2002 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)	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, 大学院・理学研究科, 助教授 (20087092) 山田作衛高エネルギー加速器研究機構, 素粒子原子核研究所, 所長 (70011658) 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)
Keywords	電子・陽子衝突 / HERA / 陽子の構造 / 量子色力学 / クォーク / グルーオン
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の精密測定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、改良を進めている。加速器の高輝度化改造が完了し、4月より陽電子・陽子衝突を始めたが、バックグランドが多く実験不能の事態が生じた。加速器と実験グループの共同作業で原因の究明にかかり、陽電子からの放射光が多重反射していることが主な原因であることがわかった。このため衝突地点付近のビームライン改造が必要となり、平成15年3月から4ヶ月にわたって実験を中断し改造を行う事となった。今年度の実験はこの調査に時間がかかったのと、低いビーム電流でしか実験ができなかったことで、積算ルミノシティは約1pb^<-1>と予定の0.5%しか得られなかった。このため後半に予定していた研究会の企画は延期した。しかしこのデータは、我々が新しく設置した高精度シリコン飛跡検出器の性能検査、および新しいトリガーシステム、偏極測定装置の調整には十分な量になり、それぞれ設計通りの動作を確認できた。また2月には電子の縦偏極のテストを行い、即座に50%以上の偏極度を達成できたので、改造以後速やかに高輝度偏極実験を始められると期待している。平成12年度までに収集したデータをもとにした物理の解析は順調に進み、17編の論文を発表した。主な成果としては、測定した深非弾性散乱反応の断面積のデータと標準模型との比較から、陽子構造を探り、内部クォーク・グルーオンの分布を精度よく定めたことが上げられる。低い運動量を担うグルーオン分布のQ^2依存性を精度よく求めた。この解析や、多重ジェット生成事象を通して、強い相互作用の結合定数をそれぞれ独立に精度よく求めることができ、普遍性を示した。理論研究班は、量子色力学の高次の効果を含めた事象生成プログラムの開発が進んだ。

Research Products

(22 results)

All Other

All Publications (22 results)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Dijet production in neutral current deep inelastic scattering at HERA"The European Physical Journal. C23. 13-27 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Searches for excited fermions in ep collisions at HERA"Physics Letters. B549. 32-47 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of the photon-proton total cross section at a center-of-mass energy of 209 Ge V at HERA"Nuclear Physics. B627. 3-28 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "High-mass dijet cross sections in photoproduction at HERA"Physics Letters. B531. 9-27 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Dijet photoproduction at HERA and the structure of the photon"The European Physical Journal. C23. 615-631 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Search for lepton-flavor violation in e^+p collisions at HERA"Physical Review. D65. 092004 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Exclusive photoproduction of J/Psi mesons at HERA"The European Physical Journal. C25. 345-360 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of the Q^2 and energy dependence of diffractive interactions at HERA"The European Physical Journal. C25. 169-187 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Leading Neutron production in e^+p collisions at HERA"Nuclear Physics. B637. 3-56 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of high-Q^2 charged current cross sections in ep deep inelastic scattering at HERA"Physics Letters. B539. 197-217 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of diffractive production of D^<*±>(2010) mesons in deep inelastic scattering at HERA"Physics Letters. B545. 244-260 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "A ZEUS next-to-leading-order QCD analysis of data on deep inelastic scattering"Physical Review. D67. 012007 (2003)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Inclusive jet cross sections in the Breit frame in neutral current deep inelastic scattering at HERA and determination of α_s"Physics Letters. B547. 164-180 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurements of inelastic J/psi and J/psi' photoproduction at HERA"The European Physical Journal. C27. 173-188 (2002)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Study of the azimuthal asymmetry of jets in neutral current deep inelastic scattering at HERA"Physics Letters. B551. 226-240 (2003)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Observation of the strange sea in the proton via inclusive φ-meson production in neutral current deep inelastic scattering at HERA"Physics Letters. B553. 141-158 (2003)
[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of subjet multiplicities in neutral current deep inelastic scattering at HERA and determination of αs"Physics Letters. B558. 41-58 (2003)
[Publications] H.Okuno et al.: "Experimental study of positron production from a W single crystal by the KEK 8-GeV electron linac beam"Nuclear Instruments and Methods in Physics Research. B201. 259-265 (2003)
[Publications] T.Suwada et al.: "Measurement of positron production efficiency from a tungsten mono-crystalline target using 4 and 8 GeV electrons"Physical Review. E67. 016502 (2003)
[Publications] T.Muto et al.: "Observation of incoherent diffraction radiation from a single edge target in the visible light region"Physical Review Letters. 90. 104801 (2003)
[Publications] Y.Kurihara et al.: "QCD event generators with next-to-leading order matrix-elements and parton showers"Nuclear Physics. B654. 301-319 (2003)
[Publications] S.Tsuno et al.: "GR@PPA_4b : A four bottom quark production event generator for pp/ppbar collisions"Computer Physics Communications. 151. 216-240 (2003)

