Yang, S. B.Tanida, K.Ahn, J. K.Adachi, I.Aihara, H.Asner, D. M.Atmacan, H.Aulchenko, V.Aushev, T.Ayad, R.Babu, V.Behera, P.Belous, K.Bennett, J.Bessner, M.Bhardwaj, V.Bhuyan, B.Bodrov, D.Borah, J.Bozek, A.Branchini, P.Browder, T. E.Budano, A.Campajola, M.Cervenkov, D.Chang, M. -C.Chang, P.Cheon, B. G.Chilikin, K.Cho, E.Cho, K.Cho, S. -J.Choi, S. -K.Choi, Y.Choudhury, S.Cinabro, D.Das, S.De Pietro, G.Dhamija, R.Di Capua, F.Dolezal, Z.Dong, T.Dossett, D.Epifanov, D.Fulsom, B. G.Garg, R.Gaur, V.Garmash, A.Giri, A.Goldenzweig, P.Graziani, E.Gu, T.Guan, Y.Gudkova, K.Hadjivasiliou, C.Hayasaka, K.Hayashii, H.Hou, W. -S.Hsu, C. -L.Iijima, T.Inami, K.Ipsita, N.Ishikawa, A.Itoh, R.Iwasaki, M.Iwasaki, Y.Jacobs, W. W.Jang, E. -J.Ji, Q. P.Jia, S.Jin, Y.Joo, K. K.Kang, K. H.Karyan, G.Kawasaki, T.Kichimi, H.Kiesling, C.Kim, C. H.Kim, D. Y.Kim, K. -H.Kim, Y. J.Kim, Y. -K.Kindo, H.Kodys, P.Konno, T.Korobov, A.Korpar, S.Kovalenko, E.Krizan, P.Krokovny, P.Kumar, M.Kumar, R.Kumara, K.Kwon, Y. -J.Lam, T.Lange, J. S.Laurenza, M.Lee, J. Y.Lee, S. C.Li, C. H.Li, J.Li, L. K.Li, Y.Gioi, L. LiLibby, J.Lieret, K.Liventsev, D.Luo, T.Masuda, M.Matsuda, T.Matvienko, D.Maurya, S. K.Meier, F.Merola, M.Metzner, F.Miyabayashi, K.Mizuk, R.Mohanty, G. B.Nakamura, I.Nakano, T.Nakao, M.Natkaniec, Z.Natochii, A.Nayak, L.Niiyama, M.Nisar, N. K.Nishida, S.Ono, H.Oskin, P.Pakhlov, P.Pakhlova, G.Pardi, S.Park, H.Park, S. -H.Passeri, A.Patra, S.Paul, S.Pedlar, T. K.Pestotnik, R.Piilonen, Leo E.Podobnik, T.Prencipe, E.Prim, M. T.Rout, N.Russo, G.Sandilya, S.Santelj, L.Savinov, V.Schnell, G.Schueler, J.Schwanda, C.Seino, Y.Senyo, K.Sevior, M. E.Shapkin, M.Sharma, C.Shen, C. P.Shiu, J. -G.Singh, J. B.Sokolov, A.Solovieva, E.Staric, M.Sumihama, M.Sumiyoshi, T.Sutcliffe, W.Takizawa, M.Tamponi, U.Tenchini, F.Trabelsi, K.Tsuboyama, T.Uchida, M.Uglov, T.Unno, Y.Uno, S.Ushiroda, Y.Usov, Y.van Tonder, R.Varner, G.Vossen, A.Waheed, E.Wang, E.Wang, M. -Z.Wang, X. L.Watanabe, M.Watanuki, S.Werbycka, O.Won, E.Yabsley, B. D.Yan, W.Yelton, J.Yin, J. H.Yuan, C. Z.Yusa, Y.Zhai, Y.Zhang, Z. P.Zhilich, V.Zhukova, V.2023-12-082023-12-082023-08-162023-08-162470-0010https://hdl.handle.net/10919/117142We observe a narrow peaking structure in the pK- invariant-mass spectrum near the Λη threshold. The peak is clearly seen in 1.5 million events of Λc+→pK-π+ decay using the 980 fb-1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e- collider. We try two approaches to explain this structure: as a new resonance and as a cusp at the Λη threshold. The best fit is obtained with a coherent sum of a Flatté function and a constant background amplitude with the reduced χ2 of 257/243 (p=0.25), while the fits to Breit-Wigner functions are unfavored by more than 7σ. The best fit explains the structure as a cusp at the Λη threshold, and the obtained parameters are consistent with the known properties of Λ(1670). The observation gives the first identification of a threshold cusp in hadrons from the spectrum shape.6 page(s)application/pdfenIn CopyrightScience & TechnologyPhysical SciencesAstronomy & AstrophysicsPhysics, Particles & FieldsPhysics5106 Nuclear and Plasma Physics5107 Particle and High Energy Physics51 Physical SciencesArticle - Refereedhttps://doi.org/10.1103/PhysRevD.108.L0311041083Piilonen, Leo [0000-0001-6836-0748]2470-0029