## 2021/12/13 (月)## Title: A brief introduction to the model of solid inflation †## Speaker: Koki Tokeshi †Abstract: Many inflationary models can be treated in the framework of the conventional effective field theory approach, in which the time translation symmetry slightly breaks to realize quasi de Sitter Universe [2]. The model of solid inflation, proposed and systematically analyzed in [1], gives an exception: the spatial translation symmetries are broken in the model. In this talk, I will review the model and introduce many unusual features stemmed from the drastically different symmetry breaking pattern. Since the scalar amplitude could be enhanced compared to the conventional prediction, I will also discuss possibility of black hole formation in the model [3]. ## 2021/11/29 (月)## Title: Introduction to generalized global symmetries and their application †## Speaker: Yoshimasa Hidaka †Ordinary symmetries are symmetries acting on point particles. The concept can be generalized to symmetries acting on extended objects, such as vortices and domain walls. Such symmetres are called higher form symmetries. In this talk, I review the concept of higher form symmetries. As an example of the application, I discuss spontaneous breaking of higher form symmetries in a nonrelativistic system and show the counting rule of the Nambu-Goldstone modes. ## 2021/11/22 (月)Dear all, Next RESCEU Monday seminar is on Nov. 22, 15:30-16:30. ======================================================================= ## Title:Two-group symmetry in QED †## Speaker:Fumio Uchida †Abstract: Refs: ## 2021/11/15 (月)## Title: Hawking radiation as quantum tunneling †## Speaker: Takumi Hayashi †Abstract: Hawking radiation is a thermal radiation induced by a black hole, which is predicted by quantum field theory in curved spacetime. There are several attempts to formulate Hawking radiation as quantum tunneling of an emitted particle, which succeed in capturing the feature of it. Since the tunneling method is simpler than the original field theory, there exist important applications to the dynamical black hole providing an insight into information loss paradox. [1] K. Srinivasan and T. Padmanabhan, Phys. Rev. D 60 (1999), 024007 ## 2021/11/8 (月)## Title: Chirality generation via Schwinger Effect -real time description for CME- †## Speaker: Jun'ya Kume †Abstract: The Chiral Magnetic Effect (CME) predicts electric current is induced by a magnetic field in the left-right asymmetric fermion background. Asymmetry of the background, or the transportation coefficient is conventionally expressed by the so-called chiral chemical potential. Due to such a proportionality, CME current is sometimes misunderstood as an equilibrium response, but it is not the case. In this talk, I will give a review on the Schwinger pair production with parallel E and B. Such a field configuration generates chiral asymmetry and chiral chemical potential does not enter in the production rate. In order to clarify the real-time nature of the CME, in-in evaluation of the chiral charge and the electric current is performed in such a system. References: ## 2021/11/1 (月)## Title: Universality class and the chiral phase transition in QCD †## Speaker: Kohei Fujikura †Landau-Ginzburg-Wilson (LGW) theory, based on the argument of universality, is a powerful effective theory that describes the dynamics of various phase transitions [1,2]. Pisarski and Wilczek constructed the LGW Hamiltonian of the QCD chiral phase transition and analyze the dynamics of the phase transition at one-loop order. They concluded that the phase transition is of (fluctuation-induced) first order for two or more massless quarks when U(1)_A is fully recovered during the phase transition [3]. In this talk, I will review the argument of universality and its application to QCD (chiral) phase transition. References: ## 2021/10/4 (月)## Singularities of Cosmological Correlators †## Jason Kristiano †Abstract: The structures of the cosmological correlators are controlled by their singularities [1,2], which are fixed in terms of the flat-space scattering amplitude [3]. By knowing their singularities, residues, and unitarity conditions, it is possible to determine the full structure of the correlators. This method was proposed by Baumann et. al. in their latest paper [1] within the spirit of the bootstrap method, much influenced by [2] and [3] paper. This will be a series of lectures, with tentative contents: (1) Oct 4: Singularities of flat-space correlators and de-Sitter space correlators. References: [1] D. Baumann, et. al., Linking the Singularities of Cosmological Correlators, arXiv:2106.05294 ## 2021/9/27 (月)## Gravitational Wave Probes of Dark Matter and the Baryon Asymmetry from Axion Rotations †## Raymond Co †Abstract: References: ## 2021/7/26 (月)## Title: On the