| Speaker: | Toshifumi Noumi (Kobe Univ.) | |
|---|---|---|
| Title | Gravitational Positivity Bounds and the Standard Model | |
| Abstract | Positivity bounds on low-energy scattering amplitudes provide a criterion for a low-energy effective theory to have a standard UV completion. When applied to gravitational theories, they are expected to imply non-trivial quantum gravity constraints on quantum field theory models, i.e., swampland conditions. In this talk I will introduce recent developments on positivity bounds in gravitational theories and their implications for the Standard Model of particle physics. | |
| E-Print | [1] K. Aoki, T. Quang Loc, T. Noumi, J. Tokuda, [Phys. Rev. Lett. 127, 091602],[arXiv:2104.09682[hep-th]] | |
May | Speaker: | Kohei Fujikura (Kobe Univ.) | |
|---|---|---|
| Title | Baryon Asymmetric Universe from Spontaneous CP violation | |
| Abstract | Spontaneous CP violation, such as the Nelson-Barr (NB) mechanism, is an attractive scenario for addressing the strong CP problem while realizing the observed phase of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. However, not only the CKM phase but also the generation of the baryon asymmetry requires CP violation. We find that the supersymmetric NB mechanism can naturally accommodate the Affleck-Dine baryogenesis within a CP-invariant Lagrangian, and the correct baryon asymmetry can be obtained. We also study radiative corrections to the strong CP phase induced by gauge-mediated supersymmetry breaking and CP-violating heavy fields and show that the strong CP problem is solved in a viable parameter space where the visible sector supersymmetric particles must be lighter than O(100) TeV. Even in the case that they are heavier than the TeV scale, our scenario predicts the neutron electric dipole moment within the reach of the near future experiments. | |
| E-Print | [1] K. Aoki, T. Quang Loc, T. Noumi, J. Tokuda, [Phys. Rev. Lett. 127, 091602],[arXiv:2104.09682[hep-th]] | |
| Speaker: | Nobuchika Okada (Alabama Univ.) | |
|---|---|---|
| Title | Neutrino Mass from Affleck-Dine Leptogenesis and WIMP Dark Matter | |
| Abstract | Affleck-Dine (AD) mechanism for leptogenesis involves the cosmological evolution of a complex scalar field (AD field) that carries a non-zero lepton number. We show how explicit lepton number breaking terms, which involve the AD field needed to implement this scenario combined with fermionic WIMP dark matter, can generate neutrino mass at the one-loop level, thus providing a unified framework for solving four major puzzles of the standard model i.e. inflation, baryogenesis, dark matter, and neutrino mass. We discuss some phenomenological implications of this model. | |
| E-Print | [1] Rabindra N. Mohapatra & Nobuchika Okada, JHEP 03 (2022) 092, [arXiv: 2201.06151 [hep-ph]] | |
| Speaker: | Shigeki Matsumoto (IPMU) | |
|---|---|---|
| Title | Light thermal Dark Matter and the core-cusp problem | |
| Abstract | Thermal dark matter, which is often called the WIMP, is an influential dark matter candidate, as it naturally explains the dark matter density observed today by the freeze-out mechanism. The thermal dark matter, whose mass is lighter than 1GeV, is recently attracting attention, for it may solve the core-cusp problem in our universe. After (briefly) reviewing the dark matter problem, I will discuss one of such light thermal dark matter candidates based on the paper arXiv: 2205.10149. | |
| E-Print | [1] Tobias Binder, Sreemanti Chakraborti, Shigeki Matsumoto, Yu Watanabe, [arXiv:2205.10149 [hep-ph]] | |
June | Speaker: | Kazuhiko Hara (University of Tsukuba, IPAS and TCHoU) | |
|---|---|---|
| Title | High precision measurement of the W boson mass with the CDF II detector | |
| Abstract | CDF Collaboration published a new W-boson mass measurement result of 80,433.5 +- 9.4 MeV, the precision of which exceeds that of all previous measurements combined. This measurement is in significant tension, standing 7σ from the Standard Model expectation. In the seminar, the W mass measurement procedure is over-viewed with highlighting the analysis improvements. A couple of theoretical papers relating to this new value are briefly introduced. | |
| E-Print | [1] Taiga Harada, Yu Nakayama, [arXiv:2203.07587 [hep-th]] | |
| Speaker: | Takaaki Nomura (Sichuan university) | |
|---|---|---|
| Title | Neutrino mass models with modular flavor symmetry | |
| Abstract | In this talk we will discuss neutrino mass models in which modular flavor symmetry is applied. Firstly I will review neutrino mass models showing some examples with modular flavor symmetry. We then discuss a model in which neutrino mass is generated at one loop level where a diagram with supersymmeric partner also play an important role in realizing realistic neutrino mass matrix. I will show some predictions in neutrino sector obtained from the model. | |
