Spectroscopic study of a possible <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>n</mml:mi><mml:mi>n</mml:mi></mml:mrow></mml:math> resonance and a pair of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">Σ</mml:mi><mml:mi>N</mml:mi><mml:mi>N</mml:mi></mml:mrow></mml:math> states using the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>(</mml:mo><mml:mi>e</mml:mi><mml:mo>,</mml:mo><mml:msup><mml:mi>e</mml:mi><mml:mo>′</mml:mo></mml:msup><mml:msup><mml:mi>K</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>)</mml:mo></mml:mrow></mml:math> reaction with a tritium target
B. Pandey, L. Tang, T. Gogami, Kanichi Suzuki, Kosuke Itabashi, S. Nagao, K. Okuyama, S. N. Nakamura, D. Abrams, I. R. Afnan, T. Akiyama, D. Androić, K. Aniol, T. Averett, C. Ayerbe Gayoso, J. Bane, S. Barcus, J. Barrow, Vincenzo Bellini, H. Bhatt, D. Bhetuwal, Diptaparna Biswas, A. Camsonne, J. Castillo Castellanos, J-P. Chen, Jianping Chen, S. Covrig, D. Chrisman, R. Cruz-Torres, Rasel Das, E. Fuchey, C. Gal, Benjamin F. Gibson, 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, Tea 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
A mass spectroscopy experiment with a pair of nearly identical high-resolution spectrometers and a tritium target was performed in Hall A at Jefferson Lab. Utilizing the $(e,{e}^{\ensuremath{'}}{K}^{+})$ reaction, enhancements, which may correspond to a possible $\mathrm{\ensuremath{\Lambda}}nn$ resonance and a pair of $\mathrm{\ensuremath{\Sigma}}NN$ states, were observed with an energy resolution of about 1.21 MeV ($\ensuremath{\sigma}$), although greater statistics are needed to make definitive identifications. An experimentally measured $\mathrm{\ensuremath{\Lambda}}nn$ state may provide a unique constraint in determining the $\mathrm{\ensuremath{\Lambda}}n$ interaction, for which no scattering data exist. In addition, although bound $A=3$ and 4 $\mathrm{\ensuremath{\Sigma}}$ hypernuclei have been predicted, only an $A=4 \mathrm{\ensuremath{\Sigma}}$ hypernucleus ($_{\mathrm{\ensuremath{\Sigma}}}^{4}\mathrm{He}$) was found, utilizing the $({K}^{\ensuremath{-}},{\ensuremath{\pi}}^{\ensuremath{-}})$ reaction on a $^{4}\mathrm{He}$ target. The possible bound $\mathrm{\ensuremath{\Sigma}}NN$ state is likely a ${\mathrm{\ensuremath{\Sigma}}}^{0}nn$ state, although this has to be confirmed by future experiments.