Ryu-Takanayagi formula of entanglement entropy have revolutionized our understanding of quantum gravity, and provided a powerful tool set for solving various strongly-coupled quantum fi ... More
Presented by Mr. Han YAN on 19 Dec 2018 at 11:45
Session: Invited talks
The gauge symmetry breaking in string models with D-branes is discussed. Starting from a simple argument that the parallel separation of D-branes exhibits spontaneous gauge symmetry breaking, the mechanism of rank reduction of gauge group, which is necessary for realistic electroweak symmetry breaking, is discussed. The mechanism for a fixed stable scale of gauge symmetry breaking, which is necess ... More
Presented by Prof. Noriaki KITAZAWA on 18 Dec 2018 at 10:40
Session: Invited talks
Recently, there has been a fundamental and significant development in the Green-Schwarz (GS) formulation of superstring theory. In this formulation, the kappa-symmetry plays a central role to ensure the consistency of the theory. In 2016, Tseytlin and Wulff showed that the kappa-symmetry constraints of the GS superstring defined on an arbitrary background lead to a generalized'' supergravity, wh ... More
Presented by Prof. Kentaroh YOSHIDA on 20 Dec 2018 at 10:30
Session: Poster session
Board #: 12
Nima arkani-Hamed and Jaroslav trnka found a new mathematical object, "the Amplituhedron" that its 'volume' is the amplitude in planar N=4 SYM. We found a new explicit formula for the n-pt 2-loop MHV amplitude from the amplituhedron and obtain some properties of the amplitude from this result. In this talk, I will briefly explain the definition of the amplituhedron and our results about a geometr ... More
Presented by Mr. Ryota KOJIMA on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 24
In this poster, we investigate zero and one dimensional Hermitian matrix models with cusp potentials at large N. We show that large N phase transitions in these models are quite different from the third order phase transitions in the ordinary polynomial potential cases. Particularly the zero dimensional matrix models exhibit unexpected behaviors.
Presented by Mr. Kento SUGIYAMA on 19 Dec 2018 at 15:00
Session: Short talks
O(α') corrections in 10D heterotic supergravity are known to give nontrivial contributions compared to its type IIA/IIB counterparts. By using a conformal factor ansatz that is valid only for geometries of 2 complex (4 real) dimensions, we obtained a closed expression for the metric correction in the case of several orbifold limits of K3, namely T^4/Z_n where n=2,3,4,6. Furthermore, we numericall ... More
Presented by Mr. Hon Yin LEUNG on 17 Dec 2018 at 17:20
Session: Short talks
We investigate three-form gauge theories with higher derivative interactions and their supersymmetric extensions in four space-time dimensions. For the bosonic three-form gauge theories, we show that derivatives on the field strength of the 3-form gauge field yield a tachyon as far as the Lagrangian contains a quadratic kinetic term, while such the term with opposite sign gives rise to a ghost. We ... More
Presented by Ryo YOKOKURA on 18 Dec 2018 at 17:05
Session: Short talks
We discuss a scenario that the dark matter fluid in late time universe emerges as part of the holographic stress-energy tensor on the hypersurface in higher dimensional flat spacetime. We construct a toy model with the Friedmann-Lemaitre-Robertson-Walker (FLRW) hypersurface as the holographic screen in the flat bulk. After adding the baryonic matter on the screen, we assume that both of the dark m ... More
Presented by Dr. Yun-Long ZHANG on 17 Dec 2018 at 16:50
Session: Invited talks
First we explain our recent conjecture that a gravity dual of a quantity called entanglement of purification is given by the minimal area of entanglement wedge cross section in AdS. This provides a simple generalization of holographic entanglement entropy to mixed states. Then we argue that in AdS3/CFT2 setups, the holographic entanglement of purification agrees with the entanglement entropy in a ... More
Presented by Prof. Tadashi TAKAYANAGI on 19 Dec 2018 at 09:30
Session: Invited talks
I argue that the Anti-de-Sitter (AdS) geometry in $d+1$ dimensions naturally emerges from an arbitrary conformal field theory in $d$ dimensions using the free flow equation. I first show that an induced metric defined from the flowed field generally corresponds to the quantum information metric, called the Bures or Helstrom metric, if the flowed field is normalized appropriately. I next verify tha ... More
Presented by Prof. Sinya AOKI on 20 Dec 2018 at 11:30
Session: Short talks
New inflationary models in supergravity with the Dirac-Born-Infeld type kinetic terms and new Fayet-Iliopoulos-type terms are constructed. These models can be considered as the string-inspired deformations of Starobinsky inflationary model in supergravity. Their phenomenological applications are briefly discussed.