| E-Print | [1] Takaaki Nomura, Hiroshi Okada [arXiv:2201.10244 [hep-ph]] | |
| Journal Club | ||
|---|---|---|
| Speaker: | Shota Kikuchi (Hokkaido university) | |
| Title | Modular Flavour Symmetries and Modulus Stabilisation | |
| E-Print | [1] P. P. Novichkov, J. T. Penedo and S. T. Petcov, doi:10.1007/JHEP03(2022)149 [arXiv:2201.02020 [hep-ph]] [2] P. P. Novichkov, J. T. Penedo and S. T. Petcov, Nucl. Phys. B 963 (2021), 115301 doi:10.1016/j.nuclphysb.2020.115301 [arXiv:2006.03058 [hep-ph]] [3] P. P. Novichkov, J. T. Penedo and S. T. Petcov, doi:10.1007/JHEP04(2021)206 [arXiv:2102.07488 [hep-ph]].JHEP 04 (2021),206 [4] E. Gonzalo, L. E. Ibáñez and Á. M. Uranga, doi:10.1007/JHEP05(2019)105 [arXiv:1812.06520 [hep-th]].JHEP 03 (2022), JHEP05(2019),149105 | |
July | Speaker: | Kazuhiro Tobe (Nagoya KMI Univ.) | |
|---|---|---|
| Title | Phenomenology of S_1 scalar leptoquark motivated by the muon g-2 anomaly | |
| Abstract | Although a Higgs boson was discovered, the nature of the Higgs boson, the structure of the Higgs sector, the dynamics of the electroweak symmetry breaking are still A discrepancy between the standard model (SM) prediction and the experimental value of muon anomalous magnetic moment (muon g-2) has been reported. If this is due to the new physics contributions, it can be a very good hint for the new physics. Since the size of the discrepancy is almost the same as the one of the electroweak contribution in the SM, we naively expect that the mass scale of new physics is close to the electroweak scale. However, the new physics close to the electroweak scale is now strongly constrained by the direct search experiment at the LHC. In this talk, we consider the S_1 leptoquark (LQ) scenario where the LQ contribution to the muon g-2 has a large enhancement so that the TeV scale LQ can still give a sizable correction to the muon g-2, while it can escape from the LHC constraint. In the S_1 LQ scenario, we study processes such as "b→c τ ν” and ”b → s μ+ μ-" where discrepancies between the SM predictions and the experimental results have been reported as well, and we show how large deviations from the SM predictions are possible and whether the S_1 LQ can accommodate some of the discrepancies simultaneously. | |
| Speaker: | Ryosuke Sato (Osaka Univ.) | |
|---|---|---|
| Title | Muon electric dipole moment as a probe of flavor-diagonal CP violation | |
| Abstract | The muon g-2 anomaly motivates us to explore a possibility of muon electric dipole moment (EDM) since both g-2 and EDM get contributions from dipole operators. In this talk, I discuss two Higgs doublet model as an example of such an scenario. This model can be probed by muon EDM experiments such as PSI and J-PARC. | |
| E-Print | [1] Y. Nakai, R. Sato, Y. Shigekami, https://doi.org/10.1016/j.physletb.2022.137194., [arXiv: 2204.03183 [hep-ph]] | |
| Speaker: | Hiroshi Kunitomo (YITP) | |
|---|---|---|
| Title | Open-closed homotopy algebra in superstring field theory | |
| Abstract | We construct open-closed superstring interactions based on the open-closed homotopy algebra structure. It provides a classical open superstring field theory on general closed-superstring field backgrounds described by classical solutions of the nonlinear equations of motion of the closed superstring field theory. | |
| E-Print | [1] Hiroshi Kunitomo, [arXiv: 2204.01249 [hep-th]] | |
| M2 mid term presentation | ||
|---|---|---|
| Speaker: | Ibuki Yamamoto | |
| Title | Robin boundary condition for massive string | |
| M2 mid term presentation | ||
|---|---|---|
| Speaker: | Shohei Takada | |
| Title | Classifications of zero-modes on magnetized orbifold models | |
| Speaker: | Yuji Takai | |
| Title | Generalizing theorems to 2-dimensional surface | |
October | Journal Club | ||
|---|---|---|
| Speaker: | Yuta Mimura (Hokkaido Univ.) | |
| Title | TBA | |
| Journal Club | ||
|---|---|---|
| Speaker: | Cristopher Chune (Hokkaido Univ.) | |
| Title | A Ricci flow approach to very early universe | |
| E-Print | [1] M.J.Luo, [arXiv:2112.00218 [gr-qc]] | |
| Journal Club | ||
|---|---|---|
| Speaker: | Ryo Tomisawa (Hokkaido Univ.) | |
| Title | U(1) gauge theory and Yang-Mills theory | |
November | Journal Club | ||
|---|---|---|
| Speaker: | Takayoshi Shirai (Hokkaido Univ.) | |
| Title | Extension of general relativity for accelerating expansion of universe | |
| Speaker: | Kento Akamatsu (Osaka Metropolitan University) (Main speaker), Takuya Hirose (Osaka Metropolitan University) | |
|---|---|---|
| Title | Gauge Symmetry Breaking in Flux Compactification with Wilson-line Scalar Condensate | |