excitation of black hole overtones †## Speaker: Naritaka Oshita †Abstract: Understanding the nature of quasinormal ringing of black holes is important in the context of ## 2021/7/19 (月)## Title: SU(N) gauge natural inflation †## Speaker: Tomohiro Fujita †Abstract: I'll discuss general attractor solutions for SU(N) gauge fields coupled to a rolling axion via the Chern-Simons interaction during inflation. It has been known that the SU(2) gauge field has an isotropic and homogeneous attractor solution, which leads to rich phenomenology including the amplification of primordial gravitational waves. We find a generic way to construct similar background solutions for SU(N), and enumerate all the isotropic stationary solutions for SU(3) and SU(4). We also confirm that numerical solutions with random initial conditions converge into these attractors. Interestingly, the gauge field amplitudes (i.e. VEVs) tend to increase as N of SU(N) grows, which may provide interesting observational signatures. ## 2021/7/12 (月)## Title: Black hole information paradox and fine grained entropy in gravitational system †## Speaker: Yusuke Yamada †Black hole information paradox has been one of the unsolved problems in quantum gravity. One can quantify the problem by looking at the behavior of the von Neumann entropy, which is also known as fine-grained entropy. Recently, the solution to the information paradox was proposed, which is the new rule to obtain improved fine-grained entropy formula in gravitational system. The improved formula gives the fine-grained entropy consistent with the unitarity. Refs: ## 2021/7/5 (月)## Title: Ceterum autem censeo, Gravitas esse quantizo †## Speaker: Kohei Kamada †Niels Bohr has once argued in his private communications Refs. ## 2021/6/28 (月)## Title: Environmental noise estimation and detector characterization of gravitational wave detectors †## Speaker: Jun’ichi Yokoyama †In the first part, I will introduce our recent paper References: ## 2021/6/21 (月)## An Introduction to skyrmions †## Fumio Uchida †Abstract: References: ## 2021/6/7 (月)## Title: Quantum Simulation (for cosmology?) †## Speaker: Soichiro Hashiba †Abstract: References: ## 2021/5/31 (月)## Inflationary bispectrum from symmetry and locality. †## Jason Kristiano †Abstract: Inflationary bispectrum was first derived by Maldacena in his famous paper [1]. Recently, inspired by the development of scattering amplitude in the particle physics community, some cosmologists are trying to derive inflationary bispectrum, or generally higher-point function, by only considering symmetries of cosmological perturbations. First, Nima Arkani-Hamed et. al. [2] successfully derived inflationary bispectrum by only using slightly broken de-Sitter space isometries. However, inflation generally breaks de-Sitter isometries, either small or large. For that motivation, Enrico Pajer et.al. [3-5] introduced a new bootstrap method without assuming de-Sitter isometries. In this seminar, I will review his method and compare the advantages and disadvantages to the previous one. References: ## 2021/5/24 (月)## Title: Primordial black holes from fifth forces †## Speaker: Koki Tokeshi †Primordial black holes could have formed in the early universe and various formation mechanisms have been proposed. Among them, I will review the relativly new one, first applied to PBHs in [1], in which the long range attractive forces between the light scalar and heavy fermion fields are exploited. I will also review the complementary paper [2], in which more general and quantitative analyses have been done, supporting the idea and estimations given in [1]. Related discussion about PBHs vs PMDHs in [3] and observational implications in [4] will also be reviewed. References: ## 2021/5/17 (月)## Title: Entanglement harvesting from vacuum in cosmology †## Speaker: Takumi Hayashi †Abstract: References: ## 2021/5/10 (月)## Title: Inflation from the point of view of quantum estimation theory †## Speaker: Jun’ya Kume †Abstract: Recently, application of the quantum estimation theory to inflation has been discussed in several works by C. Gomez and R. Jimenez. Focusing on two of their papers, I introduce their perspectives that the properties of primordial curvature perturbation generated during inflation can be quantum mechanically explained by the quantum Fisher information with respect to the appropriate parameter. After I briefly give a review on the quantum Fisher information and Cramer-Rao bound, I present how the amplitude and the tilt of the curvature perturbation can be related to the Fisher information with respect to the time and the energy scale, respectively. References: ## 2021/4/26 (月)## Title: Electroweak-like Baryogenesis with New Chiral Matter †## Speaker: Kohei Fujikura †Abstract: References: |

Last-modified: 2021-04-12 (月) 11:04:35 (284d)