Presented by Prof. Sergey KETOV on 19 Dec 2018 at 12:00
Session: Poster session
Board #: 7
Inflation is a promising scenario of the early Universe and it can explain cosmological observations of CMB. Although there are a lot of models for the inflation, recently it is possible to restrict them by comparing cosmological parameters with the observations. We investigate inflationary cosmology by solving the effective action of the M-theory, which consists of the 11 dimensional supergravity ... More
Presented by Mr. Kazuho HIRAGA on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 27
We study the Liouville irregular states proposed by Gaiotto and Teschner, and evaluate irregular conformal blocks corresponding to the Nekrasov partition functions of the (A1,D4) and (A1,A3) Algyres-Douglas theories. The salient feature of this calculation is that we discuss the Q-dependence of Nekrasov partition function in the 2d-4d relation. Q is the Liouville charge and corresponds to a parame ... More
Presented by Mr. Takahiro UETOKO on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 11
We study a localization mechanism of gauge fields on a 3-brane in Yang-Mills-Higgs models with a modified kinetic term of gauge fields in non-compact extra dimensions (D&gt;4). The localization mechanism is carried out when the Higgs field locally condenses on the 3-brane. Hence, the Higgs mechanism yields, in addition to two conventional roles (spontaneous symmetry breaking of the gauge symmetry ... More
Presented by Masaki KAWAGUCHI on 19 Dec 2018 at 15:00
Session: Short talks
IKKT model was proposed as a non-perturbative formulation of superstring theory. We propose a Dirac operator on the noncommutative torus, which is consistent with IKKT model, based on noncommutative geometry. In addition, we consider zero-mode equations of our Dirac operator with magnetic fluxes. We find that zero-mode solutions have chirality and generation structures similar to the commutative c ... More
Presented by Mr. Masaki HONDA on 18 Dec 2018 at 16:20
Session: Poster session
Board #: 10
We construct a crossing symmetric basis for conformal four-point functions in momentum space by requiring consistent factorization. Just as scattering amplitudes factorize when the intermediate particle is on-shell, non-analytic parts of conformal correlators enjoy a similar factorization in momentum space. Based on this property, Polyakov, in his pioneering 1974 work, introduced a basis for confo ... More
Presented by Dr. Hiroshi ISONO on 19 Dec 2018 at 15:00
Session: Invited talks
Presented by Prof. Hikaru KAWAI on 18 Dec 2018 at 09:30
Session: Poster session
Board #: 16
It is believed that the two-dimensional massless $\mathcal{N}=2$ Wess--Zumino model becomes the $\mathcal{N}=2$ SCFT in the IR limit. We examine this theoretical conjecture of the Landau--Ginzburg (LG) description of the $\mathcal{N}=2$ SCFT by numerical simulations on the basis of a supersymmetric-invariant momentum-cutoff regularization. We study one or two supermultiplets with various superpote ... More
Presented by Mr. Okuto MORIKAWA on 19 Dec 2018 at 15:00
Session: Short talks
Let us consider Lovelock theory of gravity in higher dimensional spacetime and compactify extra dimensions with a variety of symmetric Riemann manifolds. In those cases, stability of size moduli of such internal spaces need non-vanishing higher-order Lovelock terms higher than the quadratic term. That is, a dimension of the internal space must be larger than or equal to six.
