2003 Fiscal Year Annual Research Report

電子・陽子衝突による素粒子構造の研究の総括

Research Project

Project/Area Number	11206101
Research Institution	The High Energy Accelerator Research Organization
Principal Investigator	徳宿克夫高エネルギー加速器研究機構, 素粒子原子核研究所, 助教授 (80207547)
Co-Investigator(Kenkyū-buntansha)	山崎祐司高エネルギー加速器研究機構, 素粒子原子核研究所, 助手 (00311126) 栗原良将高エネルギー加速器研究機構, 素粒子原子核研究所, 助手 (50195559) 浜津良輔東京都立大学, 理学研究科, 助教授 (20087092) 山田作衛東京大学, 名誉教授
Keywords	電子・陽子衝突 / HERA / 弱い相互作用 / 偏極散乱 / 標準模型 / 陽子の構造 / 新粒子探索 / 回折反応
Research Abstract	ドイツ電子シンクロトロン研究所(DESY)の電子・陽子衝突型加速器HERAを用いて、レプトンとクォーク間の相互作用を精密に測定することが、この研究の目的である。測定に用いるZEUS実験装置は、我々を含む14カ国の国際共同実験グループで建設し、その後もさらなる改良を進めてきた。加速器の高輝度化改造の後、ビームと残留ガスとの反応によるバックグランドが非常に大きくなる問題が生じたが、これに対処するためにビーム衝突点付近の加速器改造を行い、10月より定常運転を始めた。実験条件は格段に良くなり問題点を解決できた。3月には瞬間衝突輝度(ルミノシティ)として、3×10^<31>cm^<-2>s^<-1>と改造前の2倍以上を達成し、今後さらに改良していく計画である。 27.5GeVの陽電子と920GeVの陽子の衝突で実験を進めているが、HERAの改造によって陽電子を縦偏極できるようになり、右巻き陽電子と陽子の偏極散乱を始めた。3月までに、平均偏極度33%で積算ルミノシティが約6.6pb^<-1>のデータが収集できた。この解析の結果、電磁相互作用が中心となる中性流反応では無偏極の断面積とよい一致を示したが、弱い相互作用のみで起こる荷電流反応では無偏極の場合より有意に断面積が大きくなっていることがわかり、3月末の国際会議で暫定結果を発表した。これは弱い相互作用が左巻き粒子(あるいは右巻き反粒子)間で起こることを電子・陽子衝突の荷電流反応において世界で初めて示したものである。今後さらにデータを蓄積することにより、標準模型の精密検証を進める。この偏極実験でのデータ収集と解析を最重要課題として進めたため、当初予定していたレビューとシンポジウムは、今年度内には行わないことにした。平成12年度までに収集した無偏極のデータをもとにした物理の解析は順調に進み、15編の論文を発表した。新粒子探索、陽子の構造、回折反応、粒子相関の研究に関してはほぼ解析を完了できたので、この部分の論文を集めた成果報告書を作成した。

Research Products

(17 results)

All Other

All Publications (17 results)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of proton-dissociative diffractive photoproduction of vector mesons at large momentum transfer at HERA"The European Physical Journal. C26. 389-409 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of high-Q^2 e-p neutral current cross sections at HERA and the extraction of xF_3"The European Physical Journal. C28. 175-201 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Leading proton production in e+p collisions at HERA"Nuclear Physics. B658. 3-46 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of event shapes in deep inelastic scattering at HERA"The European Physical Journal. C27. 531-545 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Scaling violations and determination of alpha_s from jet production in gamma p interactions at HERA"Physics Letters. B560. 7-23 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Search for single-top production in ep collisions at HERA"Physics Letters. B559. 153-170 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Dijet angular distributions in photoproduction of charm at HERA"Physics Letters. B565. 87-101 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "A search for resonance decays to lepton+jet at HERA and limits on leptoquarks"Physical Review. D68. 052004 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Jet production in charged current deep inelastic e+p scattering at HERA"The European Physical Journal. C31. 149-164 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of deeply virtual Compton scattering at HERA"Physics Letters. B573. 46-62 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of high-Q^2 charged current cross sections in e+p deep inelastic scattering at HERA"The European Physical Journal. C32. 1-16 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of the open-charm contribution to the diffractive proton structure function"Nuclear Physics. B672. 3-35 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Observation of K^0_sK^0_s resonances in deep inelastic scattering at HERA"Physics Letters. B578. 33-44 (2003)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of D^*± production in deep inelastic e±p scattering at HERA"Physical Review. D69. 012004 (2004)
[Publications] ZEUS Collaboration, S.Chekanov et al.: "Bose-Einstein correlations in one and two dimensions in deep inelastic scattering"Physics Letters. B583. 231-246 (2004)
[Publications] P.Karataev et al.: "Status of optical diffraction radiation experiment at KEK-ATF extraction line"Nuclear Instruments and Methods in Physics Research. B201. 140-152 (2003)
[Publications] G.Belanger et al.: "Full O(a) electroweak corrections to double Higgs-strahlung at the linear collider"Physics Letters. B576. 152-164 (2003)

2003 Fiscal Year Annual Research Report

電子・陽子衝突による素粒子構造の研究の総括

Principal Investigator

徳宿 克夫 高エネルギー加速器研究機構, 素粒子原子核研究所, 助教授 (80207547)

Research Products

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of proton-dissociative diffractive photoproduction of vector mesons at large momentum transfer at HERA"The European Physical Journal. C26. 389-409 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of high-Q^2 e-p neutral current cross sections at HERA and the extraction of xF_3"The European Physical Journal. C28. 175-201 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Leading proton production in e+p collisions at HERA"Nuclear Physics. B658. 3-46 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of event shapes in deep inelastic scattering at HERA"The European Physical Journal. C27. 531-545 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Scaling violations and determination of alpha_s from jet production in gamma p interactions at HERA"Physics Letters. B560. 7-23 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Search for single-top production in ep collisions at HERA"Physics Letters. B559. 153-170 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Dijet angular distributions in photoproduction of charm at HERA"Physics Letters. B565. 87-101 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "A search for resonance decays to lepton+jet at HERA and limits on leptoquarks"Physical Review. D68. 052004 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Jet production in charged current deep inelastic e+p scattering at HERA"The European Physical Journal. C31. 149-164 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of deeply virtual Compton scattering at HERA"Physics Letters. B573. 46-62 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of high-Q^2 charged current cross sections in e+p deep inelastic scattering at HERA"The European Physical Journal. C32. 1-16 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of the open-charm contribution to the diffractive proton structure function"Nuclear Physics. B672. 3-35 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Observation of K^0_sK^0_s resonances in deep inelastic scattering at HERA"Physics Letters. B578. 33-44 (2003)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Measurement of D^*± production in deep inelastic e±p scattering at HERA"Physical Review. D69. 012004 (2004)

[Publications] ZEUS Collaboration, S.Chekanov et al.: "Bose-Einstein correlations in one and two dimensions in deep inelastic scattering"Physics Letters. B583. 231-246 (2004)

[Publications] P.Karataev et al.: "Status of optical diffraction radiation experiment at KEK-ATF extraction line"Nuclear Instruments and Methods in Physics Research. B201. 140-152 (2003)

[Publications] G.Belanger et al.: "Full O(a) electroweak corrections to double Higgs-strahlung at the linear collider"Physics Letters. B576. 152-164 (2003)

徳宿克夫高エネルギー加速器研究機構, 素粒子原子核研究所, 助教授 (80207547)