Masahiro Nozaki, RIKEN
Signature of quantum chaos in operator entanglement in 2d CFTs
Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
We study operator entanglement measures of the unitary evolution operators of (1+1)-dimensional conformal field theories (CFTs), aiming to uncover their scrambling and chaotic behaviors. In particular, we compute the bi-partite and tri-partite mutual information for various configurations of input and output subsystems, and as a function of time. We contrast three different CFTs: the free fermion theory, compactified free boson theory at various radii, and CFTs with holographic dual. We find that the bi-partite mutual information exhibits distinct behaviors for these different CFTs, reflecting the different information scrambling capabilities of these unitary operators; while a quasi-particle picture can describe well the case the free fermion and free boson CFTs, it completely fails for the case of holographic CFTs. Similarly, the tri-partite mutual information also distinguishes the unitary evolution operators of different CFTs. In particular, its late-time behaviors, when the output subsystems are semi-infinite, are quite distinct for these theories. We speculate that for holographic theories the late-time saturation value of the tri-partite mutual information takes the largest possible negative value and saturates the lower bound among quantum field theories.
Kohei Kamada, RESCEU, The University of Tokyo
Primordial magnetic fields and their roles in particle physics and cosmology
Meeting room 3, Kenkyu honkan 1F, slides (kek.jp only)
Recent observations of TeV blazars by Fermi identified deficits of secondary GeV cascade photons. These observations can be explained by intergalactic magnetic fields, which may have a primordial origin. If the magnetic fields are helical and generated in the early Universe such as before the electroweak symmetry breaking, nontrivial interaction between (hyper)magnetic fields and other particles can cause some interesting and non negligible phenomena in the early Universe. In this talk, I will show that the baryon asymmetry can be generated by the chiral anomaly, and depending on the detail of electroweak cross over, baryon asymmetry is not completely washed out by the electroweak sphalerons. Thus, this mechanism can be responsible for the present baryon asymmetry of the Universe. If this mechanism is responsible for the present Universe, the BSM physics is needed for the generation of (hyper)magnetic fields but not for the baryogenesis. I will also discuss possible mechanism to generate such helical hypermagnetic fields suitable for the baryogenesis scenario.
松原隆彦, KEK
実験屋のためのマルチバース
Room 346, 4 go-kan
私たちに観測できる宇宙はひとつしかない。最近では、理論的にマルチバースの可能性に関する学説がさかんに提案されるようになってきた。マルチバースは一般に破壊的とも言える説明能力を持っているがゆえに、検証可能性に乏しい。理論的に好ましければそれは存在していると見なせるのだろうか、それとも観測することができなければ存在しているとは言えないのだろうか。問題は哲学的でもあり、現時点で結論を出すことはできないが、マルチバースの可能性とどう付き合っていけばよいのかについて一緒に考えてみたい。
Monika Blanke, Institute for Nuclear Physics (IKP), Karlsruhe Institute of Technology
Status of New Physics in Lepton Flavour Universality Violating B Decays
Seminar Room, Kenkyu honkan 3F
Recent data from LHCb and the B factories exhibit intriguing deviations from the Standard Model in B decay observables related to lepton flavour universality violation. I will review the current status of these anomalies and outline the possible diections in BSM model building to address them. I will then introduce a specific BSM model, which is based on the Pati-Salam gauge group in the 5-dimensional Randall-Sundrum spacetime.
Hirokazu Sasaki, The University of Tokyo
Neutrino oscillations in core-collapse supernovae and their effects on nucleosynthesis
Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
Neutrinos are produced inside astrophysical sites such as the Sun, core-collapse supernovae, blazars and neutron-star mergers. Such neutrinos would change their flavors significantly owing to refractive effects of background electrons and neutrinos themselves. In core-collapse supernovae, large numbers of neutrinos are produced and emitted from the proto-neutron star after core-bounce. It is considered that collective neutrino oscillations are caused by self-interacting neutrinos near the proto-neutron star (~100 km). Such refractive effect increases energetic (anti)electron neutrinos, which is expected to affect supernova explosion and nucleosynthesis. We show a numerical result of neutrino oscillations in core-collapse supernovae and mention how collective neutrino oscillations enhance nucleosynthesis in neutrino-driven winds. Our result would be helpful to more realistic studies to reveal the origin of solar-system isotopic abundances of p-nuclei.
Goro Ishiki, University of Tsukuba
Diffeomorphisms and Berezin-Toeplitz quantization for fuzzy spaces
Seminar room, Kenkyu honkan 3F
In the matrix model formulations of string/M- theories, geometry of strings/branes is expressed in terms of configurations of matrices. We discuss how the diffeomorphism, which is one of the most important symmetry in the world volume theory of strings and branes, is realized in the configuration space of matrices. We show that the diffeomorphism for matrices can be defined by using the so-called Berezin-Toeplitz quantization. As an example, we consider the fuzzy S^2 and explicitly construct the matrix version of the holomorphic diffeomorphisms on the fuzzy S^2.
Yoshifumi Hyakutake, Ibaraki University
Inflationary Cosmology via Quantum Corrections in M-theory
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
Inflation is a promising scenario to resolve problems of big bang cosmology, such as horizon problem. Although there are a lot of models which realize the inflation, it is natural to explain it in the framework of quantum gravity. In this talk, we consider 11 dimensional M-theory, which consists of the 11 dimensional supergravity and quartic terms of the Weyl tensor, as the theory of quantum gravity, and investigate inflationary cosmology by analyzing the effective action of the M-theory. We will show that the classical solution of the 11 dimensional supergravity does not represent the inflationary expansion, but if we include the quantum corrections, the behavior of the solution around the very early time is modified and the inflationary scenario is realized.
Alexander Kusenko, UCLA and Kavli IPMU
Primordial black holes as dark matter
Meeting room 3, Kenkyu honkan 1F
I will discuss new and rather generic scenarios for production of black holes in the early universe. In some mass range, such black holes can account for all dark matter. Primordial black holes can also contribute to synthesis of heavy elements by disrupting neutron stars.
Takeru Yokota, Department of Physics, Kyoto University
Functional renormalization group-aided density-functional theory - application to one-dimensional nuclear matter and two-dimensional electron gas -
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
The functional renormalization group-aided density-functional analysis (FRG-DFT) starts to be applied to realistic models of quantum many-body systems. Recently we have developed a new FRG-DFT formalism, which is suitable for analyzing systems with an infinite number of particles with fixed densities. In this talk, I will present our formalism and our two applications: The first one is the calculation of the equation of state (EOS) and the density-density spectral function of an infinite nuclear matter (NM) in (1+1) dimensions composed of spinless nucleons. The resultant EOS of the NM coincides with that obtained by the Monte-Carlo method within a few percents for the available range of density. We also reproduce a notable feature of the density spectral function of the non-linear Tomonaga-Luttinger liquid: The spectral function has singularities at the edge of its support at the lower-energy side. Subsequently, I will show our FRG-DFT analysis of the two-dimensional homogeneous electron gas, which is the first application of FRG-DFT to two-dimensional systems. We find that the result of FRG-DFT reproduces the exact correlation energy at the high-density limit and is consistent with the Monte-Carlo results for the high- and mid-density cases. Our study demonstrates that the FRG-DFT can be a promising method to analyze quantum many-body systems.
Yu-tin Huang, Department of Physics, National Taiwan University
Build the wall and drain the swamp: positive constraints on EFT from the UV
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
