학술논문
Observation of the '$K^-pp$'-like structure in the $d(\pi^+, K^+)$ reaction at 1.69 GeV/$c$
Document Type
Working Paper
Author
Ichikawa, Yudai; Nagae, Tomofumi; Fujioka, Hiroyuki; Bhang, Hyoungchan; Bufalino, Stefania; Ekawa, Hiroyuki; Evtoukhovitch, Petr; Feliciello, Alessandro; Hasegawa, Shoichi; Hayakawa, Shuhei; Honda, Ryotaro; Hosomi, Kenji; Imai, Kenichi; Ishimoto, Shigeru; Joo, Changwoo; Kanatsuki, Shunsuke; Kiuchi, Ryuta; Koike, Takeshi; Kumawat, Harphool; Matsumoto, Yuki; Miwa, Koji; Moritsu, Manabu; Naruki, Megumi; Niiyama, Masayuki; Nozawa, Yuki; Ota, Ryosuke; Sakaguchi, Atsushi; Sako, Hiroyuki; Samoilov, Valentin; Sato, Susumu; Shirotori, Kotaro; Sugimura, Hitoshi; Suzuki, Shoji; Takahashi, Toshiyuki; Takahashi, Tomonori; Tamura, Hirokazu; Tanaka, Toshiyuki; Tanida, Kiyoshi; Tokiyasu, Atsushi; Tsamalaidze, Zviadi; Roy, Bidyut; Ukai, Mifuyu; Yamamoto, Takeshi; Yang, Seongbae
Source
Subject
Language
Abstract
We have observed a "$K^-pp$"-like structure in the $d(\pi^+,K^+)$ reaction at 1.69 GeV/$c$. In this reaction $\Lambda(1405)$ hyperon resonance is expected to be produced as a doorway to form the $K^-pp$ through the $\Lambda^*p\rightarrow K^-pp$ process. However, most of the produced $\Lambda(1405)$'s would escape from deuteron without secondary reactions. Therefore, coincidence of high-momentum ($>$ 250~MeV/$c$) proton(s) in large emission angles ($39^\circ<\theta_{lab.}<122^\circ$) was requested to enhance the signal-to-background ratio. A broad enhancement in the proton coincidence spectra are observed around the missing-mass of 2.27 GeV/$c^2$, which corresponds to the $K^-pp$ binding energy of 95 $^{+18}_{-17}$ (stat.) $^{+30}_{-21}$ (syst.) MeV and the width of 162 $^{+87}_{-45}$ (stat.) $^{+66}_{-78}$ (syst.) MeV.
Comment: 8 pages, 4 figures, submitted to PTEP
Comment: 8 pages, 4 figures, submitted to PTEP