| Abstract | We discuss the gauge symmetry breaking of six dimensional theories in flux compactification with a magnetic flux background and a constant vacuum expectation value (VEV) for the scalar fields, which are zero modes of extra spatial components of the gauge field. Although the effective potential for the scalar fields are known not to be generated classically and radiatively in a magnetic flux background only, the one-loop effective potential is shown to be generated by the effects of the nonzero constant VEV. As illustrations, we calculate the one-loop effective potential in SU(2) and SU(3) Yang-Mills theories. In both cases, we find that the potential minimum is located at non-zero VEV and the gauge symmetry breaking takes place. In the seminar, I will start from a review of the ordinary flux compactification. After that, I will show you our work, the theory with a magnetic flux background and a constant VEV. Finally, I will share our work in progress and some problems. | |
| E-Print | [1] Kento Akamatsu, Takuya Hirose, Nobuhito Maru [arXiv: 2205.09320 [hep-th]] | |
| Speaker: | Josh Kirklin (OIST) | |
|---|---|---|
| Title | Emergent classical gauge symmetry from quantum entanglement | |
| Abstract | I will describe explicitly how entanglement between quantum mechanical subsystems can lead to emergent gauge symmetry in a classical limit. First, I will provide a precise characterisation of when it is consistent to treat a quantum subsystem classically in such a limit. I will show that this gives strong constraints on the entanglement structure of classical states, leading to fundamentally non-local classical degrees of freedom which may be accounted for using an emergent gauge symmetry. For concreteness I will exhibit a toy example involving three entangled spins at high angular momentum, and a significant group-theoretic generalisation of this toy example. If there is time, I will discuss evidence that this phenomenon plays a role in the emergence of bulk diffeomorphism invariance in gravity. | |
| E-Print | [1] Josh Kirklin [arXiv:2209.03979 [hep-th]] | |
| Seminar | ||
|---|---|---|
| Speaker: | Nicholas J. Benoit | |
| Title | Effects of renormalization group kernels on the lightest neutrino mass in the Type-I Seesaw model | |
| Abstract | The Type-I seesaw model is a common extension to the Standard Model that describes neutrino masses. The Type-I seesaw introduces heavy right-handed neutrinos with Majorana mass that transform as Standard Model electroweak gauge singlets. We initially study a case with two right-handed neutrinos called the 3-2 model. At an energy scale above the right-handed neutrinos, the effective neutrino mass matrix is rank degenerate, implying the lightest neutrino is massless. After considering renormalization effects below the two right-handed neutrinos, the effective neutrino mass matrix remains rank degenerate. Next, we study a model with three right-handed neutrinos called the 3-3 model. Above the energy scale of the three right-handed neutrinos, we construct the effective neutrino mass matrix to be rank degenerate. After solving for the renormalization effects to energies below the three right-handed neutrinos, we find the rank of the effective neutrino mass matrix depends on the kernel solutions of the renormalization group equations. We prove, for the simplest kernel solutions, the effective neutrino mass matrix remains rank degenerate. | |
| E-Print | [1] Nicholas J. Benoit, Takuya Morozumi, Yusuke Shimizu, Kenta Takagi, Akihiro Yuu [arXiv:2210.00165 [hep-ph]] | |
| Journal Club | ||
| Speaker: | Toshiki Kawai (Hokkaido Univ.) | |
| Title | Self-tuning mechanism of the cosmological constant in a brane-world scenario | |
December | Speaker: | Teppei Kitahara (KMI) | |
|---|---|---|
| Title | Hunting for new physics in precision measurements of flavor physics | |
| Abstract | Precise measurement of elementary particles is one of the powerful methods to search for new physics beyond the Standard Model. It provides a comparable and complementary sensitivity to direct searches at the LHC. Precise measurements of flavor physics, particularly meson decays, are essential for investigating new physics. Several meson decays give theoretically clean and/or experimentally clean observables which lead to excellent sensitivity. In recent years, a number of experimental anomalies have been found by these precision measurements. Struggling to explain the anomalies in new physics is a task of particle phenomenology, and the Standard Model itself also has such a history. In this talk, I will present recent progress with new physics interpretations of the flavor anomalies known as lepton flavor universality violation, includes the recent results of our collaborations [1,2]. I will also argue the current situations of the muon g-2 anomaly and W boson mass anomaly. | |
