2004 Fiscal Year Final Research Report Summary
Study of kaon decays using stopped positive kaons at the KEK proton synchrotron
| Project/Area Number |
14540285
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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 | High Energy Accelerator Research Organization (2004)
The High Energy Accelerator Research Organization (2002-2003) |
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Principal Investigator |
IMAZATO Jun Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Professor, 素粒子原子核研究所, 教授 (40107686)
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| Co-Investigator(Kenkyū-buntansha) |
SAWADA Shinya High Energy Accelerator Research Organization (KEK), Institute of Particle and Nuclear Studies, Research Associate, 素粒子原子核研究所, 助手 (70311123)
IGARASHI Youichi High Energy Accelerator Research Organization (KEK), Institute of Particle and Nuclear Studies, Research Associate, 素粒子原子核研究所, 助手 (50311121)
ASANO Yuzo University of Tsukuba, Faculty of Physical Engineering, Professor, 物理工学系, 教授 (80100808)
SHIMIZU Suguru Osaka University, Faculty of Science, Research Associate, 理学系, 助手 (60294146)
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| Project Period (FY) |
2002 – 2004
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| Keywords | T violation / CP violation / New physics search / Kaon decays / Kμ3 decay / Transverse polarization / K^+→π^0π^+γ decay direct emission / J-PARC |
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| Research Abstract |
In this research program two experiments of E246 'Search for T-violating transverse muon polarization' and E470 "Branching ratio measurement of K^+ → π^0π^+γ decay direct emission" were performed at the KEK proton synchrotron. The transverse polarization, P_T, which is T-odd in nature, is an important quantity related to CP violation. Since there is no contribution to PT from the standard model, It is a very sensitive probe of new physics beyond the standard model. In the present work careful data analysis was performed for the data which had already been taken by 2000 and systematic error were thoroughly studied. A final result of transverse polarization and its physics parameter Imξ were obtained as P_T = -0.0017 ±0.0023 (stat) ±0.0011 (syst), and Imξ = -0.0055 ±0.0071 (stat) ±0.0036 (syst), which were consistent with zero revealing no T violation. In the E470 experiment the direct emission component of K^+ →π^0π^+γ which is a chiral anomaly transition was extracted in a precise spec
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tral measurement. From about 4,000 extracted events, the branching ratio was determined to be BR(DE) = (6.1±2.5(stat) ±1.9(syst))X10^<-3> which was consistent with the recent BNL result but contradicting previous in-flight decay data. As a byproduct the K^+→π^0π^0e^+ν decay was studied, and from exracted 216 events a form factor was determined although the statistical accuracy was still not good, and formalism was established to deduce the π-π scattering length.
The possibilities of kaon decay experiments to use stopped K^+ beam at J-PARC, now under construction, were investigated. Since one expects 100 times higher beam intensity there, not only quantitative but also qualitative improvements and developments of data will be pursued. Regarding the T-violation muon polarization experiment, it will become important to measure not only the K^+ →π^0μ^+ν decay but also the K^+→μ^+νγ decay, which are complementary in some theoretical models of CP violation. New detector systems were investigated and several decay channels were studied with their physics cases. Less
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