Yu Hamada, Kyoto University
Topological Nambu monopole in two Higgs doublet models
Online (Zoom) Two Higgs doublet model (2HDM), in which one more Higgs doublet is added to the Standard Model(SM), is one of the most simple extensions of the SM. 2HDM allows a solitonic object called as the Nambu monopole, which is a magnetic monopole attached with two vortex strings.
Two Higgs doublet model (2HDM), in which one more Higgs doublet is added to the Standard Model(SM), is one of the most simple extensions of the SM. 2HDM allows a solitonic object called as the Nambu monopole, which is a magnetic monopole attached with two vortex strings.
We show that the monopole is topologically stable when the Higgs potential has a global U(1) symmetry and a $¥mathbb{Z}_2$ symmetry. We also discuss phenomenological implications of the monopole. This talk is based on arXiv:1904.09269 and 2003.08772.
Mitsunori Kubota, Osaka University
CP-violating Higgs model canceling the electric dipole moment
Online (Zoom)
5Baryon asymmetry of the Universe requires an extra CP violation and a mechanism for departure from equilibrium for a baryon-number changing process. The extended model with the CP-violating Higgs sector is a good candidate realizing it. However, such extra CP violation is strongly constrained by the electric dipole moment (EDM) data. In this talk, we propose an idea to overcome that conflict between the requirement and the constraint in the general two Higgs doublet model in which the CP-violating phases are originated by the scalar potential and the Yukawa interaction. In our scenario, the contributions to the EDM from the two sources of the CP violation can lead to destructive interference. Consequently, we show that the individual CP-violating phases can get O(1) [rad] while the EDM constraints are satisfied. This talk is based on arXiv:2004.03943 [hep-ph].
Tobias Binder, Kavli IPMU, University of Tokyo
Progress in understanding dark matter Sommerfeld-enhanced annihilation, bound-state formation and decay in the early Universe
Online (Zoom)
If DM is realized at around the TeV-mass region or above, even the heaviest electroweak force carriers could act as long-range forces, leading to the existence of meta-stable DM bound states. The formation and subsequent decay of the latter further deplete the relic density during the freeze-out process on top of the Sommerfeld enhancement, allowing for larger DM masses. In this talk, I discuss how a dense and hot primordial plasma environment influences these quantum mechanical effects, leading to a more complete description and more precise prediction of the thermal WIMP relic abundance.
岡田崇, RIKEN
[cancelled] KEK連携コロキウム「進化ダイナミクスの数理入門」
Tobias Binder, Kavli IPMU, University of Tokyo
[cancelled] Progress in understanding dark matter Sommerfeld-enhanced annihilation, bound-state formation and decay in the early Universe
Seminar room, Kenkyu honkan 3F
If DM is realized at around the TeV-mass region or above, even the heaviest electroweak force carriers could act as long-range forces, leading to the existence of meta-stable DM bound states. The formation and subsequent decay of the latter further deplete the relic density during the freeze-out process on top of the Sommerfeld enhancement, allowing for larger DM masses. In this talk, I discuss how a dense and hot primordial plasma environment influences these quantum mechanical effects, leading to a more complete description and more precise prediction of the thermal WIMP relic abundance.
Reona Arai, Tokyo Institute of Technology
[cancelled] Finite N corrections to the Schur index from D3-brane analysis in AdS_5/CFT_4
Meeting room 1, Kenkyu honkan 1F
We study the AdS/CFT correspondence by using the Schur index, which is the special limit of the superconformal index. Most of this talk, we focus on the correspondence between 4d N=4 U(N) SYM and Type IIB superstring theory on AdS_5×S^5. The agreement of the index at large N limit has confirmed by Kinney et al., but the case of finite N was a long mystery for last decade. In this talk, we propose a calculation method of the index on AdS side for finite N. The key point is to consider D3-branes wrapping three-cycles in S^5. We explicitly calculate contributions of these wrapping D3-branes to the index by analyzing fluctuations on the D3-branes. As far as we checked numerically, our results correctly reproduce the index on CFT side. We also try to apply our method to 4d S-fold theories, which are generalizations of the orientifold theories and have N=3 supersymmetry. Since it is known that S-fold theories have no Lagrangian description, we have to calculate the index on AdS side based on AdS/CFT correspondence. For some special cases, the supersymmetry is enhanced to N=4, and we use this phenomenon as a check for our prediction. You can also see our results are consistent with the supersymmetry enhancement.
Axel Perez-Obiol, Kochi Univ. of Technology
Coulomb 1D problem with general connection condition at the origin and non-Rydberg spectra
Seminar room, Kenkyu honkan 3F
We consider the solution of the quantum Coulomb problem in one dimension with the most general connection condition at the origin. The divergence of the derivative of the wave function at the origin invalidates the standard current conservation approach. We explore two approaches, Wronskian self-adjoint extension method and cutoff regularization method, and establish their mutual relations, thereby clarifying the physical contents of the connection parameters. We show how to realize exotic non-Loudon connection conditions, entailing the realization of non-Rydberg spectrum.
Masafumi Fukuma, Kyoto University
Tempered Lefschetz thimble method: the basics and applications
Seminar room, Kenkyu honkan 3F
The tempered Lefschetz thimble method (TLTM) [arXiv:1703.00861] is a parallel-tempering algorithm towards solving the numerical sign problem. It uses the flow time of the antiholomorphic gradient flow as a tempering parameter, and is expected to tame both the sign and ergodicity problems simultaneously that exist intrinsically in thimble methods. In this talk, we elaborate on the basics of TLTM, and apply the method to various problems, including the (0+1)-dimensional finite-density Thirring model and the quantum Monte Carlo simulation of the Hubbard model away from half filling.
Masafumi Fukuma, Kyoto University
Sign problem in Monte Carlo simulations and the tempered Lefschetz thimble method
Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
When numerically estimating observables on a large-scale system with a complex-valued action, one needs an exponentially long computational time for precise estimation. After reviewing various approaches to this “sign problem”, we explain “the tempered Lefschetz thimble method”, which was introduced by MF and N. Umeda in [arXiv:1703.00861]. We argue that this has a potential to be a universal solution to the sign problem, by explicitly showing that this algorithm gives correct estimates for problems that have been difficult by other algorithms.
Matthew Dodelson, IPMU
High energy behavior of Mellin amplitudes
Seminar room, Kenkyu honkan 3F
