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Start Over Author "Tokiyasu, A." Journal physical review letters
9 results on '"Tokiyasu, A."'

1. Search for η′ Bound Nuclei in the C12(γ,p) Reaction with Simultaneous Detection of Decay Products

Author

Hajime Shimizu, Y. Yanai, H. Ikuno, J. Y. Chen, W. C. Chang, T. Shibukawa, H. Ohnishi, J. M. Jo, K. Mizutani, M. L. Chu, Yorihito Sugaya, Norihito Muramatsu, Tomoaki Hotta, Y. Kon, Y. Sada, K. Shiraishi, T. Hashimoto, Tetsuhiko Yorita, I. Jaegle, H. Katsuragawa, Yuji Nozawa, T. Nakano, Yoji Ohashi, Shinichi Masumoto, T. Ishikawa, Y. Matsumura, M. Sumihama, A. O. Tokiyasu, T. Ohta, Tomoyuki Maruyama, R. Yamazaki, T. Nam, M. Yosoi, Kyoichiro Ozawa, Q. H. He, H. Hamano, Toshiyuki Gogami, J. K. Ahn, S. Daté, R. Shirai, Manabu Miyabe, Hideko Nagahiro, K. Hicks, N. Tomida, Yuki Honda, T. Ueda, S. Kido, Leps, C. Yoshida, S. Y. Ryu, M. Sasagawa, Satoshi Tanaka, E. A. Strokovsky, H. Yamazaki, Y. Tsuchikawa, Toshihiko Hiraiwa, M. Niiyama, Y. Inoue, Chary Rangacharyulu, Y. Kasamatsu, H. Goto, T. N. T. Ngan, T. Nakamura, and S. Suzuki

Subjects
Physics, Crystallography, medicine.anatomical_structure, Branching fraction, 0103 physical sciences, Mass spectrum, medicine, General Physics and Astronomy, 010306 general physics, 01 natural sciences, Nucleus, Coincidence, Production rate
Abstract

We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}N→ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ_{lab}^{ηp}

Published
2020
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2. Search for η^{'} Bound Nuclei in the ^{12}C(γ,p) Reaction with Simultaneous Detection of Decay Products

Author

N, Tomida, N, Muramatsu, M, Niiyama, J K, Ahn, W C, Chang, J Y, Chen, M L, Chu, S, Daté, T, Gogami, H, Goto, H, Hamano, T, Hashimoto, Q H, He, K, Hicks, T, Hiraiwa, Y, Honda, T, Hotta, H, Ikuno, Y, Inoue, T, Ishikawa, I, Jaegle, J M, Jo, Y, Kasamatsu, H, Katsuragawa, S, Kido, Y, Kon, T, Maruyama, S, Masumoto, Y, Matsumura, M, Miyabe, K, Mizutani, H, Nagahiro, T, Nakamura, T, Nakano, T, Nam, T N T, Ngan, Y, Nozawa, Y, Ohashi, H, Ohnishi, T, Ohta, K, Ozawa, C, Rangacharyulu, S Y, Ryu, Y, Sada, M, Sasagawa, T, Shibukawa, H, Shimizu, R, Shirai, K, Shiraishi, E A, Strokovsky, Y, Sugaya, M, Sumihama, S, Suzuki, S, Tanaka, A, Tokiyasu, Y, Tsuchikawa, T, Ueda, H, Yamazaki, R, Yamazaki, Y, Yanai, T, Yorita, C, Yoshida, and M, Yosoi

Abstract

We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}N→ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ_{lab}^{ηp}-0.9 was obtained to be 2.2 nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η^{'} production rate. Our results indicate a small branching fraction of the η^{'}N→ηN process and/or a shallow η^{'}-nucleus potential.

