First observation of a nuclear s-state of a $\Xi$ hypernucleus, $^{15}_{\Xi}{\rm C}$. (22nd July 2021)

• Record Type: Journal Article
• 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;
• Is Part Of: Progress of theoretical and experimental physics. Volume 2021:Number 7(2021)
• Publication Date: 2021-07-22
• Subjects: D00 -- D14 -- D25 -- D29; Physics -- Periodicals; Mathematical physics -- Periodicals; 530.05
• DOI: 10.1093/ptep/ptab073
• Languages: English
• ISSNs: 2050-3911

Abstract

Abstract: 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 $\Xi^-+^{14}\!\, \!\!{\rm N}\to^{5}_{\Lambda}\!\!\!{\rm He} + ^{5}_{\Lambda}\!\!{\rm He} + ^{4}\!\!{\rm He} + \mathrm{n}$ . Since there are no excited states for daughter particles, the binding energy of the $\Xi^-$ hyperon, $B_{\Xi^-}$, in the $^{14}_{}{\rm N}$ nucleus was uniquely determined to be $6.27 \pm 0.27$ MeV. Another $\Xi^-$ –$^{14}_{}{\rm N}$ system via the decay $^{9}_{\Lambda}{\rm Be} + ^{5}_{\Lambda}\!\!\!{\rm He} + \mathrm{n}$ 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, $^{15}_{\Xi}{\rm C}$ .