2023年度のセミナー
Date/Place  January 29th (Mon.) 11:0012:00 / H701 

Name  Kohei Kamada (University of Chinese Academy of Science) 
Title  Higgs Inflation in EinsteinCartan Gravity and its UV Extension 
Abstract  The Standard Model Higgs is the unique (possibly) fundamental scalar field we have confirmed its existence thus far. Investigating the possibility if it can drive inflation that explains the present Universe is one of the most important problems in cosmology. Indeed, with a large nonminimal coupling between the Ricci scalar and the Higgs field, the observed cosmological perturbations are generated by Higgs inflation both in metric and Palatini formalisms. Moreover, they are smoothly connected with the help of nonminimal NiehYan term in the EinsteinCartan gravity. However, the relatively small strong coupling scale in these models has been thought to be perhaps problematic, especially at the (p)reheating epoch, and calls for their UV extensions. While the Ricci scalar squared term naturally (from the renormalization of the scalar sector) extends the strong coupling scale to the Planck scale in the metric formalism while it does not in the Palatini formalism. In this talk, I will investigate the renormalization of the Higgs inflation in the EinsteinCartan formalism and show how the Ricci scalar squared term is generally "required" for the renormalization and UVextends the theory. We clarify how it behaves in the Palatini limit where the theory is not UVextended by the Ricci scalar squared term. 
Date/Place  January 23th (Tue.) 15:4016:40 / H701 

Name  Katsuya Hashino (Fukushima Collage) 
Title  Exploring new physics effects through gravitational waves from firstorder phase transition 
Abstract  There are some phenomena that the standard model (SM) cannot explain, such as the baryon asymmetry of the universe, and thus the new physics effects beyond the SM are necessary to explain them. The new effects could potentially act as the cause of firstorder phase transition in the early universe. The production of gravitational waves (GWs) is known to occur if such a firstorder phase transition takes place. The GWs travel through the universe virtually unimpeded, giving us information about the potential of the early universe. In this talk, I will show the possibility of exploring new physics effects through GW observations. 
Date/Place  January 16th (Tue.) 15:4016:40 / H701 

Name  Takahiro Yokokura (Tohoku U.) 
Title  The QCD phase diagram via 't Hooft anomalies 
Abstract  The QCD phase diagram in the space of temperature and imaginary baryon chemical potential has been an interesting subject. However it is difficult to solve QCD analytically because of strong coupling. On the other hand, a notion of an anomaly has been extended in the last decade. In particular an anomaly in the space of coupling constants, which is a generalization of a 't Hooft anomaly, is useful to study a phase diagram because it directly constrains possibilities of the phase diagram. In this talk, I will talk about analysis of the QCD phase diagram by using an anomaly in the space of imaginary chemical potential. First I will explain an anomaly in the space of coupling constants using a free boson on a circle with a theta angle θ. It is important that a phase transition happens in the range of θ=0 to θ=2π. Second I will discuss the anomaly in the space of chemical potential and its implication of the QCD phase diagram. The partition function of QCD has 2π  periodicity of imaginary chemical potential. However the periodicity is broken when we gauge the chiral symmetry of QCD. It is just regarded as the anomaly in the space of coupling constants. This anomaly is analogue to the anomaly in the space of the theta angle of the boson on the circle. Similar to the case of the free boson on the circle, we can constrain the QCD phase diagram. In QCD case, not only a phase transition but also SSB happens in the 2π range of imaginary chemical potential. Finally I will discuss possible degrees of freedom about particular possibilities of phase diagrams. 
Date/Place  January 9th (Tue.) 15:4016:40 / H701 

Name  Nobuhiro Maekawa (Nagoya U.) 
Title  Recent developments on the giantgraviton expansion 
Abstract  After we review the natural GUT which made me convincing twenty years ago that the grand unified theory must be the true theory beyond the standard model, we discuss its problems, which may be hints for the model beyond the GUT. Finally I will introduce a trial to solve one of the problems and discuss the implication for the model beyond the GUT. 
Date/Place  December 22th (Fri.) 13:0014:00 / H701 

