1999 Fiscal Year Final Research Report Summary
Pion Production by Neutron Beam
| Project/Area Number |
10640271
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Fukui Medical University |
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Principal Investigator |
TAMURA Keisuke Fukui Medical University, Physics, Assistant Professor, 物理, 助教授 (30212046)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUOKA Nobuyuki Osaka University, RCNP, Assistant, 物理, 教授 (10030032)
OGAITO Tatoku Fukui Medical University, Physics, Assistant, 物理, 教授 (70291375)
YOKOO Yoshimatsu Fukui Medical University, Physics, Professor, 物理, 教授 (10028160)
SAGARA Takeshi Kyushu University, Dept. of Physics, Assistant Professor, 物理, 教授 (00128026)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Pion / Nucleon-Nucleon / Threshold |
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| Research Abstract |
The pion production pn → ppπィイD1-ィエD1 and pp → ppπィイD10ィエD1 were discussed. The theoretical analysis has been performed by using the models of heavy-meson exchange and pion-rescattering including the effect of nucleon resonances. For all the charge channels, the models work well from the near-threshold (s-wave amplitude) to the Δ energy region (p-wave amplitude). The pion-production cross sections are decomposed to four independent isospin amplitudes TィイD2IiIfィエD2 which represents the transition from an initial two nucleon state with isospin IィイD2iィエD2 to a final state with isospin IィイD2fィエD2. The reaction pp → ppπィイD10ィエD1 is characterized by the amplitude TィイD211ィエD2 which is mainly determined by the s-wave ィイD2πィエD2N interaction. Contrary to this, the reaction pn → ppπィイD1-ィエD1 depends on both the s-wave amplitude TィイD211ィエD2 and the p-wave amplitude TィイD201ィエD2. The interference between s- and p-wave causes the forward-backward asymmetry of the differential cross section. The recent works with the chiral perturbation theory predict the s-wave amplitude with the opposite sign to the results of the heavy-meson exchange model and the pion-rescattering model because the s-wave amplitude of the chiral perturbation theory changes its sign when going from on-shell to half-off-shell kinematics. However, the models with opposite sign of s-wave fail to explain the angular dependence of pn → ppπィイD1-ィエD1 reaction. We also discuss about following two topics about πィイD10ィエD1 production. 1) The angular distribution is very sensitive to the short range structure of Δ-excitation mechanism. 2) The measurement of analyzing power suggests that large s-wave amplitude is necessary even at higher energy region.
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