Presented by Dr. Keisuke OHASHI on 17 Dec 2018 at 16:35
Session: Poster session
Board #: 1
The type IIB matrix model was proposed as a non-perturbative formulation of superstring theory in 1997. The emergence of (3+1)-dimensional space-time was observed in Monte Carlo studies of its Lorentzian version. This implies that an expanding (3+1)-dimensional space-time naturally appears from (9+1)-dimensional space-time, in which superstring theory is defined. The expanding behavior was studied ... More
Presented by Mr. Toshihiro AOKI on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 2
The type IIB matrix model has been studied as a 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. Moreover, from simulations of simplified models, it was suggested that the expansion of space is exponential at early times and it turns into a po ... More
Presented by Mr. Mitsuaki HIRASAWA on 19 Dec 2018 at 15:00
Session: Invited talks
We discuss moduli stabilization of the F-theory compactified on elliptically fibered Calabi-Yau fourfolds. We turn on appropriate G-fluxes to stabilize all the complex structure moduli fields, corresponding to the open and closed string moduli in the type IIB limit. It is found that they can be stabilized at the Minkowski or de Sitter minimum. We also discuss the swampland conjecture in the g ... More
Presented by Dr. Hajime OTSUKA on 17 Dec 2018 at 11:10
Session: Short talks
We propose a new mechanism of (geometric) moduli stabilisation in type IIB/F-theory four-dimensional compactifications on Calabi–Yau manifolds, in the presence of 7-branes, that does not rely on non-perturbative effects. Complex structure moduli and the axion-dilaton system are stabilised in the standard way, without breaking supersymmetry, using 3-form internal fluxes. Kähler class moduli stab ... More
Presented by Mr. Yifan CHEN on 17 Dec 2018 at 16:20
Session: Poster session
Board #: 23
Resurgence is a method to connect perturbative series with nonperturbative effect via Stokes phenomenon. In resurgence, Borel ambiguity should be cancelled but in bounce calculation, which shows the path integral itself has ambiguity, as a result we can the Borel ambiguity regarded as the bounce contribution itself. With this relation, I calculated higher corrections of bounce contribution from ... More
Presented by Mr. Naohisa SUEISHI on 19 Dec 2018 at 15:00
Session: Invited talks
Presented by Prof. Yoshio KIKUKAWA on 18 Dec 2018 at 13:30
Session: Short talks
We study operator entanglement measures of the unitary evolution operators of (1+1)-dimensional conformal field theories, aiming to uncover scrambling and chaotic behaviors thereof. In particular, we compute the bi-partite and tri-partite mutual in- formation for various configurations of input and output subsystems, and as a function of time. We contrast three different conformal field theories: ... More
Presented by Dr. Masahiro NOZAKI on 19 Dec 2018 at 11:30
Session: Poster session
Board #: 4
Berkovits and Pershin have shown that in a general background, the ten-dimensional Born-Infeld equations of motion for the background fields are extracted from BRS charge conservation in an open pure spinor superstring. We improve their result to include even contribution of Dirichlet boundary conditions for the open superstring. It is expected that the resulting abelian Born-Infeld equations cont ... More
Presented by Mr. Sota HANAZAWA on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 13
It was known that quantum curves and super Chern-Simons matrix models correspond to each other. From the viewpoint of symmetry, the algebraic curve of genus one, called the del Pezzo geometry, enjoys symmetries of the exceptional algebra, while the super Chern-Simons matrix model is described by the free energy of topological strings on the del Pezzo background with the symmetry broken. We study t ... More
Presented by Mr. Naotaka KUBO on 19 Dec 2018 at 15:00
Session: Short talks
We study a direct flux breaking scenario in all three heterotic string theroies on general Calabi-Yau (CY) threefolds. We show background independent formulae to construct three-generation models without chiral exotics from $SO(32)$, $SO(16)\times SO(16)$ and $E8\times E8$ heterotic string theories. In this talk, we show the algorithms to search the formulae and a concrete three-generation model o ... More
