原子核を形作る力の理解に新展開 －ハイパー三重水素原子核を世界最高精度測定－

2026-04-17 東京大学

崩壊パイ中間子分光法により今回新たに測定されたハイパー三重水素原子核

＜関連情報＞

• https://www.s.u-tokyo.ac.jp/ja/press/11121/#
• https://journals.aps.org/prl/abstract/10.1103/19gd-jqw2

精密測定Λ-結合エネルギー差Λ3HそしてΛ4HMAMIの崩壊パイオン分光法による Precise Measurement of the Λ-Binding-Energy Difference between Λ3H and Λ4H via Decay-Pion Spectroscopy at MAMI

Ryoko Kino, Sho Nagao, Patrick Achenbach, Satoshi N. Nakamura, Josef Pochodzalla, Takeru Akiyama, Ralph Böhm, Mirco Christmann, Michael O. Distler et al. (A Collaboration)
Physical Review Letters  Published: 17 April, 2026
DOI: https://doi.org/10.1103/19gd-jqw2

Abstract

We performed high-precision decay-pion spectroscopy of light Λ hypernuclei at the Mainz Microtron (MAMI) using the A1 spectrometer facility. By measuring the monochromatic ⁻ momentum from the two-body weak decay _Λ³H→⁢³He+⁻ and referencing it to the _Λ⁴H→⁢⁴He+⁻ decay, we determined the Λ binding energy of _Λ³H with unprecedented accuracy. The obtained value, _Λ(_Λ³H)=0.523±0.01⁢3_stat±0.07⁢5_syst.  MeV, is consistent with the STAR result, but indicates a significantly deeper binding than inferred from earlier measurements. This result implies a stronger Λ-deuteron interaction and provides stringent constraints on hyperon-nucleon interactions.