Published
2020

3. Interference Effect betweenϕandΛ(1520)Production Channels in theγp→K+K−pReaction near Threshold

Author

J. Y. Chen, Y. Nakatsugawa, S. i. Nam, R. G. T. Zegers, Jung Keun Ahn, P. M. Shagin, M. Fujiwara, Takashi Ohta, Y. Toi, Tetsuhiko Yorita, H. Kohri, Yoshikazu Maeda, E. A. Strokovsky, K. Kino, S. Hasegawa, M. Miyachi, C. W. Wang, T. Matsuda, S. Daté, Yuhei Morino, S. Ajimura, T. Ishikawa, M. Sumihama, T. Ooba, S. Fukui, M. Uchida, S. C. Wang, J. Parker, Tomoaki Hotta, Takahiro Iwata, S. Makino, R. Murayama, A. O. Tokiyasu, K. Hicks, Haruo Ohkuma, N. Kumagai, A. Wakai, Y. Shiino, W. C. Chang, Masaharu Nomachi, H. Ejiri, T. Nakano, Masato Yoshimura, Hidetoshi Akimune, S. Y. Ryu, K. Horie, Hiroyuki Toyokawa, P. J. Lin, Yuji Ohashi, D. S. Ahn, T. Sawada, Chary Rangacharyulu, H. Fujimura, K. Yonehara, H. Kawai, Y. Asano, Hajime Shimizu, D. S. Oshuev, T. Tsunemi, Kenichi Imai, Y. Kato, S. H. Hwang, N. Matsuoka, Atsushi Sakaguchi, Yorihito Sugaya, Norihito Muramatsu, M. Ungaro, M. Yosoi, Y. Kon, Tsutomu Mibe, Manabu Miyabe, and M. Niiyama

Subjects
Physics, Particle physics, 010308 nuclear & particles physics, Hyperon, General Physics and Astronomy, State (functional analysis), Lambda, 01 natural sciences, Pentaquark, Pomeron, 0103 physical sciences, Production (computer science), Atomic physics, Proton emission, Nuclear Experiment, 010306 general physics, Energy (signal processing)
Abstract

The $\ensuremath{\phi}\text{\ensuremath{-}}\mathrm{\ensuremath{\Lambda}}(1520)$ interference effect in the $\ensuremath{\gamma}p\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}p$ reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between $\ensuremath{\phi}$ and $\mathrm{\ensuremath{\Lambda}}(1520)$ production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when ${K}^{+}{K}^{\ensuremath{-}}$ pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the $\sqrt{s}=2.1\text{ }\text{ }\mathrm{GeV}$ bump structure in forward differential cross sections for $\ensuremath{\phi}$ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.

Published
2016
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4. Interference Effect between ϕ and Λ(1520) Production Channels in the γp→K^{+}K^{-}p Reaction near Threshold

Author

S Y, Ryu, J K, Ahn, T, Nakano, D S, Ahn, S, Ajimura, H, Akimune, Y, Asano, W C, Chang, J Y, Chen, S, Daté, H, Ejiri, H, Fujimura, M, Fujiwara, S, Fukui, S, Hasegawa, K, Hicks, K, Horie, T, Hotta, S H, Hwang, K, Imai, T, Ishikawa, T, Iwata, Y, Kato, H, Kawai, K, Kino, H, Kohri, Y, Kon, N, Kumagai, P J, Lin, Y, Maeda, S, Makino, T, Matsuda, N, Matsuoka, T, Mibe, M, Miyabe, M, Miyachi, Y, Morino, N, Muramatsu, R, Murayama, Y, Nakatsugawa, S I, Nam, M, Niiyama, M, Nomachi, Y, Ohashi, H, Ohkuma, T, Ohta, T, Ooba, D S, Oshuev, J D, Parker, C, Rangacharyulu, A, Sakaguchi, T, Sawada, P M, Shagin, Y, Shiino, H, Shimizu, E A, Strokovsky, Y, Sugaya, M, Sumihama, A O, Tokiyasu, Y, Toi, H, Toyokawa, T, Tsunemi, M, Uchida, M, Ungaro, A, Wakai, C W, Wang, S C, Wang, K, Yonehara, T, Yorita, M, Yoshimura, M, Yosoi, and R G T, Zegers

Abstract

The ϕ-Λ(1520) interference effect in the γp→K^{+}K^{-}p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between ϕ and Λ(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K^{+}K^{-} pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the sqrt[s]=2.1 GeV bump structure in forward differential cross sections for ϕ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.

