The cross-section measurement for the 3H(<i>e, e</i>′<i>K</i>+)<i>nn</i>Λ reaction
Kanichi Suzuki, T. Gogami, B. Pandey, Kosuke Itabashi, S. Nagao, K. Okuyama, Shintaro Nakamura, L. Tang, D. Abrams, T. Akiyama, D. Androić, K. Aniol, C. Ayerbe Gayoso, J. Bane, S. Barcus, J. Barrow, Vincenzo Bellini, H. Bhatt, D. Bhetuwal, D. Biswas, A. Camsonne, J. Castillo Castellanos, J-P Chen, J. Chen, S. Covrig, D. Chrisman, R. Cruz-Torres, Rasel Das, E. Fuchey, K. Gnanvo, F. Garibaldi, T. Gautam, J. Gómez, P. Guèye, T. J. Hague, O. Hansen, W. Henry, F. Hauenstein, D. W. Higinbotham, C. E. Hyde-Wright, M. Kaneta, C. Keppel, T. Kutz, N. Lashley-Colthirst, S. Li, H. Liu, J. Mammei, P. Markowitz, R. E. McClellan, F. Meddi, D. Meekins, R. Michaels, M. Mihovilovič, A. Moyer, D. Nguyen, M. Nycz, V. Owen, C. Palatchi, S. Park, Tomislav Petković, S. Premathilake, P. E. Reimer, J. Reinhold, S. Riordan, V. M. Rodriguez, C. Samanta, S. N. Santiesteban, B. Sawatzky, S. Širca, K. Slifer, T. Su, Y. Tian, Yuichi Toyama, K. Uehara, G. M. Urciuoli, D. Votaw, Jeffrey F. Williamson, B. Wojtsekhowski, S. A. Wood, B. Yale, Z. Ye, J. Zhang, Xiaochao Zheng
Abstract
Abstract 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 ($|\delta p/p| \lt 4\%$), 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 $31 \, \rm {nb} \, \rm {sr}^{-1}$ 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.