Takahiko Matsubara, KEK
[Cosmophys seminar] Weakly non-Gaussian formula for Minkowski functionals in general dimensions
Online (Zoom) The Minkowski functionals are useful statistics to quantify the morphology of various random fields. They have been applied to a large number of analyses of geometrical patterns, including various types of cosmic fields, morphological image processing, etc. In some cases, including cosmological applications in particular, small deviations from Gaussianity of distribution have a fundamental importance. Analytic formulas of expectation values of Minkowski functionals with small non-Gaussianity have been derived in limited cases so far. We generalize the previous work to derive an analytic expression for expectation values of Minkowski functionals up to second-order corrections of non-Gaussianity in a space of general dimensions. The derived formula has sufficient generality to be applied to any random fields with weak non-Gaussianity in a statistically homogeneous and isotropic space of any dimensions.
The Minkowski functionals are useful statistics to quantify the morphology of various random fields. They have been applied to a large number of analyses of geometrical patterns, including various types of cosmic fields, morphological image processing, etc. In some cases, including cosmological applications in particular, small deviations from Gaussianity of distribution have a fundamental importance. Analytic formulas of expectation values of Minkowski functionals with small non-Gaussianity have been derived in limited cases so far. We generalize the previous work to derive an analytic expression for expectation values of Minkowski functionals up to second-order corrections of non-Gaussianity in a space of general dimensions. The derived formula has sufficient generality to be applied to any random fields with weak non-Gaussianity in a statistically homogeneous and isotropic space of any dimensions.
This talk is based on a paper in preparation with Satoshi Kuriki (ISM).
Riki Toshio, Kyoto University
[QCD theory seminar] Anomalous Hydrodynamic Transport in Interacting Noncentrosymmetric Metals
Online (Zoom) In highly conductive metals with sufficiently strong momentum-conserving scattering, the electron momentum is regarded as a long-lived quantity, whose dynamics is described by an emergent hydrodynamic theory. Actually, such hydrodynamic behaviors have been reported, since 2016, in various ultrapure materials such as GaAs quantum wells [1], 2D monovalent layered metal PdCoO2 [2], Weyl semimetal WP2 [3] and graphene [4-6] through various unconventional DC transport phenomena. However, in spite of a rapidly increasing number of reports on the candidates, it remains an unexplored important issue what kind of roles the crystal symmetry and the geometry of Bloch electrons play in the hydrodynamic transport. In this work [7], we formulate the hydrodynamic theory for time-reversal-symmetry preserved noncentrosymmetric metals. The obtained equations reveal the emergence of unprecedented anomalous forces in the Euler equation, which highlights an unexpected analogy between our fluids and the inviscid chiral fluids in vacuum. It is remarkable that this analogy indicates the existence of vorticity-induced electric current (we refer to it as generalized vortical effect) in condensed matter without nontrivial topology, which is a phenomenon analogous to the chiral vortical effect in chiral fluids. In particular, we reveal that this novel phenomenon gives rise to a novel anomalous hydrodynamic flow, that is, the anomalous edge current and the asymmetric Poiseuille flow. Furthermore, our theory is also able to describe the hydrodynamic counterparts of various nonlinear anomalous transport phenomena which has been formulated so far only in dissipative or ballistic regime. For example, the anomalous transport corresponding to so-called the quantum nonlinear Hall effect and the magnus Hall effect are integrated into a unified framework described by the velocity field in our work. Furthermore, towards an experimental observation of the predicted phenomena, we provide a symmetry consideration on the existing hydrodynamic materials and also give a quantitative estimation of the observable quantities, based on an effective model for strained-TMD and graphene.
In highly conductive metals with sufficiently strong momentum-conserving scattering, the electron momentum is regarded as a long-lived quantity, whose dynamics is described by an emergent hydrodynamic theory. Actually, such hydrodynamic behaviors have been reported, since 2016, in various ultrapure materials such as GaAs quantum wells [1], 2D monovalent layered metal PdCoO2 [2], Weyl semimetal WP2 [3] and graphene [4-6] through various unconventional DC transport phenomena. However, in spite of a rapidly increasing number of reports on the candidates, it remains an unexplored important issue what kind of roles the crystal symmetry and the geometry of Bloch electrons play in the hydrodynamic transport. In this work [7], we formulate the hydrodynamic theory for time-reversal-symmetry preserved noncentrosymmetric metals. The obtained equations reveal the emergence of unprecedented anomalous forces in the Euler equation, which highlights an unexpected analogy between our fluids and the inviscid chiral fluids in vacuum. It is remarkable that this analogy indicates the existence of vorticity-induced electric current (we refer to it as generalized vortical effect) in condensed matter without nontrivial topology, which is a phenomenon analogous to the chiral vortical effect in chiral fluids. In particular, we reveal that this novel phenomenon gives rise to a novel anomalous hydrodynamic flow, that is, the anomalous edge current and the asymmetric Poiseuille flow. Furthermore, our theory is also able to describe the hydrodynamic counterparts of various nonlinear anomalous transport phenomena which has been formulated so far only in dissipative or ballistic regime. For example, the anomalous transport corresponding to so-called the quantum nonlinear Hall effect and the magnus Hall effect are integrated into a unified framework described by the velocity field in our work. Furthermore, towards an experimental observation of the predicted phenomena, we provide a symmetry consideration on the existing hydrodynamic materials and also give a quantitative estimation of the observable quantities, based on an effective model for strained-TMD and graphene.
[1] L. W. Molenkamp and M. J. M. de Jong, Phys. Rev. B 49, 5038 (1994).
[2] P. J. W. Moll, et al., Science 351, 1061 (2016),
[3] J. Gooth, et al., Nature Communications 9, 4093 (2018).
[4] D. A. Bandurin, et al., Science 351, 1055 (2016).
[5] J. Crossno, et al., Science 351, 1058 (2016).
[6] R. K. Kumar, et al., Nature Physics 13, 1182 (2017).
[7] RT, K. Takasan, N. Kawakami, arXiv:2005.03406 (2020).
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)