Name  Yoshimasa Hidaka (KEK) 
Title  Hamiltonian lattice gauge theory and application to nonequilibrium and dense QCD 
Abstract  I present an approach to lattice QCD using the Hamiltonian formalism for nonequilibrium and finite density. This approach can circumvent the sign problem of QCD that arises from importance sampling. Because the gauge theory has infinitedimensional Hilbert space even on a finite lattice, due to the gauge field being a boson, and because of the large redundancy in degrees of freedom associated with gauge symmetry, it is necessary to introduce regularization to perform calculations. To this end, we employ a qdeformed gauge theory as a regularization technique that preserves the properties of the original gauge theory. As applications of Hamiltonian formalism, I show our results on the thermalization process on a small lattice system, and the thermodynamic behavior at finite density in a (1+1)dimensional system using the density matrix renormalization group technique. 
Date/Place  December 12th (Tue.) 15:4016:40 / H701 

Name  Shota Fujiwara (Witwatersrand U.) 
Title  Recent developments on the giantgraviton expansion 
Abstract  Recently, a new method for calculating the superconformal index, called the giantgraviton expansion, has been established. This method calculates superconformal indices of SCFTs from the holographic dual string theory on AdS spacetime. Specifically, the giantgraviton expansion contains the contribution of wrapped branes (giantgravitons) as a finiteN correction to the largeN indices, and indices of SCFTs of any rank N can be calculated exactly. In this talk we will study recent developments on the giantgraviton expansion and also discuss “the duality” aspect associated to it. 
Date/Place  December 7th (Thu.) 15:00 / H701 

Name  吉村太彦 (東京大学名誉教授) 
Title  「素粒子と宇宙：ある遍歴」(Slides) 
Abstract  素粒子の標準理論は、多くの高エネルギー実験結果で示されたように、ほぼ破綻なく成立していることは間違いない。標準理論を超える唯一のヒントはニュートリノ振動の発見による小さな有限質量であろう。一方、宇宙論からインフレーションと暗黒エネルギーの問題が新たなスカラー場の存在を示唆し、スカラー自由度がどのように標準理論と関係するかが問われている。講演者は、最近、スカラー自由度を含めた新たな重力理論の必要性に注目した理論展開に関わるようになった。ここに至る道筋も含めて素粒子と宇宙のかかわりについてお話したい。 
Date/Place  December 5th (Tue.) 15:4016:40 / H701 

Name  Kei Yamamoto (Hiroshima Institute of Technology) 
Title  Interplay of new physics effects in muon g2, EDM and LFV with U(2) flavor symmetry 
Abstract  The electric and magnetic dipole moments of the electron and the muon are lowenergy probes of New Physics (NP) beyond the Standard Model (SM). The recent experimental measurement of the anomalous magnetic moment of the muon has indicated the discrepancy with the SM prediction. The longstanding muon g2 anomaly might be a hint for new physics. In this seminar, after brief review of U(2) flavor symmetry, I will discuss the interplay of NP among the lepton magnetic moment, the lepton flavor violation (LFV) and the electron electric dipole moment (EDM) in light of recent data of the muon g2, in the SMEFT with the U(2) flavor symmetry. 
Date/Place  November 28th (Tue.) 16:4017:40 / H701 

Name  Tomo Takahashi (Saga U.) 
Title  Mutidimensional perspectives on the Inflationary Universe (Slides) 
Abstract  I discuss the inflationary Universe from "multidimensional" perspectives. In the first part, I consider a multidimensional field space for the inflationary dynamics and discuss the predictions for primordial fluctuations in such a framework, taking the sneutrino inflation model as an example. I discuss how we can construct an inflationary model consistent with current observations even with inflaton potentials which are already excluded in the singlefield framework. In the second part, I talk about a "multidimensional" test of inflation, in which various probes are utilized. Future prospects, including those from the future CMB polarization experiment LiteBIRD in combination with other probes will be given. A possible test with the quantum nature of primordial fluctuations, such as using quantum discord, is also briefly discussed. 
Date/Place  November 21th (Tue.) 15:4016:40 / H701 

Name  Motokazu Abe (Kyusyu U.) (Slides) 
Title  Fractional topological charge in lattice SU(N) gauge theories coupled with Z_N 2form gauge fields 
Abstract  We extend the definition of L\"uscher's lattice topological charge to the case of 4d SU(N) gauge fields coupled with Z_N 2form gauge fields. This result is achieved while maintaining the locality, the $SU(N)$ gauge invariance, and Z_N 1form gauge invariance, and we find that the manifest 1form gauge invariance plays the central role in our construction. This result gives the lattice regularized derivation of the mixed 't~Hooft anomaly in pure $SU(N)$ YangMills theory between its Z_N 1form symmetry and the θ periodicity. 
Date/Place  November 14th (Tue.) 15:4016:40 / H701 

