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arXiv · 1508.00376

Observation of Spin-Dependent Charge Symmetry Breaking in $\Lambda N$ Interaction: Gamma-Ray Spectroscopy of $^4_{\Lambda }$He

T. O. Yamamoto·M. Agnello·Y. Akazawa·N. Amano·K. Aoki·E. Botta·N. Chiga·H. Ekawa·P. Evtoukhovitch·A. Feliciello·M. Fujita·T. Gogami·S. Hasegawa·S. H. Hayakawa·T. Hayakawa·R. Honda·K. Hosomi·S . H. Hwang·N. Ichige·Y. Ichikawa·M. Ikeda·K. Imai·S. Ishimoto·S. Kanatsuki·M. H. Kim·S. H. Kim·S. Kinbara·T. Koike·J . Y. Lee·S. Marcello·K. Miwa·T. Moon·T. Nagae·S. Nagao·Y. Nakada·M. Nakagawa·Y. Ogura·A. Sakaguchi·H. Sako·Y. Sasaki·S. Sato·T. Shiozaki·K. Shirotori·H. Sugimura·S. Suto·S. Suzuki·T. Takahashi·H. Tamura·K. Tanabe·K. Tanida·Z. Tsamalaidze·M. Ukai·Y. Yamamoto·S. B. Yang
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Abstract

The energy spacing between the ground-state spin doublet of $^4_\Lambda $He(1$^+$,0$^+$) was determined to be $1406 \pm 2 \pm 2$ keV, by measuring $\gamma$ rays for the $1^+ \to 0^+$ transition with a high efficiency germanium detector array in coincidence with the $^4$He$(K^-,\pi^-)$ $^4_\Lambda $He reaction at J-PARC. In comparison to the corresponding energy spacing in the mirror hypernucleus $^4_\Lambda $H, the present result clearly indicates the existence of charge symmetry breaking (CSB) in $\Lambda N$ interaction. It is also found that the CSB effect is large in the $0^+$ ground state but is by one order of magnitude smaller in the $1^+$ excited state, demonstrating that the $\Lambda N$ CSB interaction has spin dependence.

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T. O. Yamamoto, M. Agnello, Y. Akazawa, N. Amano, K. Aoki, E. Botta, N. Chiga, H. Ekawa, P. Evtoukhovitch, A. Feliciello, M. Fujita, T. Gogami, S. Hasegawa, S. H. Hayakawa, T. Hayakawa, R. Honda, K. Hosomi, S . H. Hwang, N. Ichige, Y. Ichikawa, M. Ikeda, K. Imai, S. Ishimoto, S. Kanatsuki, M. H. Kim, S. H. Kim, S. Kinbara, T. Koike, J . Y. Lee, S. Marcello, K. Miwa, T. Moon, T. Nagae, S. Nagao, Y. Nakada, M. Nakagawa, Y. Ogura, A. Sakaguchi, H. Sako, Y. Sasaki, S. Sato, T. Shiozaki, K. Shirotori, H. Sugimura, S. Suto, S. Suzuki, T. Takahashi, H. Tamura, K. Tanabe, K. Tanida, Z. Tsamalaidze, M. Ukai, Y. Yamamoto, S. B. Yang. 2015-08-03. Observation of Spin-Dependent Charge Symmetry Breaking in $\Lambda N$ Interaction: Gamma-Ray Spectroscopy of $^4_{\Lambda }$He. https://doi.org/10.1103/physrevlett.115.222501

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