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arXiv · 1408.5637

Search for the deeply bound $K^-pp$ state from the semi-inclusive forward-neutron spectrum in the in-flight $K^-$ reaction on helium-3

Abstract

An experiment to search for the $K^-pp$ bound state was performed via the in-flight $^3$He($K^-,n)$ reaction using 5.3 $\times$ $10^9$ kaons at 1 GeV/$c$ at the J-PARC hadron experimental facility. In the semi-inclusive neutron missing-mass spectrum at $\theta_{n}^{lab}=0^\circ$, no significant peak was observed in the region corresponding to $K^-pp$ binding energy larger than 80 MeV, where a bump structure has been reported in the $\Lambda p$ final state in different reactions. Assuming the state to be isotropically decaying into $\Lambda p$, mass-dependent upper limits on the production cross section were determined to be 30--180, 70--250, and 100--270 $\mu$b/sr, for the natural widths of 20, 60, and 100 MeV, respectively, at 95\% confidence level.

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Tadashi Hashimoto, Shuhei Ajimura, George Beer, Hyoungchan Bhang, Mario Bragadireanu, Luigi Busso, Michael Cargnelli, Seonho Choi, Catalina Curceanu, Shun Enomoto, Diego Faso, Hiroyuki Fujioka, Yuya Fujiwara, Tomokazu Fukuda, Carlo Guaraldo, Ryugo S. Hayano, Toshihiko Hiraiwa, Masami Iio, Mihai Iliescu, Kentaro Inoue, Yosuke Ishiguro, Takashi Ishikawa, Shigeru Ishimoto, Kenta Itahashi, Masaaki Iwai, Masahiko Iwasaki, Yuko Kato, Shingo Kawasaki, Paul Kienle, Hiroshi Kou, Yue Ma, Johann Marton, Yasuyuki Matsuda, Yutaka Mizoi, Ombretta Morra, Tomofumi Nagae, Hiroyuki Noumi, Hiroaki Ohnishi, Shinji Okada, Haruhiko Outa, Kristian Piscicchia, Marco Poli Lener, Antonio Romero Vidal, Yuta Sada, Atsushi Sakaguchi, Fuminori Sakuma, Masaharu Sato, Alessandro Scordo, Michiko Sekimoto, Hexi Shi, Diana Sirghi, Florin Sirghi, Shoji Suzuki, Takatoshi Suzuki, Kiyoshi Tanida, Hideyuki Tatsuno, Makoto Tokuda, Dai Tomono, Akihisa Toyoda, Kyo Tsukada, Oton Vazquez Doce, Eberhard Widmann, Takumi Yamaga, Toshimitsu Yamazaki, Heejoong Yim, Qi Zhang, Johann Zmeskal. 2014-08-24. Search for the deeply bound $K^-pp$ state from the semi-inclusive forward-neutron spectrum in the in-flight $K^-$ reaction on helium-3. https://doi.org/10.1093/ptep/ptv076

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