Search for the pentaquark at J-PARC

Moritsu, M.; Adachi, S.; Agnello, M.; Ajimura, S.; Aoki, K.; Bhang, H. C.; Bassalleck, B.; Botta, Elena; Bufalino, S.; Chiga, N.; 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, C. W.; 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.; Nagae, T.; Naruki, M.; 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, H.; Takahashi, T.; Takahashi, T. N.; 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:10.1016/j.nuclphysa.2013.01.010

We have been searching for the Θ+ pentaquark via the π−p → K−X reaction at the J-PARC hadron facility. No peak structure was observed in the missing mass spectrum obtained at 1.92 GeV/c beam mo- mentum. The upper limit for the production cross section averaged over the scattering angle from 2◦ to 15◦ in the laboratory frame was derived to be 0.26 μb/sr. In order to make a more stringent constraint we have also performed a measurement at 2.0 GeV/c. Present analysis status of this new data is reported.