RIKEN ECL Research Team / RIKEN ECL Research Unit Meson RIKEN ECL Research Team

RIKEN ECL Team Leader: Tadashi Hashimoto (Ph.D)

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Research Summary

We are conducting experiments aimed at generating a novel form of nuclei or matter where a meson is bound as a real particle, although mesons are typically considered virtual particles within a nucleus. Specifically, our focus lies in embedding a kaon, which contains a strange quark, into nuclei. It is suggested that the density of kaonic nuclei increases, potentially revealing new properties and quark degrees of freedom within the nucleus.
Furthermore, we are engaged in interdisciplinary research, such as muon atomic experiments, utilizing state-of-the-art superconducting X-ray detectors known as TES detectors.

Main Research Fields

Mathematical & Physical Sciences

Related Research Fields

Interdisciplinary Science & Engineering
Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
Quantum beam science-related

Keywords

Nuclear physics
Hadron physics
Superconducting X-ray detectors

Selected Publications

1. T. Akaishi, et al. (J-PARC E73/T77 collaboration):
"Precise lifetime measurement of ⁴_ΛH hypernucleus using in-flight ⁴He(K^-, π⁰) 4_ΛH reaction"
Phys. Lett. B 845, 138128 (2023).
2. T. Okumura et al.:
"A Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-ray Spectroscopy of Muonic Neon"
Phys. Rev. Lett. 130, 173001 (2023).
3. S. Aikawa et al. (J-PARC E31 collaboration):
"Pole Position of Λ(1405) Measured in d(K^-, n)πΣ Reactions"
Phys. Lett. B 837, 137637 (2022).
4. T. Hashimoto et al. (J-PARC E62 collaboration):
"Measurements of Strong-Interaction Effects in Kaonic-Helium Isotopes at Sub-eV Precision with X-Ray Microcalorimeters"
Phys. Rev. Lett. 128, 112503 (2022).
5. T. Okumura, et al.:
"Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X rays"
Phys. Rev. Lett. 127, 053001 (2021).
6. T. Yamaga, et al. (J-PARC E15 collaboration):
"Observation of a K^barNN bound state in the ³He(K^-, n) reaction"
Phys. Rev. C 102, 044002 (2020).
7. S. Okada et al.:
"First application of superconducting transition-edge-sensor microcalorimeters to hadronic-atom x-ray spectroscopy"
Prog. Theor. Exp. Phys. 2016, 091D01 (2016).
8. S. Ajimura et al. (J-PARC E15 collaboration):
"K^-pp", a K^bar-meson nuclear bound state, observed in ³He(K^-,Λp)n reactions"
Physics Letters B 789, 620 (2019).
9. Y. Sada et al. (J-PARC E15 collaboration):
"Structure near the K^-+p+p threshold in the in-flight ³He(K^-,Λp)n reaction"
Prog. Theor. Exp. Phys. 2016, 051D01 (2016).
10. T. Hashimoto et al. (J-PARC E15 collaboration):
"Search for the deeply bound K^-pp state from the semi-inclusive forward-neutron spectrum in the in-flight K^- reaction on helium-3"
Prog. Theor. Exp. Phys. 2015, 061D01 (2015).

Lab Members

Principal investigator

Tadashi Hashimoto: RIKEN ECL Team Leader

Contact Information

317 Nishina RIBF Bldg.,
2-1 Hirosawa,
Wako, Saitama
351-0198, Japan
Email: tadashi.hashimoto [at] riken.jp