Name  Kimiko Yamashita (Ibaraki U.) 
Title  Positivity Bounds on HiggsPortal Dark Matter 
Abstract  We consider the positivity bounds for WIMP scalar dark matter with effective Higgsportal couplings up to dimension8 operators. Taking the superposed states for Standard Model Higgs and scalar dark matter, we show that the part of the parameter space for the effective couplings, otherwise unconstrained by phenomenological bounds, is ruled out by the positivity bounds on the dimension8 derivative operators. We find that dark matter relic density, direct and indirect detection, and LHC constraints are complementary to the positivity bounds in constraining the effective Higgsportal couplings. We also consider the relic density and positivity bounds for freezein scalar dark matter. 
Date/Place  November 7th (Tue.) 15:4016:40 / H701 

Name  Mohammad Akhond (Kyoto U.) 
Title  5d SCFTs and their nonsupersymmetric cousins 
Abstract  I will argue that combining old ideas such as dualities and exact results in SUSY QFTs supplemented with recent techniques such as SPT phases and generalised anomalies can shed light on strong coupling dynamics of nonSUSY theories. I will in particular show that nonSUSY gauge theories, which are related to SUSY SCFTs by RG in 5d exhibit phase transitions in the UV which are candidates for nonSUSY fixed points. 
Date/Place  October 24th (Tue.) 15:4016:40 / H701 

Name  Akira Matsumoto(YITP) 
Title  Three ways of calculating compositeparticle spectra of gauge theories in the Hamiltonian formalism 
Abstract 
Determination of the mass spectrum of composite particles (hadrons) is one of the key issues in QCD,
which has been precisely calculated by the Monte Carlo simulation based on the Lagrangian formalism.
We newly consider three distinct methods to compute the mass spectrum in the Hamiltonian formalism,
where we can apply quantum computation and tensor network methods.
The first one, the correlationfunction scheme, corresponds to the conventional Euclidean method in the Monte Carlo study.
The second one, the onepointfunction scheme, uses the boundary effect to compute the mass spectrum efficiently.
The third one, the dispersionrelation scheme, generates the excited states to obtain the dispersion relation and quantum numbers.
These methods are demonstrated using the densitymatrix renormalization group (DMRG) in the 2flavor Schwinger model,
which shares important properties with QCD.
We show that their results are consistent with each other, and discuss their potential applications. (preprint: https://arxiv.org/abs/2307.16655) 
Date/Place  October 17th (Tue.) 15:4016:40 / H701 

Name  Emily Nardoni(IPMU) 
Title  Duality of Adjoint SQCD from ArgyresDouglas Theories 
Abstract  The possible conformal fixed points of N=1 adjoint SQCD in four dimensions follow an ADE classification, with some of these SCFTs conjectured to participate in Seiberglike dualities. In this talk, I will discuss a new proposed dual description of some of these fixed points, and provide various consistency checks of the proposal. The duals are built from a class of stronglycoupled N=2 SCFTs of ArgyresDouglas type, coupled to matter and deformed by N=1 preserving deformations. 
Date/Place  October 3rd (Tue.) 15:4016:40 / H701 

Name  Kepan Xie(Beihang U.) 
Title  Matter, dark matter and primordial black holes from firstorder phase transitions 
Abstract  The longstanding puzzles of matterantimatter asymmetry and dark matter point to the need for physics beyond the Standard Model. A firstorder phase transition (FOPT) in the early Universe could provide the necessary conditions for baryogenesis, the generation of dark matter and even primordial black holes. This talk will discuss the basics of cosmic FOPTs and recent developments in relevant new physics mechanisms. 
Date/Place  August 1st (Tue.) 15:4016:40 / H701 

Name  Naoya Kitajima(Tohoku U.) 
Title  Cosmological production of stochastic gravitational waves with ultralow frequencies 
Abstract  In this seminar, I will show the production of stochastic gravitational waves (GWs) in the early universe based on the physics beyond the standard model. I particularly focus on the GWs from (i) parametric resonance instability in the (axionlike) early dark energy model, (ii) decay of axion (ALP) domain walls associated with the QCD phase transition, (iii) network of AbelianHiggs cosmic strings with the emission of light vector boson (dark photon). Those models predict GWs in ultralow frequency bands, namely femtoHz or nanoHz bands, which can be probed by cosmic microwave background observations or pulsar timing observations. We have performed numerical lattice simulations to follow the nonlinear dynamics of scalar field and also to follow the subsequent GW emission process. I will show the resultant GW spectrum in each modeI and also show the implication for the stochastic GW detection recently reported by the NANOGrav Collaboration. 
Date/Place  July 25th (Tue.) 15:4016:40 / H701 

