Kyohei Mukaida, DESY
Baryogenesis from Axion Inflation
Online (Zoom) https://kds.kek.jp/indico/event/34874/
In inflation models driven by an axion-like particle, the inflaton may have a Chern-Simons coupling to the Standard Model (SM) U(1)_Y. In this talk, we show that this setup is a highly predictive baryogenesis model without further ingredients other than the SM and the inflaton. During inflation, this Chern-Simons coupling sources a dual production of the SM chiral fermions and maximally helical U(1)_Y gauge fields, associated with the SM chiral anomaly equation. The anomalous transport of these primordial chiral asymmetries and the helical U(1)_Y gauge fields after inflation gives rise to the present baryon asymmetry. The observed baryon asymmetry can be reproduced if the Hubble parameter of inflation is around Hinf ~ 10^10 – 10^12 GeV with moderate dependence on inflation model parameters.
木村裕介, KEK
理論センタープロジェクト「弦からヒッグズ／フレーバー」セミナー 1/2 Calabi-Yau 4-folds and 4D F-theory on the double covers
Online (Zoom)
詳しくはプロジェクトのページhttps://www2.kek.jp/theory-center/project/string2higgsflavor/2020/06/15/projectseminar_halfcy/をご覧ください。
Shigenori Seki, Doshisha
Formulation and Evaluation of Entanglement Entropy in Elastic Scattering
Online (Zoom) https://kds.kek.jp/indico/event/34653/
We are interested in the entanglement entropy of the final state of two particles in an elastic scattering. By using the partial wave expansion of two-particle states within an S-matrix theory, we obtain the formula that expresses the entanglement entropy of the final state in terms of physical observables. Then, following this formula, we evaluate quantitatively the entanglement entropy in proton-proton scatterings at collider energies.
Meng-Ru Wu, Academia Sinica
[KEK-Keio-YITP Joint seminar] Supernova explosion of massive stars driven by hadron-quark phase transition and its signature
Online (Zoom)
The physical mechanism(s) accounting for supernova explosion of massive stars has not been verified by observations. A potential phase-transition from hadronic matter to quark matter at high density during the collapse of a stellar core has been proposed as a possible way to trigger an explosion. In this talk, I will discuss results of Fischer+ 1712.08788 & 2003.00972 in which this scenario was revisited with simulations adopting equations of state which contain such a transition while being compatible with known nuclear and astrophysical constraints. We found that for a star with a progenitor mass of ~ 35 to 50 solar masses, a successful explosion can be obtained by the strong second shockwave resulting from the collapse of the proto-neutron star due to the phase transition. Moreover, such an explosion can lead to a number of interesting consequences, including the formation of a remnant neutron star as heavy as ~ 2 solar mass, the release of a millisecond neutrino burst signal, the potential range of the supernova lightcurve, and the production of r-process nuclei.
Tomonori Ugajin, YITP
Entanglement between two disjoint universes
Online (Zoom) https://kds.kek.jp/indico/event/34847/ We study island phenomena of a thermo field like entangled state on two disjoint universes when gravity is turned only on one of them.
We study island phenomena of a thermo field like entangled state on two disjoint universes when gravity is turned only on one of them.
We show even in this case the entanglement entropy between two universes is computed by a generalized entropy, of the region on the gravitating universe which minimizes the function. The entanglement between two universes creates a causal shadow region in the black hole in the gravitating universe, which is identified with the island in this set up in the high temperature limit. We also confirm when the entanglement temperature is larger than the temperature of the black hole, the entanglement entropy between two universe coincides with the black hole entropy, a kind of Page behavior.The growth of the causal shadow region in the black hole interior has a natural interpretation in the holographic dual of this setup. The holographic setup involves one dimensional higher eternal black hole, whose boundaries naturally realize two universes. Since the causal shadow defines an interval on one of the boundaries, its growth means the growth of the entanglement wedge of the non gravitating universe, which leads to the complete bulk reconstruction from the non gravitating boundary.
Yuta Hamada, Laboratoire AstroParticule et Cosmologie
Brane gaugino condensate and 10d description of 4d de Sitter vacua
Online (Zoom) https://kds.kek.jp/indico/event/34805/
We analyze the structure of gaugino interactions on D7-branes from a 10d perspective. This is essential if one wants to lift the standard 4d approach to type IIB moduli stabilization in 10d. Motivated by the structure of heterotic and Horava-Witten theories, we suggest an extension of the brane action by a particular four gaugino operator. In a simple toroidal compactification, we demonstrate that the 4d effective potential is exactly reproduced from 10d.
Yuya Tanizaki, YITP, Kyoto University
Modifying instanton sums in QCD
Online (Zoom), indico page, slides (kek.jp only)
In the path integral formulation, we need to sum up all possible field configurations to define a QFT. If the configuration space is disconnected, we must specify how they should be summed by giving extra data to specify the QFT. In this talk, we try to restrict the possible number of instantons in SU(N) gauge theories, Yang-Mills theory and QCD, and we find out the vacuum structures of them. For consistency with locality, we have to introduce an extra topological degrees of freedom, and the theory acquires the 3-form symmetry. The existence of this 3-form symmetry leads to extra vacua/universes, and moreover it turns out to give a stronger version of superselection rule for the domain-wall excitation/vacuum decay.
Kazunori Kohri, KEK
[cosmophys seminar] Photodissociation of light elements with sub-GeV massive decaying particles
Online (Zoom)
We consider the effects of the injections of energetic photon and electron (or positron) on the big-bang nucleosynthesis. We study the photodissociation of light elements in the early Universe those injections paying particular attention to the case that the injection energy is sub-GeV and derive upper bounds on the primordial abundances of the massive decaying particle as a function of its lifetime. We pay particular attention to the case that the injection energy is sub-GeV. We also discuss a solution of the Li7 problem in this framework.
Yutaka Ookouchi, Kyushu University
Catalytic Creation of Baby Bubble Universe with Small Positive Cosmological Constant
Online (Zoom), indico page, slides (kek.jp only)
In this talk, I will discuss the decay of metastable de Sitter vacua catalyzed by a black hole and a cloud of strings and apply the method to the creation of the four dimensional bubble universe in the five dimensional AdS spacetime. We study the bounce action for the creation and find that the bubble with very small cosmological constant is favored by the catalysis by assuming appropriate mass scales of the black hole and the cloud of strings to reproduce the present energy densities of matter and radiation in the bubble universe.
Jian-Hua Gao, Shandong University, China
[KEK-Keio-YITP joint seminar] The second order anomalous currents from Wigner function approach
Online (Zoom)
