Search for Pentaquark Θ + in Hadronic Reaction at J-PARC

Naruki, M.; Adachi, S.; Agnello, M.; Ajimura, S.; Aoki, K.; Bang, H.; Bassalleck, B.; Botta, Elena; Bufalino, S.; Ekawa, H.; Evtoukhovitch, P.; Feliciello, A.; Fujioka, H.; Hayakawa, S.; Hiruma, F.; Honda, R.; Hosomi, K.; Ichikawa, Y.; Ieiri, M.; Igarashi, Y.; Imai, K.; Ishibashi, N.; Ishimoto, S.; Itahashi, K.; Iwasaki, R.; Joo, G. G.; Kanatsuki, S.; Kim, M. J.; Kim, S. J.; Kiuchi, R.; Koike, T.; Komatsu, Y.; Kulikov, V. V.; Marcello, Simonetta; Masumoto, S.; Matsumoto, Y.; Matsuoka, K.; Miwa, K.; Moritsu, M.; Nagae, T.; Niiyama, M.; Noumi, H.; Nozawa, Y.; Ota, R.; Ozawa, K.; Saito, N.; Sakaguchi, A.; Sako, H.; Samoilov, V.; Sato, M.; Sato, S.; Sato, Y.; Sawada, S.; Sekimoto, M.; Shirotori, K.; Sugimura, H.; Suzuki, S.; Takahashi, T. N.; Takahashi, H.; Takahashi, T.; Tamura, H.; Tanaka, T.; Tanida, K.; Tokiyasu, A. O.; Tomida, N.; Tsamalaidze, Z.; Ukai, M.; Yagi, K.; Yamamoto, T. O.; Yang, S. B.; Yonemoto, Y.; Yoon, C. J.; Yoshida, K.

doi:10.1007/s00601-013-0685-2

The first experiment at the J-PARC hadron facility, the J-PARC E19 experiment, aims at searching 16 for the Θ + pentaquark in the hadronic reaction π − p → K − X using the missing-mass technique. Based on a superconducting magnet excited at 2.5 T, the spectrometer achieved the high mass resolution of 1.4 MeV/c2 for the Θ+ production process. The first data taking was performed in the autumn of 2010. No significant structure was observed in the missing-mass spectrum. The upper limit obtained for the differential cross section is 0.26 μb/sr in the laboratory frame at a 90 % CL.