Name  Arata Yamamoto (Tokyo U.) 
Title  Chiral fermion in the Hamiltonian lattice gauge theory 
Abstract  The NielsenNinomiya nogo theorem prohibits the existence of naive chiral symmetry on the lattice. A famous solution to this problem is the overlap fermion. Although the overlap fermion is well established in the path integral formalism, it is not in the Hamiltonian formalism. I will talk about the overlap fermion and its property in the Hamiltonian formalism. I will also show the application to quantum computing. 
Date/Place  July 11th (Tue.) 15:4016:40 / H701 

Name  Tomohiro Abe (Tokyo Univ of Science) 
Title  A pseudoNambuGoldstone dark matter model and direct detection experiments. 
Abstract  Dark matter is one of the mysteries in our Universe. There are so many ideas that explain dark matter. The Weakly Interacting Massive Particle (WIMP) is a popular DM scenario in particle physics. In the WIMP scenario, the DM particles interact with the SM particles, and thus there are various processes. DM annihilation processes are essential to explain the measured value of the energy density of the DM by the freezeout mechanism. The same interaction predicts the creation of the DM particles from the SM particles and motivates the search for DM at collider experiments. The interaction also implies the DMSM scattering processes, which are utilized for DM direct detection. After reviewing WIMP dark matter scenario briefly, I will discuss a pseudoNambuGoldstone DM model that can explain the null results in the recent direct detection experiments. 
Date/Place  July 18th (Tue.) 15:4016:40 / H701 

Name  Thanaporn Sichanugrist (Tokyo U.) 
Title  Detection of hidden photon dark matter using the direct excitation of transmon qubits 
Abstract 
We propose a novel dark matter detection method utilizing the excitation of superconducting transmon qubits. Assuming the hidden photon dark matter of a mass of O(10) µeV, the classical wavematter oscillation induces an effective ac electric field via the small kinetic mixing with the ordinary photon. This serves as a coherent drive field for a qubit when it is resonant, evolving it from the ground state towards the firstexcited state. We evaluate the rate of such evolution and observable excitations in the measurements, as well as the search sensitivity to the hidden photon dark matter. For a selected mass, one can reach ɛ~10^{13}10^{12} (where ɛ is the kinetic mixing parameter of the hidden photon) with a few tens of seconds using a single standard transmon qubit. A simple extension to the frequencytunable SQUIDbased transmon enables the mass scan to cover the range of 440 µeV (110 GHz) within a reasonable length of run time. The scheme has great potential to extend the sensitivity towards various directions including being incorporated into the cavitybased haloscope experiments or the currently available multibit Noisy IntermediateScale Quantum (NISQ) computer machines.
Based on: S. Chen, H. Fukuda, T. Inada, T. Moroi, T. Nitta, T. Sichanugrist, Detection of hidden photon dark matter using the direct excitation of transmon qubits, arXiv: 2212.03884 [hepph] 
Date/Place  July 4th (Tue.) 15:4016:40 / H701 

Name  Masahiro Hotta (Tohoku U.) 
Title  Expanding Edges of Quantum Hall Systems in a Cosmology Language – Hawking Radiation from de Sitter Horizon in Edge Modes 
Abstract  Expanding edge experiments are promising to open new physics windows of quantum Hall systems. In a static edge, the edge excitation, which is described by free fields decoupled with the bulk dynamics, is gapless, and the dynamics preserve conformal symmetry. When the edge expands, such properties need not be preserved. We formulate a quantum field theory in 1+1 dimensional curved spacetimes to analyze the edge dynamics. We propose methods to address the following questions using edge waveforms from the expanding region: Does the conformal symmetry survive? Is the nonlinear interaction of the edge excitations induced by edge expansion? Do the edge excitations interact with the bulk excitations? We additionally show that the expanding edges can be regarded as expanding universe simulators of twodimensional dilatongravity models, including the JackiwTeitelboim gravity model. As an application, we point out that our theoretical setup might simulate emission of analog Hawking radiation with the GibbonsHawking temperature from the future de Sitter horizon formed in the expanding edge region. Recent status of the experiment will be also reported. 
Date/Place  June 30th (Fri.) 16:5017:50 / D401 

