Document Type


Publication Date




Publication Title

Progress of Theoretical and Experimental Physics






013D01 (1-19)


The small binding energy of the hypertriton leads to predictions of the non-existence of bound hypernuclei for isotriplet three-body systems such as nnΛ. However, invariant mass spectroscopy at GSI has reported events that may be interpreted as the bound nnΛ state. The nnΛ state was sought by missing-mass spectroscopy via the (e, e′K+) reaction at Jefferson Lab’s experimental Hall A. The present experiment has higher sensitivity to the nnΛ-state investigation in terms of better precision by a factor of about three. The analysis shown in this article focuses on the derivation of the reaction cross-section for the 3H(γ*, K+)X reaction. Events that were detected in an acceptance, where a Monte Carlo simulation could reproduce the data well (⁠ƍp/p⎮ < 4%), were analyzed to minimize the systematic uncertainty. No significant structures were observed with the acceptance cuts, and the upper limits of the production cross-section of the nnΛ state were obtained to be 21 and 31nbsr-1 at the 90% confidence level when theoretical predictions of (−BΛ, Γ) = (0.25, 0.8) MeV and (0.55, 4.7) MeV, respectively, were assumed. The cross-section result provides valuable information for examining the existence of nnΛ.


© The Authors 2021.

This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

Original Publication Citation

Suzuki, K.N. Gogami, T., Pandey, B. ... Ye, Z. Zhang, J. & Zheng, X. (2022). The cross-section measurement for the 3H (e, e', K+) nnΛ reaction. Progress of Theoretical and Experimental Physics, 2022(1), 1-19, Article 013D01.


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