2002 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.: "Dijet production in neutral current deep inelastic scattering at HERA"The European Physical Journal. C23. 13-27 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Searches for excited fermions in ep collisions at HERA"Physics Letters. B549. 32-47 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of the photon-proton total cross section at a center-of-mass energy of 209 Ge V at HERA"Nuclear Physics. B627. 3-28 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "High-mass dijet cross sections in photoproduction at HERA"Physics Letters. B531. 9-27 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Dijet photoproduction at HERA and the structure of the photon"The European Physical Journal. C23. 615-631 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Search for lepton-flavor violation in e^+p collisions at HERA"Physical Review. D65. 092004 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Exclusive photoproduction of J/Psi mesons at HERA"The European Physical Journal. C25. 345-360 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of the Q^2 and energy dependence of diffractive interactions at HERA"The European Physical Journal. C25. 169-187 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Leading Neutron production in e^+p collisions at HERA"Nuclear Physics. B637. 3-56 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of high-Q^2 charged current cross sections in ep deep inelastic scattering at HERA"Physics Letters. B539. 197-217 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of diffractive production of D^<*±>(2010) mesons in deep inelastic scattering at HERA"Physics Letters. B545. 244-260 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "A ZEUS next-to-leading-order QCD analysis of data on deep inelastic scattering"Physical Review. D67. 012007 (2003)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Inclusive jet cross sections in the Breit frame in neutral current deep inelastic scattering at HERA and determination of α_s"Physics Letters. B547. 164-180 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurements of inelastic J/psi and J/psi' photoproduction at HERA"The European Physical Journal. C27. 173-188 (2002)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Study of the azimuthal asymmetry of jets in neutral current deep inelastic scattering at HERA"Physics Letters. B551. 226-240 (2003)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Observation of the strange sea in the proton via inclusive φ-meson production in neutral current deep inelastic scattering at HERA"Physics Letters. B553. 141-158 (2003)

[Publications] ZEUS Collaboration, S. Chekanov et al.: "Measurement of subjet multiplicities in neutral current deep inelastic scattering at HERA and determination of αs"Physics Letters. B558. 41-58 (2003)

[Publications] H.Okuno et al.: "Experimental study of positron production from a W single crystal by the KEK 8-GeV electron linac beam"Nuclear Instruments and Methods in Physics Research. B201. 259-265 (2003)

[Publications] T.Suwada et al.: "Measurement of positron production efficiency from a tungsten mono-crystalline target using 4 and 8 GeV electrons"Physical Review. E67. 016502 (2003)

[Publications] T.Muto et al.: "Observation of incoherent diffraction radiation from a single edge target in the visible light region"Physical Review Letters. 90. 104801 (2003)

[Publications] Y.Kurihara et al.: "QCD event generators with next-to-leading order matrix-elements and parton showers"Nuclear Physics. B654. 301-319 (2003)

[Publications] S.Tsuno et al.: "GR@PPA_4b : A four bottom quark production event generator for pp/ppbar collisions"Computer Physics Communications. 151. 216-240 (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)