Name  Takehiko Asaka (Niigata Univertsity) 
Title  What can we learn from neutrinoless double beta decays in the seesaw mechanism? 
Abstract  Origin of neutrino masses is one of the most important problems in physics today. The scenarios with the seesaw mechanism by introducing righthanded neutrinos is very attractive since it can naturally explain the smallness of neutrino masses observed by experiments. In the seesaw mechanism neutrinos are massive Majorana particles, and the lepton number, which is the accidental symmetry of the Standard Model, is broken, which leads to the nonstandard phenomenon. One important example is the neutrinoless double beta decays. In this seminar, we consider the case when righthanded neutrinos are lighter than TeV scale and show how the properties of righthanded neutrinos (masses, mixing elements etc) can be probed by the neutrinoless double beta decays. 
Date/Place  June 27th (Tue.) 15:4016:40 / H701 

Name  Masazumi Honda (YITP) 
Title  Digital quantum simulation of highercharge Schwinger model with topological term 
Abstract 
I am going to talk about application of quantum computation to numerical simulation of quantum field theory. Specifically we implement a digital quantum simulation of a gauge theory with a topological term in Minkowski spacetime, which is practically inaccessible by standard lattice Monte Carlo simulations.
We focus on 1+1 dimensional quantum electrodynamics with a topological term and a chargeq Dirac fermion known as the Schwinger model.
We construct the true vacuum state of a lattice Schwinger model using adiabatic state preparation which, in turn, allows us to compute an expectation value of the fermion mass operator with respect to the vacuum.
Upon taking a continuum limit we find that our result in massless case agrees with the known exact result.
In massive case, we find an agreement with mass perturbation theory in small mass regime and deviations in large mass regime.
We also study a potential between heavy charged particles and see that the potential changes its qualitative behavior as changing parameters:
it shows confinement, screening and an exotic behavior called negative tension behavior
in which particles with opposite charges repel with each other. Refs:

Date/Place  June 20th (Tue.) 15:4016:40 / H601 

Name  Takato Mori (YITP) 
Title  Causality and entanglement on brane from scattering in the bulk 
Abstract 
In recent years, holography in the presence of branes, especially double holography, has attracted a great deal of attention, e.g. to the black hole evaporation, RandallSundrumlike brane cosmology, and the AdS/BCFT. In double holography, there exists three equivalent pictures. In addition to the usual bulk and boundary perspectives, there is an intermediate perspective where the brane is coupled to a nongravitating bath. However, it has been pointed out that in the presence of such a brane, fundamental properties such as causality and subadditivity are violated. Since the latter is a property that any quantum systems must satisfy, its violation makes the existence of the intermediate picture doubtful.
In this talk, I carefully examine causality of the intermediate picture by considering a particular scattering that requires a connected entanglement wedge. As a result, we show that naive causality undergoes modification and subadditivity is preserved. This talk is based on work in preparation with Beni Yoshida. 
Date/Place  June 13th (Tue.) 15:4016:40 / H701 

Name  Yu Nakayama (YITP) 
Title  Scale vs Conformal 
Abstract  In this talk, I review recent development in the distinction and relation between scale invariance and conformal invariance. I first show the argument for the enhancement from scale invariance to conformal invariance based on the dilaton effective action in two and four dimensions. While the situation in three dimensions is generically open, if I focus on specific theories, I can show the enhancement: an example is the nonlinear sigma model due to Perelman's theorem. If we relax the assumption of the reflection positivity, there are some examples of scaleinvariant but nonconformal interacting field theories. A dipolar magnet, physically realized in nature, is one example. We investigate the nonrenormalization property of the nonconserved current operator in interacting field theories, which is necessary for scale invariance without conformal invariance. 
Date/Place  June 6th (Tue.) 15:4016:40 / H701 

