First observation of a nuclear \(s\)-state of \(\Xi\) hypernucleus, \(^{15}_{\Xi}{\rm C}\)

• Published in: arXiv.org 2021-05
• Main Authors: Yoshimoto, M, Ahn, J K, Bassalleck, B, Ekawa, H, Endo, Y, Fujita, M, Han, Y, Hashimoto, T, Hayakawa, S H, Hicks, K, Hoshino, K, Hoshino, S, Hwang, S H, Ichikawa, Y, Ichikawa, M, Imai, K, Ishikawa, Y, Kanauchi, H, Kasagi, A, Kim, S H, Kinbara, S, Lin, P M, Ma, T L, Miwa, K, Moe, A T, Nagase, Y, Nakazawa, K, Nanamura, T, Naruki, M, Nyaw, A N L, Pochodzalla, J, Sako, H, Sato, S, Soe, M M, Soe, M K, Sohn, J Y, Takahashi, H, Takahashi, T, Tamura, H, Tanida, K, Theint, A M M, Tint, K T, Ukai, M, Yamamoto, T O, Yang, S B, Yoon, C S, Yoshida, J, Zhang, D H, Zhang, Z
• Format: Article
• Language: English
• Subjects: Decay; Excitation; Hypernuclei
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2103.08793

Bound-systems of \(\Xi^-\)--\(^{14}_{}{\rm N}\) are studied via \(\Xi^-\) capture at rest followed by emission of a twin single-\(\Lambda\) hypernucleus in the emulsion detectors. Two events forming extremely deep \(\Xi^-\) bound states were obtained by analysis of a hybrid method in the E07 experiment at J-PARC and reanalysis of the E373 experiment at KEK-PS. The decay mode of one event was assigned as \(\Xi^-+^{14}_{}{\rm N}\to^{5}_{\Lambda}{\rm He}\)+\(^{5}_{\Lambda}{\rm He}\)+\(^{4}_{}{\rm He}\)+n. Since there are no excited states for daughter particles, the binding energy of the \(\Xi^-\) hyperon, \(B_{\Xi^-}\), in \(^{14}_{}{\rm N}\) nucleus was uniquely determined to be 6.27 \(\pm\) 0.27 MeV. Another \(\Xi^-\)--\(^{14}_{}{\rm N}\) system via the decay \(^{9}_{\Lambda}{\rm Be}\) + \(^{5}_{\Lambda}{\rm He}\) + n brings a \(B_{\Xi^-}\) value, 8.00 \(\pm\) 0.77 MeV or 4.96 \(\pm\) 0.77 MeV, where the two possible values of \(B_{\Xi^-}\) correspond to the ground and the excited states of the daughter \(^{9}_{\Lambda}{\rm Be}\) nucleus, respectively. Because the \(B_{\Xi^-}\) values are larger than those of the previously reported events (KISO and IBUKI), which are both interpreted as the nuclear \(1p\) state of the \(\Xi^-\)--\(^{14}_{}{\rm N}\) system, these new events give the first indication of the nuclear \(1s\) state of the \(\Xi\) hypernucleus, \(^{15}_{\Xi}{\rm C}\).