Contribution List

Abstract:

The interaction can be obtained by imposing gauge symmetry on the Lagrangian, and the S-matrix can be calculated using the Feynman rule. In Quantum ElectroDynamics (QED), the diagram has divergences at higher-order. We introduce the “renormalization" to solve this problem. I will talk about the energy dependence of the renormalized coupling constant.

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In this talk, we will look at the history of particle physics and look at the Standard Model. The gauge principle and Higgs mechanism, which form the basis of the Standard Model, will be briefly explained. Phenomena that cannot be explained by the Standard Model will also be introduced, and baryogenesis will be presented as physics beyond the Standard Model.

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I will talk about the problems in the SM and introduce BSM theory to solve these problems. The BSM theory I will talk about is a higher dimensional theory with extra dimensions. From the viewpoint of solving the hierarchy problem of Higgs mass, I will introduce a model of gauge-Higgs unification in 5-dimensional space-time, that considers the Higgs field as a gauge field rather than a scalar field. This talk will be for those who know the Standard Model.

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General relativity has been accepted as the most successful theory of gravity for the past century and underpins the foundations of modern cosmology. On the other hand, today, observations of the universe confirm behavior that cannot be understood by existing physical theories. There has been an attempt to explain this by modifying the theory of gravity within the category of classical physics, which is called the modified theory of gravity, and significant progress has been made, especially in the last 20 years. In this talk, I will give an introduction to general relativity, which is the basis of cosmology, and then briefly introduce a very clear theory among the modified theories of gravity and how to verify the theory.

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Abstract:

In my talk, I will discuss two things. First is Big Bang cosmology. Big Bang cosmology is the theory which claims the universe has expanded from the initial state of high temperature and density. This theory is successful in describing many phenomena that occurred in the universe, such as Big Bang nucleosynthesis and Cosmic Microwave Background. I will talk about how these phenomena can be explained by Big Bang cosmology.

　The second is inflation. Inflation is a rapidly accelerated expansion of space before the Big Bang and is introduced to solve problems that cannot be explained only by Big Bang cosmology. : Horizon problem and Flatness problem. To realize inflation, we have to consider unusual matter whose density is constant even though space expands. In my presentation, I will talk about how these two problems are avoided by inflation and introduce "slow-roll inflation" which is one example to realize it.

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Abstract:

The resent research by James Webb Space Telescope (JWST) found massive galaxy candidates with 7<z<10. These star formation efficiencies has a tension with ΛCDM model, the standard cosmological model. I will talk about what is the tension between the JWST observation and ΛCDM model and how to ease it.

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Abstract:

In the local Universe, the morphological properties of galaxies are mainly divided into two (or three) groups, which is called the Hubble sequence. One is ʻʼspiral galaxiesʼʼ which is like the Milky Way morphology, and the other is ʻʼelliptical galaxiesʼʼ which has no spiral arms. Under normal circumstances, galaxies produce stars from gas material. However, massive elliptical galaxies display a lack of star-forming activity and are primarily composed of old stars. ʻʼWhy did these galaxies stop their star formation?ʼʼ This is one of the important questions in the galaxy formation and evolution field. To solve this problem, we conduct the observation of the galaxies that stop star formation at high redshift and try to confirm the physical mechanism of quenching (suppressing their star formation) directly. In this presentation, I will explore the formation scenario of a quiescent galaxy in the early universe that I have uncovered. Additionally, I will provide an overview of the observational astronomy techniques we employ, including methodologies and data acquisition.

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Abstract:

Stars are the fundamental units of astronomical objects. The systematic properties of stars, their time evolution, and their lifetimes provide us with fundamental information for considering the evolution of galaxies and the universe. From the viewpoint of particle nuclear physics, stars are also test sites for nuclear reactions such as hydrogen fusion reactions. The white dwarf, neutron stars and black holes that formed at the centar of the star are still the subject of interest in astronomy, astrophysics, and particle nuclear physics. My talk will introduce the fundamentals of stellar physics, which will be important in a wide range of research fields. I hope this will spark your interest in stellar physics.

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In 2015, 100 years after Einstein proposed general relativity in 1915, the first direct observation of gravitational waves generated by binary black hole mergers was predicted. This represents the birth of a new physics and is greatly expected to contribute to the multi-messenger astronomy. However, it can be said that the theory has not yet caught up with the development of the theory. In this talk, the main focus will be given to providing a basic knowledge of what gravitational waves are. Finally, gravitational wave echoes will be introduced as a potential bridge to quantum gravity theory.

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Abstract:

Since the Chern-Simons term in compactified higher-dimensional gauge theories is derived from the Wilson-Loop phase obtained from the line integral of the extra-dimensional component (𝐴𝑦) of the gauge field, the CS term should be periodic in 𝐴𝑦. In this paper, we derive the CS term as a periodic function of 𝐴𝑦 in higher dimensional theory and point out the appropriate CS term. It then approaches the solution of the CP problem under higher dimensional theory and a CS term periodic in 𝐴𝑦.

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Abstract:

In higher-dimensional gauge theories with compact spaces, there are numerous choices for boundary conditions. Some of them can be connected through gauge transformations and constitute equivalence classes, each of which contains physically equivalent boundary conditions. In previous studies, equivalence classes have been classified through specific gauge transformations. In our work, we have achieved a general classification of equivalence classes independent of the structure of gauge transformations, using only the geometric properties of boundary conditions, for SU(N) gauge theories on S^1^/Z_2 or T^2^/Z_3. We will talk about these results.