Name  Taiichi Nakanishi (YITP) 
Title  Multipole conserving field theory and the fracton phase 
Abstract  Fractons are quasiparticles with exotic properties; they cannot move alone. These particles are originally studied enthusiastically in the field of quantum information or condensed matter physics, because they show up in spin models with quantum error correcting mechanisms. Recently, fractons have gathered interest from high energy physicists, because the field theories describing fractons have many novel and exotic features which do not found in conventional theories. In this talk, I will explain some spin models with fractonic excitations and some progress in the multipole conserving field theory, that describes fractonic particles. This talk is based on JHEP 03(2023) 188 [arXiv:2212.13006] and an ongoing joint work with Masazumi Honda and Hiromi Ebisu. 
Date/Place  May 30th (Tue.) 15:4016:40 / H701 

Name  Maki Takeuchi (Kobe U.) 
Title  The Mystery of the Standard Model and the ExtraDimensional Model 
Abstract  The Standard Model achieved significant success with the discovery of the Higgs in 2012. However, there are still numerous unexplained phenomena. One of them is the number of generations problem, where quarks and leptons come in three copies with only differences in mass while having identical spin and charge. Is the existence of these three generations a mere coincidence, or is there a deeper reason behind it? The Standard Model cannot explain why there are three generations. On the other hand, the higher dimensional theory offers a possible explanation for the number of generations problem. In the higher dimensional theory, the number of generations is related to the geometry of the extra dimensions. In other words, the number of generations carries a physical meaning associated with the geometry of the extra dimensions. In this seminar, I will talk about the generation structure of the T^2/Z_N orbifold with magnetic flux. 
Date/Place  May 16th (Tue.) 15:4016:40 / H701 

Name  Daichi Takeda (Kyoto U.) 
Title  Spacetimeemergent ring toward tabletop quantum gravity experiments 
Abstract  The AdS/CFT correspondence indicates the existence of quantum materials equivalent to higherdimensional gravity systems, and the discovery of such materials will open up new possibilities for quantum gravity experiments. In this talk, we propose a method to identify ringshaped materials holographically governed by gravitational theories on the pure AdS$_3$ in the lowtemperature phase. When a local source $J$ is applied to such a ring, the response function behaves as if the source effect had propagated on the dual curved spacetime inside the bulk. By optically imaging the response data, we capture the virtual image of $J$ that the gravitational lens creates. Since in the pure AdS$_3$ all null geodesics shot from a boundary point reach the antipodal point, we observe the virtual image only there, which is the signal of the spacetime emergence. We also discuss the experimental parameters and their feasibility. 
Date/Place  May 23th (Tue.) 15:4016:40 / H701 

Name  Juntaro Wada (U. of Tokyo) 
Title  Revisiting AffleckDine Leptogenesis with light sleptons 
Abstract  We revisit the AffleckDine leptogenesis via the LHu flat direction with a light slepton field. Although the light slepton field is favored in lowenergy SUSY phenomenologies, such as the muon g2 anomaly and binoslepton coannihilation, it may cause a problem in the AffleckDine leptogenesis: it may create an unwanted chargebreaking vacuum in the AffleckDine field potential so that the AffleckDine field is trapped during the course of leptogenesis. We investigate the conditions under which such an unwanted vacuum exists and clarify that both thermal and quantum corrections are important for the (temporal) disappearance of the chargebreaking minimum. We also confirm that if the chargebreaking vacuum disappears due to the thermal or quantum correction, the correct baryon asymmetry can be produced while avoiding the cosmological gravitino problem. 
Date/Place  May 9th (Tue.) 15:4016:40 / H701 

Name  Sunil Sake (Osaka U.) 
Title  Sparse RMT and Sparse SYK 
Abstract  SYK model can be thought of as a sparse random matrix, with only a fraction of the full random matrix elements taken to be nonzero. To explore the universality of the properties of the SYK model, we study numerically the properties of the sparse random matrices of the standard ensemble, namely GUE/GOE. We study the behaviour of the system as the randomness is changed, by varying the type and number of coupling constants and the variance of their probability distributions. We analyse various features including the density of states and the Spectral form factor, as well as features tied to chaos like level statistics, Outoftime ordered correlators and operator growth. We also analyze a particular sparse version of SYK model obtained by setting some of the couplings of the SYK model to vanish. 
Date/Place  April 25th (Tue.) 15:4016:40 / H701 