Published
2016

5. Search for theΘ+Pentaquark via theπ−p→K−XReaction at1.92 GeV/c

Author

M. Niiyama, S. Marcello, A. O. Tokiyasu, Sung Jae Kim, K. Itahashi, R. Kiuchi, Koji Miwa, Mitsuhiro Sato, Takahiro Tanaka, Alessandro Feliciello, Ryotaro Honda, M. Moritsu, Masaharu Ieiri, V. Samoilov, S. Sawada, Nobuyuki Chiga, Michelangelo Agnello, Y. Yonemoto, Kanae Aoki, N. Ishibashi, N. Tomida, S. Ishimoto, Susumu Sato, Petr Evtoukhovitch, Tadayuki Takahashi, R. Iwasaki, Takeshi Koike, Hitoshi Sugimura, Y. Igarashi, F. Hiruma, K. Matsuoka, K. Shirotori, Megumi Naruki, Yoichi Sato, K. Yagi, Kiyoshi Tanida, Tomofumi Nagae, T. Takahashi, Elena Botta, H. C. Bhang, S. Y. Suzuki, S. Bufalino, Kyoichiro Ozawa, S. B. Yang, H. Fujioka, Yudai Ichikawa, K. Yoshida, Minu Kim, V. V. Kulikov, Kenichi Imai, Shunsuke Adachi, Atsushi Sakaguchi, Mifuyu Ukai, Z. Tsamalaidze, M. Sekimoto, Hiroyuki Sako, Y. Komatsu, C. J. Yoon, S. Ajimura, Hitoshi Takahashi, Tokujiro Yamamoto, C. W. Joo, Hirokazu Tamura, B. Bassalleck, N. Saito, Shinichi Masumoto, K. Hosomi, and Hiroyuki Noumi

Subjects
Physics, Baryon, Particle physics, Meson, Scattering, Effective lagrangian, General Physics and Astronomy, Production (computer science), Pentaquark
Abstract

The ${\ensuremath{\Theta}}^{+}$ pentaquark baryon was searched for via the ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}{K}^{\ensuremath{-}}X$ reaction with a missing mass resolution of $1.4\text{ }\text{ }\mathrm{MeV}/{c}^{2}$ (FWHM) at the Japan Proton Accelerator Research Complex (J-PARC). ${\ensuremath{\pi}}^{\ensuremath{-}}$ meson beams were incident on the liquid hydrogen target with a beam momentum of $1.92\text{ }\text{ }\mathrm{GeV}/c$. No peak structure corresponding to the ${\ensuremath{\Theta}}^{+}$ mass was observed. The upper limit of the production cross section averaged over the scattering angle of 2\ifmmode^\circ\else\textdegree\fi{} to 15\ifmmode^\circ\else\textdegree\fi{} in the laboratory frame is obtained to be $0.26\text{ }\text{ }\ensuremath{\mu}\mathrm{b}/\mathrm{sr}$ in the mass region of $1.51--1.55\text{ }\text{ }\mathrm{GeV}/{c}^{2}$. The upper limit of the ${\ensuremath{\Theta}}^{+}$ decay width is obtained to be 0.72 and 3.1 MeV for ${J}_{\ensuremath{\Theta}}^{P}=1/{2}^{+}$ and ${J}_{\ensuremath{\Theta}}^{P}=1/{2}^{\ensuremath{-}}$, respectively, using the effective Lagrangian approach.

Published
2012
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6. Search for theΘ+Pentaquark via theπ−p→K−XReaction at1.92GeV/c

Author

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

Published
2012
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7. Search for η^{'} Bound Nuclei in the ^{12}C(γ,p) Reaction with Simultaneous Detection of Decay Products.

Author

Tomida N, Muramatsu N, Niiyama M, Ahn JK, Chang WC, Chen JY, Chu ML, Daté S, Gogami T, Goto H, Hamano H, Hashimoto T, He QH, Hicks K, Hiraiwa T, Honda Y, Hotta T, Ikuno H, Inoue Y, Ishikawa T, Jaegle I, Jo JM, Kasamatsu Y, Katsuragawa H, Kido S, Kon Y, Maruyama T, Masumoto S, Matsumura Y, Miyabe M, Mizutani K, Nagahiro H, Nakamura T, Nakano T, Nam T, Ngan TNT, Nozawa Y, Ohashi Y, Ohnishi H, Ohta T, Ozawa K, Rangacharyulu C, Ryu SY, Sada Y, Sasagawa M, Shibukawa T, Shimizu H, Shirai R, Shiraishi K, Strokovsky EA, Sugaya Y, Sumihama M, Suzuki S, Tanaka S, Tokiyasu A, Tsuchikawa Y, Ueda T, Yamazaki H, Yamazaki R, Yanai Y, Yorita T, Yoshida C, and Yosoi M

Abstract

We measured missing mass spectrum of the ^{12}C(γ,p) reaction for the first time in coincidence with potential decay products from η^{'} bound nuclei. We tagged an (η+p) pair associated with the η^{'}N→ηN process in a nucleus. After applying kinematical selections to reduce backgrounds, no signal events were observed in the bound-state region. An upper limit of the signal cross section in the opening angle cosθ&#95;{lab}^{ηp}<-0.9 was obtained to be 2.2  nb/sr at the 90% confidence level. It is compared with theoretical cross sections, whose normalization ambiguity is suppressed by measuring a quasifree η^{'} production rate. Our results indicate a small branching fraction of the η^{'}N→ηN process and/or a shallow η^{'}-nucleus potential.

