| Project/Area Number |
11694101
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | High Energy Accelerator Research Organization |
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Principal Investigator |
IMAZATO Jun KEK, IPNS, High Energy Accelerator Research Organization, Professor, 素粒子原子核研究所, 教授 (40107686)
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| Co-Investigator(Kenkyū-buntansha) |
IGARASHI Yoichi KEK, IPNS, High Energy Accelerator Research Organization, Assistant, 素粒子原子核研究所, 助手 (50311121)
AOKI Masaharu Osaka Univ., Associate Professor, 理, 助教授 (80290849)
KUNO Yoshitaka Osaka Univ., Professor, 理, 教授 (30170020)
ASANO Yuzo Univ. of Tsukuba, Professor (80100808)
G. Y Lim (GEI Youb lim) 高エネルギー加速器研究機構, 素粒子原子核研究所, 助手 (90332113)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1999: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Kaon decay / K_<μ3> decay / Muon transverse polarization / Time reversal inveriance / Toroidal spectrometer / KEK-PS / 対称性の破れ / CP対称性の破れ / Kμ3崩壊 / 形状因子 / Ke3崩壊 / K^+→π^+π^0γ崩壊 / ミュンン偏極 / 横偏極 / K_<e3>崩壊 / KEK陽子加速器 / CP不変性の破れ / ミュオン偏極 / K_<π3>崩壊 |
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| Research Abstract |
The research consisted of the KEK-PS experiments E246 and E470. The E246 experiment was searching for T-violating muon polarization (P_γ) in K^+→π^0μ^+νdecay (K_<μ3> using the superconducting toroidal spectrometer setup in conjunction with a stopped K^+ beam. It was aimed to carry out a measurement with small systematic errors. We performed data taking in 1999 and 2000 using 1600 hours of beam time. In 2001 we continued data analysis and obtained a result of P_T= -0.0033±0.0117(stat)±0.003(syst) combined with our previous result and reported in a conference. The systematic errors of the 1998 results were further studied carefully. The data from the 1999 and 2000 runs were also analyzed and a preliminary result of P_T was obtained.
One of the byproduct physics from this stopped K^+ experiment is the branching ratio measurement of the direct emission in K^+→π^+π^0γ decay. For an optimized trigger condition run, a new experiment was approved as E470 and it ran in the fall of 2001 for 960 hours. The data taking was successful and the branching ratio of the order of magnitude of 10^<-5> is expected to be determined with an accuracy of about 10 %. As another byproduct channel of E246, K^+→π^0e^+νdecay (K_<e3> was studied further to constrain the exotic scalar and tensor couplings. The values of f_R/f_+(0)=0.0040±0.0160(stat)±0.0067(syst) and f_T/f_+(0)=0.019±0.080(stat)±0.038(syst) were obtained. The decay width ratio of the two channels, Γ(K_<e3>)/Γ(K_<μ3>), was also analyzed and determined the q^2-dependent coefficient of f_0 form factor of the K_</3> decay to be λ_0 =0.019±0.005(stat)±0.004 (syst).
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