Do you remember an astounding news of the first detection of primordial gravitational waves from Inflation (PGWs) on March 2014 by the BICEP2 experiment at the South Pole. How many people outside the field understand a full account of the news? In this article, we explain why their detection of PGWs via the CMB B-mode polarization was wrong. We also describe the current status of measurements of PGWs and its prospect for the next 10 years based on the results, achievements, and future plan of the Polarbear experiment that Japan has contributed to.
Molecules, either chiral or achiral, sometimes form chiral structures in crystallization. Viedma discovered a remarkable chirality conversion of crystals by simply grinding crystals in a solution. Although the phenomenon is simple, the underlying mechanism is still controversial. In this article, by using a simple reaction model and generalized Becker–Döring model, we show that the idea of cluster incorporation to crystals can explain various anomalous features of related experiments.
When Coulomb interaction between holes and electrons is not screened well in a semimetal or a narrow gap semiconductor, the holes and electrons may undergo coherent formation of excitons and the system may fall in an excitonic insulator. We have studied the electronic structure of Ta2NiSe5 which is one of the candidates for the excitonic insulator. The Ni 2p core level photoemission suggests that Ni 3d band is partly unoccupied indicating unusual hybridization between the Ni 3d valence band and the Ta 5d conduction band. By means of state-of-the-art time-resolved ARPES, we have realized a photoinduced phase transition from the possible excitonic insulator phase to a semimetal phase in Ta2NiSe5 and related systems. The ultrafast dynamics of the photoinduced phase transition indicates that Ta2NiSe5 can be viewed as an excitonic insulator with direct band gap.
A theoretical solution to the self-excited Hawkes process is reviewed on the basis of the Markov embedding and field master equation. This review is based on our two articles: K. Kanazawa and D. Sornette, Phys. Rev. Lett. 125, 138301(2020) and Phys. Rev. Res. 2, 033442(2020).