We revisit constraints on decaying very heavy dark matter (VHDM) using the latest ultrahigh-energy cosmic-ray (UHECR; E >1e18 eV) data and ultrahigh-energy (UHE) gamma-ray flux upper limits, measured by the Pierre Auger Observatory. We present updated limits on the VHDM lifetime for masses up to ∼ 1e15 GeV, considering decay into quarks, leptons, and massive bosons. In particular, we consider not only the UHECR spectrum but their composition data that favors heavier nuclei. Such a combined analysis improves the limits at <1e12 GeV because VHDM decay does not produce UHECR nuclei. We also show that the constraints from the UHE gamma-ray upper limits are ∼ 10 times more stringent than that obtained from cosmic rays, for all of the Standard Model final states we consider. The latter improves our limits to VHDM lifetime by a factor of two for dark matter mass >1e12 GeV. We also provide constraints using neutrino flux from dark matter decay, including the neutrino-induced cascades. We consider the interaction of UHE neutrinos with the cosmic neutrino background, leading to the attenuation of the extragalactic flux reaching Earth, which improves our analysis to obtain tighter constraints.

Most organisms exhibit a periodic activity of about 24 h. This circadian rhythm is considered to be an adaptation to the fluctuations of the environment. In social insects such as honeybees and ants, individual behavior, including activity-rest rhythms, is influenced by interactions within the colony. However, it is challenging to monitor individual activity-rest rhythms in an ant colony due to their large group size and small body size. To address this, we developed an image-based tracking system using 2D barcodes a monomorphic ant and measured the locomotor activities of all colony members under laboratory conditions. Activity-rest rhythms appeared only in isolated ants, not under colony conditions. This suggests that a mixture of social interactions, not light and temperature, induces the loss of activity-rest rhythms. These findings contribute to our understanding of the diverse patterns of circadian activity rhythms in social insects.

This event will be conducted in Japanese.

Program

14:00-14:05 Welcome address T. Hatsuda (RIKEN iTHEMS)

14:05-15:35
T. Tada (RIKEN iTHEMS)
"Toward understanding of the origin of spacetime"
(This talk is in English)

15:35-16:00 coffee break

16:00-16:30
Shin Nakamura (Chuo Univ.)
"Application of gauge/gravity duality: application to non-equilibrium physics"
(This talk is in Japanese)

16:30-17:00
Kinya Oda (Tokyo Woman's Chiristian Univ.)
"Gaussian formalism: From Hesenberg's Uncertainty Principle to Time-Boundary Effect and Lorentz-Covariant Complete Basis for Spinors"
(This talk is in Japanese)

17:00-17:30
Gen Tatara (RIKEN, CEMS)
"Some topics of spintronics"
(This talk is in Japanese)

17:30-18:00
Asato Tsuchiya (Shizuoka Univ.)
"Recent progress in the studies of the emergence of space-time in the type IIB matrix model"
(This talk is in Japanese)

18:15-
informal discussion
@ Common space on 3F of the main research building

14:45-15:00 Teatime discussion
15:00-16:00 Talk by Dr. Wataru Morita (Researcher, Department of Anthropology, National Museum of Nature and Science / Associate Professor, Department of Biological Sciences, Graduate School of Science, The University of Tokyo)
16:15-17:20 2024 Study Group introduction session
17:30-18:30 Discussion

Thanks to intensive research efforts, topology has been established as a fundamental concept in physics. For closed quantum systems, the classification of gapped topological phases has matured. Moreover, the importance of topology is not limited to isolated quantum systems. Recently, the topology of non-Hermitian Hamiltonians, which effectively describe systems with dissipation, has attracted much attention worldwide. This fascination is exemplified by topological phases and topological phenomena unique to non-Hermitian systems.

Against this background, the primary purpose of this workshop is to bring together researchers working on topological phases and to discuss (i) open questions in topological phases of closed quantum systems and (ii) the role of topology in open quantum systems and measurements.