| E-Print | [1] Syuhei Iguro, Teppei Kitahara, Ryoutaro Watanabe [arXiv:2210.10751 [hep-ph]] [2] Marco Fedele, Monika Blanke, Andreas Crivellin, Syuhei Iguro, Teppei Kitahara, Ulrich Nierste, Ryoutaro Watanabe [arXiv:2211.14172 [hep-ph]] | |
| Speaker: | Noboru Kawamoto (Hokkaido Univ.) | |
|---|---|---|
| Title | Sapporo-Torino collaboration for lattice supersymmetry | |
| Seminar | ||
|---|---|---|
| Speaker: | Kai Murai (ICRR & IPMU) | |
| Title | Isotropic cosmic birefringence from early dark energy | |
| Abstract | The Type-I seesaw model is a common extension to the Standard Model that describes neutrino masses. The Type-I seesaw introduces heavy right-handed neutrinos with Majorana mass that transform as Standard Model electroweak gauge singlets. We initially study a case with two right-handed neutrinos called the 3-2 model. At an energy scale above the right-handed neutrinos, the effective neutrino mass matrix is rank degenerate, implying the lightest neutrino is massless. After considering renormalization effects below the two right-handed neutrinos, the effective neutrino mass matrix remains rank degenerate. Next, we study a model with three right-handed neutrinos called the 3-3 model. Above the energy scale of the three right-handed neutrinos, we construct the effective neutrino mass matrix to be rank degenerate. After solving for the renormalization effects to energies below the three right-handed neutrinos, we find the rank of the effective neutrino mass matrix depends on the kernel solutions of the renormalization group equations. We prove, for the simplest kernel solutions, the effective neutrino mass matrix remains rank degenerate. | |
| E-Print | [1] Kai Murai, Fumihiro Naokawa, Toshiya Namikawa, Eiichiro Komatsu [arXiv:2209.07804 [astro-ph.CO]] | |
| Journal Club | ||
| Speaker: | Yoshihiro Aiko(Hokkaido Univ.) | |
| Title | The Black Hole Information Problem and Possible Resolutions | |
| Journal Club | ||
|---|---|---|
| Speaker: | Riku Sakuma (Hokkaido Univ.) | |
| Title | Standard Model of Particle Physics | |
January | Rehearsal for Master Thesis presentation | ||
|---|---|---|
| Speaker: | Ibuki Yamamoto (Hokkaido Univ.) | |
| Title | Motion of string connected to D-brane with finite mass. | |
| Abstract | D-brane is multidimensional object that has never moved. In other word, it means D-brane has infinity mass. So, In this master's thesis, I research the motion of D0-brane with finite mass and motion of string that connects to it. Different from string theory, I found that finite mass D-brane has log divergence. | |
| Journal Club | ||
| Speaker: | Motoya Harada (Hokkaido Univ.) | |
| Title | Transforming singular black holes into regular black holes sourced by nonlinear electrodynamics | |
| Rehearsal for Master Thesis presentation | ||
|---|---|---|
| Speaker: | Shohei Takada (Hokkaido Univ.) | |
| Title | Zero modes on magnetized non-factorizable T6/ZN model | |
| Abstract | We study zero-modes on magnetized T6/ZN model. In particular, we focus on the case of non-factorizable orbifolds, or N=7, 12. I will introduce a way of classifications of zero-modes on such orbifolds. | |
| Rehearsal for Master Thesis presentation | ||
|---|---|---|
| Speaker: | Yuji Takai(Hokkaido Univ.) | |
| Title | Extensions of theorems about classical particles to theorems about classical strings in Lorentzian manifold | |
| Abstract | I studied classical strings in a general Lorentzian manifold. I found that it is possible to extend some theorems about classical particle to theorems about classical string. | |
| Seminar | ||
| Speaker: | Eung Jin Chun (KIAS) | |
| Title | Particle dispersion in the classical vector dark matter background | |
| Abstract | Interactions with a background medium modify in general the dispersion relation and canonical normalization of propagating particles. This can have an important phenomenological consequence when considering light dark matter coupling to quarks and leptons. In this paper, we address this issue in the vector dark matter background with the randomly distributed polarizations or a fixed polarization to the single direction. The observations associated with particle dispersion can give constraints on new light Abelian gauge boson models. Considering the solar neutrino transition and the electron mass measurement, stringent bounds can be put on the gauged. Lμ−Lτ model and the dark photon model. Moreover, the classical vector field turns out to induce drastic changes in the particle normalization, which rule out a significant parameter region of the generic vector dark matter model. | |