Name  Dongsheng Ge (Osaka U.) 
Title  Boundary induced dynamical phase transition via inhomogeous quenches 
Abstract  Boundary effects play an interesting role in the finitesize physical systems. Those are reminiscent of the choices of the boundary conditions. In this work, we study the boundary induced dynamical properties in the “1+1”dimensional critical systems, driven by the inhomogeneous quenches of SSD and Möbius types. We find that different boundary conditions measured by the boundary entropy lead to different scenarios of phase transitions. We give a holographic interpretation in terms of intersecting branes in AdS3. 
Date/Place  April 18th (Tue.) 15:4016:40 / H701 

Name  Akanksha Bhardwaj (Glasgow U.) 
Title  Graph Neural Network: Its Applications to Constrain BSM Models and EFTs 
Abstract 
Graph Neural Networks have emerged as a powerful tool for operating on graphstructured data, facilitating the exploration of nonEuclidean physics data.
In this talk, I will first discuss an autoencoderbased strategy to facilitate anomaly detection for boosted jets, employing Graph Neural Networks (GNNs).
To overcome the known limitations of GNN autoencoders, we design a symmetric decoder capable of simultaneously reconstructing edge features and node features.
Next, I will discuss the application of GNNs in a supervised scenario where we explore its potential to improve highdimensional effective field theory parameter fits to collider data beyond traditional rectangular cutbased differential distribution analyses. As a specific case, we focus on an SMEFT analysis of pp → top pair production, including top decays, where the linear effective field deformation is parameterized by thirteen independent Wilson coefficients. The application of GNNs allows us to condense the multidimensional phase space information available for the discrimination of BSM effects from the SM expectation by considering all available final state correlations directly. 
Date/Place  April 11th (Tue.) 15:4016:40 / H701 

Name  Nicolo Zenoni (Osaka U.) 
Title  Complexity in (hybrid) de Sitter spacetime 
Abstract 
Holographic volume [1] and action [2,3] complexity are supposed to probe the geometry beyond horizons. For a black hole in antide Sitter (AdS) spacetime, complexity asymptotically increases at a constant rate, as the EinsteinRosen bridge behind the event horizon [5].
In de Sitter (dS) spacetime, instead, complexity manifests a hyperfast growth [6], due to the inflationary expansion of spacetime beyond the cosmological horizon [7]. In this seminar, we consider geometries interpolating between AdS and dS. In particular, we present the time evolution of volume complexity in a class of threedimensional hybrid geometries representing an AdS black hole with a dynamical dS bubble in its interior [8].
We show that, depending on the dynamics of the bubble, complexity behaves qualitatively either as in the AdS black hole or as in the dS case [9].
We then specialize to twodimensional dS in JackiwTeitelboim gravity, and we point out that the dilaton is crucial for complexity to behave as in higher dimension [10]. While volume complexity needs a proper Weyl fieldredefinition to mimicking the higherdimensional result, action complexity naturally meets this expectation.
[1] D. Stanford and L. Susskind, Complexity and Shock Wave Geometries, Phys. Rev. D 90 (2014) 126007 [1406.2678]. [2] A. R. Brown, D. A. Roberts, L. Susskind, B. Swingle and Y. Zhao, Holographic Complexity Equals Bulk Action?, Phys. Rev. Lett. 116 (2016) 191301 [1509.07876]. [3] A. R. Brown, D. A. Roberts, L. Susskind, B. Swingle and Y. Zhao, Complexity, action, and black holes, Phys. Rev. D 93 (2016) 086006 [1512.04993]. [4] L. Susskind, Computational Complexity and Black Hole Horizons, Fortsch. Phys. 64 (2016) 24 [1403.5695]. [5] L. Susskind, Entanglement is not enough, Fortsch. Phys. 64 (2016) 49 [1411.0690]. [6] E. Jørstad, R. C. Myers and S.M. Ruan, Holographic complexity in dS_{d+1}, JHEP 05 (2022) 119 [2202.10684]. [7] L. Susskind, Entanglement and Chaos in De Sitter Space Holography: An SYK Example, JHAP 1 (2021) 1 [2109.14104]. [8] B. Freivogel, V. E. Hubeny, A. Maloney, R. C. Myers, M. Rangamani and S. Shenker, Inflation in AdS/CFT, JHEP 03 (2006) 007 [hepth/0510046]. [9] R. Auzzi, G. Nardelli, G. P. Ungureanu and N. Zenoni, Volume complexity of dS bubbles, 2302.03584. [10] T. Anegawa, N. Iizuka, S. K. Sake and N. Zenoni, Is Action Complexity better for de Sitter space in JackiwTeitelboim gravity?, 2303.05025. 