Published
2020
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8. Interference Effect between ϕ and Λ(1520) Production Channels in the γp→K^{+}K^{-}p Reaction near Threshold.

Author

Ryu SY, Ahn JK, Nakano T, Ahn DS, Ajimura S, Akimune H, Asano Y, Chang WC, Chen JY, Daté S, Ejiri H, Fujimura H, Fujiwara M, Fukui S, Hasegawa S, Hicks K, Horie K, Hotta T, Hwang SH, Imai K, Ishikawa T, Iwata T, Kato Y, Kawai H, Kino K, Kohri H, Kon Y, Kumagai N, Lin PJ, Maeda Y, Makino S, Matsuda T, Matsuoka N, Mibe T, Miyabe M, Miyachi M, Morino Y, Muramatsu N, Murayama R, Nakatsugawa Y, Nam SI, Niiyama M, Nomachi M, Ohashi Y, Ohkuma H, Ohta T, Ooba T, Oshuev DS, Parker JD, Rangacharyulu C, Sakaguchi A, Sawada T, Shagin PM, Shiino Y, Shimizu H, Strokovsky EA, Sugaya Y, Sumihama M, Tokiyasu AO, Toi Y, Toyokawa H, Tsunemi T, Uchida M, Ungaro M, Wakai A, Wang CW, Wang SC, Yonehara K, Yorita T, Yoshimura M, Yosoi M, and Zegers RG

Abstract

The ϕ-Λ(1520) interference effect in the γp→K^{+}K^{-}p reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between ϕ and Λ(1520) production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when K^{+}K^{-} pairs are observed at forward angles but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the sqrt[s]=2.1  GeV bump structure in forward differential cross sections for ϕ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange, or rescattering processes via other hyperon states.

Published
2016
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9. Search for the Θ+ pentaquark via the π(-)p→K(-)X reaction at 1.92 GeV/c.

Author

Shirotori K, Takahashi TN, Adachi S, Agnello M, Ajimura S, Aoki K, Bhang HC, Bassalleck B, Botta E, Bufalino S, Chiga N, Evtoukhovitch P, Feliciello A, Fujioka H, Hiruma F, Honda R, Hosomi K, Ichikawa Y, Ieiri M, Igarashi Y, Imai K, Ishibashi N, Ishimoto S, Itahashi K, Iwasaki R, Joo CW, Kim MJ, Kim SJ, Kiuchi R, Koike T, Komatsu Y, Kulikov VV, Marcello S, Masumoto S, Matsuoka K, Miwa K, Moritsu M, Nagae T, Naruki M, Niiyama M, Noumi H, Ozawa K, Saito N, Sakaguchi A, Sako H, Samoilov V, Sato M, Sato S, Sato Y, Sawada S, Sekimoto M, Sugimura H, Suzuki S, Takahashi H, Takahashi T, Tamura H, Tanaka T, Tanida K, Tokiyasu AO, Tomida N, Tsamalaidze Z, Ukai M, Yagi K, Yamamoto TO, Yang SB, Yonemoto Y, Yoon CJ, and Yoshida K

Abstract

The Θ(+) pentaquark baryon was searched for via the π(-)p→K(-)X reaction with a missing mass resolution of 1.4 MeV/c(2) (FWHM) at the Japan Proton Accelerator Research Complex (J-PARC). π(-) meson beams were incident on the liquid hydrogen target with a beam momentum of 1.92 GeV/c. No peak structure corresponding to the Θ(+) mass was observed. The upper limit of the production cross section averaged over the scattering angle of 2° to 15° in the laboratory frame is obtained to be 0.26 μb/sr in the mass region of 1.51-1.55 GeV/c(2). The upper limit of the Θ(+) decay width is obtained to be 0.72 and 3.1 MeV for J(Θ)(P)=1/2(+) and J(Θ)(P)=1/2(-), respectively, using the effective Lagrangian approach.

Published
2012
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