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Abstract:

Electroweak symmetry breaking is explored in a two Higgs doublet model based on a six dimensional SU(4) gauge-Higgs unification. The remarkable property of this model is a prediction of realistic weak mixing angle at the compactification scale. We calculate one-loop effective potential of the Standard Model Higgs boson from the contributions of the gauge boson and the fermion in a four-rank totally symmetric tensor where top quark is included. We find that the electroweak symmetry breaking certainly takes place.

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Six dimensional gauge theories compactified on a magnetized orbifold are considered, where the generation number of fermions can be understood as the degree of degeneracy of fermion zero modes. We investigate whether three-generation models compatible with Yukawa couplings are possible and find such various models except for two Higgs doublet model in T^2/Z_2 flux compactification. This talk is based on arXiv:2311.10324.

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Abstract:

We investigate gauge theories on a twelve-dimensional spacetime with an eight-dimensional coset space as an extra space. The scheme of coset space dimensional reduction is employed to obtain four-dimensional theories and to analyze their particle contents. Then we found that some SO(18) models in twelve dimensions leads to SO(10) GUT-like models in four dimensions, where the fermions in the Standard Model appear in multiple generations along with scalars that may break the electroweak symmetry. The representations of the obtained scalars and fermions are summarized.

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Abstract:

We know two unifications, grand unification and gauge-Higgs unification. There is an attempt to discuss grand unification in the scenario of gauge -Higgs unification, say "grand gauge-Higgs unification". In my talk, I want to show 5D SU(6) grand gauge-Higgs unified model and try to extend it to unify family too.

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Abstract:

We propose an SU(5) GUT model extended with two additional pairs of 10 representation vector-like fermions. The CDF collaboration W boson mass anomaly is explained by using the VEV of a real SU(2)L triplet scalar coming from the 24 representation Higgs. The vector-like fermions are decomposed partly into vector-like quark doublets. Those vector-like quark doublets acquire mass from two sources; through the Yukawa interaction with the real SU(2)L triplet via a type-Ⅱ seesaw-like mechanism. And, they acquire mass from the 24 representation Higgs. We assume that the mass for the vector-like quark doublets is expressed in terms of the real triplets mass. By combining the constraints on the vector-like quark masses with those on the heavy Higgs boson masses, we can obtain the narrow allowed mass ranges for the vector-like quark doublet and the real triplet. Therefore, our model can be tested in searches for these particles in the near future. In addition, the two additional pairs of vector-like fermions allow the SM gauge couplings to unify successfully at MGUT ≈5.1×10^15 GeV. Our model is also testable by the future Hyper-Kamiokande experiment via the proton decay lifetime τ_p (p⟶π^0 e^+)<1.0×10^35 years.

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Abstract:

The standard model(SM) fermions, quarks and leptons, have a generation structure. That means there are mass hierarchy and flavor mixing. The SM only assigns parameters to generation structure and does not provide a theoretical explanation. In this study, we build new flavor model with the S4 symmetry. 

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Abstract:

We propose a method to explore the flavor structure of quarks and leptons with reinforcement learning, which is a type of machine learning. As a concrete model, we focus on the Froggatt-Nielsen model with U(1) flavor symmetry. By training neural networks on the U(1) charges of quarks and leptons, the agent finds appropriate models to be consistent with experimentally measured masses and mixing angles of quarks and leptons. In particular, The normal ordering of neutrino masses is well fitted with the current experimental data in contrast to the inverted ordering. Moreover, a specific value of effective mass for the neutrinoless double beta decay and a sizable leptonic CP violation. Our finding results indicate that the reinforcement learning can be a new method for understanding the flavor structure. The reference is arXiv:2304.14176 [hep-ph].

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Abstract:

Anomalous high energy photons, known as GRB221009A, with 18 TeV and 251 TeV were observed by LHAASO and Carpet-2 recently. Such observation of high energy gamma-ray bursts from distant source causes a mystery since high energy photons suffer severe attenuation before reaching at the earth. One possibility is the existence of axion-like particles (ALP), and high energy photons at the source can convert to these ALPs which travel intergalactically. In this paper, authors study the effects of extra dimensions on the conversion probability between photon and ALPs. The conversion probability saturates and may reach almost 100% for high energy photons. It is shown that the size of extra dimension affects the energy at which saturation occurs. The observations of high-energy photons may support the possibility of smaller extra dimension.

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Abstract:

Dark matter (DM), which is still unidentified and proposed by astronomical observations, is one of the motivations for extending the Standard Model. In the model that introduces a complex singlet scalar field into the Standard Model (Complex singlet extension of the SM; CxSM), the imaginary part of the complex scalar field behaves as a dark matter candidate particle. If the scattering of DM and nucleons is sufficiently suppressed when the masses of scalar mediators are degenerate, it is possible to construct a dark matter model that is consistent with observations that strongly limit the dark matter-nucleon scattering cross section of direct detection experiments. On the other hand, the scalar DM included in the model gives only a tiny amount of the relic density as compared to the observed one, so new DM candidate particles are needed. In this study, we show that simultaneously satisfy the observed relic density by introducing new fermion DM candidate into the CxSM and discuss phenomenology with the new model.

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Abstract:

I will give a general discussion about colliders and introduce the current status of muon colliders. Future colliders are expected to discover new particles and interactions at TeV-scale and to survey the Standard Model particles precisely. Muon collider is one of the most attractive options in the sense that it is the center of particle physics and a challenging study.

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