Presented by Mr. Kenta TAKEMOTO on 17 Dec 2018 at 17:35
Session: Poster session
Board #: 29
In the conformal field theory(CFT), there is a deformation of theory that does not change the original CFT’s symmetry, so called Exactly Marginal Deformation. The generator of this deformation is exactly marginal operator(EMO). The motivation of our study is to check the properties of exactly marginal operator with using AdS/CFT correspondence. The properties are the correlation functions of ... More
Presented by Mr. Masashi ZENKAI on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 20
Perturbative string amplitudes are correctly derived from the string geometry theory, which is one of the candidates of a non-perturbative formulation of string theory. In order to derive non-perturbative effects rather easily from the theory, we formulate topological string geometry theory, which is obtained by restricting the string geometry theory to its topological sector. Because string geome ... More
Presented by Prof. Matsuo SATO on 19 Dec 2018 at 15:00
Session: Short talks
We explore a C-theorem in defect conformal field theories (DCFT) that unify all the known conjectures and theorems until now. We examine as a candidate C-function the additional contributions from conformal defects to the sphere free energy and the entanglement entropy across a sphere in a number of examples including holographic models. We find the two quantities are equivalent, when suitably reg ... More
Presented by Dr. Kento WATANABE on 18 Dec 2018 at 16:50
Session: Short talks
In supersymmetric theories, the signs of quartic terms in the Kähler potential control the stability of non-supersymmetric field configurations. In particular, in supersymmetric inflation models, the signs are important for the stability of an inflationary trajectory as well as for the prediction of the spectral index. In this paper, we clarify what properties of a UV theory determine the ... More
Presented by Dr. Takahiro TERADA on 17 Dec 2018 at 17:05
Session: Poster session
Board #: 14
We derive the covariant holographic two-point functions and find that they have a universal structure. In particular, the theory-dependent overall coefficient C_{T} can be universally expressed by (d − 1)C_{T} = ℓ(∂a/∂ℓ), where a is the holographic a-charge. We verify this relation in quasitopological Ricci polynomial, Einstein-Gauss-Bonnet, Einstein-Lovelock and Einstein cubic grav ... More
Presented by Mr. Zhan-Feng MAI on 19 Dec 2018 at 15:00
Session: Poster session
Board #: 9
Localized Kaluza-Klein zero-mode wavefunctions are desired for extra dimensional models to explain the Yukawa hierarchy of the Standard Model of particle physics. This is why the magnetized S^2, which wavefunctions on are not localized, are phenomenologically unfavorable as extra dimensions. In this work, we revisit S^2 with introducing 3-branes in addition to magnetic flux. We derive wavefunctio ... More
Presented by Mr. Sosuke IMAI on 19 Dec 2018 at 15:00
Session: Invited talks
Presented by Prof. Sakura SCHAFER-NAMEKI on 17 Dec 2018 at 10:10
Session: Poster session
Board #: 21
We make a comprehensive study on the string winding corrections to supergravity solutions in double field theory (DFT). We find five-brane and wave solutions of diverse codimensions in which the winding coordinates are naturally included. We discuss a physical interpretation of the winding coordinate dependence. The analysis based on the geometric structures behind the solutions leads to an interp ... More
Presented by Mr. Kenta SHIOZAWA on 19 Dec 2018 at 15:00
Session: Short talks
Recently, techniques of Yang-Baxter deformation have been developed to study deformations of string sigma model. The deformation can be regarded as the deformation of the target space, and the deformed background always satisfies the (generalized) supergravity equations of motion. We show that the (homogeneous) YB deformations are a kind of local O(d,d) transformation and discuss its generalizatio ... More
Presented by Dr. Yuho SAKATANI on 18 Dec 2018 at 15:50