Study of the Structure of the Photon in e-p Collision

电子-p碰撞中光子结构的研究

• 批准号: 06452027
• 负责人: YAMADA Sakue
• 金额: $ 3.33万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06452027/
• 关键词: electron-proton collision; photon structure functions; HERA; ZEUS; vector meson; resolved photon process; pomeron structure; 光子構造; ジェット現象; ベクトル粒子

We studied the structure of photon in electron-proton collisions at HERA by using a multi-purpose detector built in an international collaboration (ZEUS) at DESY in Germany The study is performed mainly in photoproduction processes where an electron emits an almost real photon that collides with a proton. The photon behaves like a hadron in the photoproduction process. In particular, the high-E_Tprocesses (hard photoproduction) are expected to be described by perturbative Quantum Chromodynamics (pQCD) as in the hadron-hadron collisions. The measurements of the jet and the heavy quark production provide a testing ground of pQCD.The structure of the photon can be investigated using the resolved processes where the photon is resolved into more than one parton. Photon-proton collisions also include diffractive processes where the photon dissociates into hadrons preserving its quantum numbers. The study of the diffractive process enables us to study the nature of the diffraction and the str … More ucture of the Pomeron, which is introduced in order to explain the cross section behavior of the hadron-hadron collisions.The measured cross sections of the jet production show good agreements with the prediction of pQCD.Those measurements imposed experimental restrictions on certain models based on pQCD, in particular on the structure of the photon. The measurement of the transverse momentum distribution of the photon remnant is consistent with the existence of the point-like coupling of the photon to a quark-pair, which is predicted by pQCD.The cross section of the charm quark production supports the model that allows a charm pair to be produced virtually inside the photon. The measurement also disclosed that the gluon density in the proton rapidly increases as it becomes soft.The large rapidity gap (LRG) in the produced hadrons is the characteristic property of the diffractive process. The behavior of LRG cross section showed that the diffractive process could be understood by the exchange of Pomeron. We measured the quark distribution of the Pomeron, and proved the existence of the gluon content in the Pomeron. Further, the evidence of the exchange of the Pomeron is found in the hard parton-parton collisions in photoproduction. The cross section of the vector meson production is explained by pQCD for the processes that involve a hard scale. Less

利用德国DESY国际合作项目（ZEUS）的多功能探测器，研究了HERA实验中电子-质子碰撞中的光子结构。研究主要在光生过程中进行，在光生过程中，电子发射出几乎真实的光子与质子碰撞。光子在光生过程中表现得像强子。特别地，高E_T过程（硬光生）可望象强子-强子碰撞那样用微扰量子色动力学（pQCD）来描述。喷注和重夸克产生的测量为pQCD提供了一个实验平台，光子的结构可以通过光子分解成多个部分子的分解过程来研究。光子-质子碰撞还包括衍射过程，其中光子解离成强子，保持其量子数。对衍射过程的研究使我们能够研究衍射的本质和应力 ...更多信息 Pomeron的结构，用来解释强子-强子碰撞的截面行为.喷注产生截面的测量结果与pQCD的预言符合得很好.这些测量结果对基于pQCD的某些模型，特别是对光子结构的实验限制.对光子残余物横向动量分布的测量结果与pQCD预言的光子与夸克对的点状耦合一致，而粲夸克产生的横截面则支持了在光子内部产生粲夸克对的理论.测量还揭示了质子中的胶子密度随其变软而迅速增加，产生的强子中的大快度能隙（LRG）是衍射过程的特征。LRG截面的行为表明，衍射过程可以用坡密子交换来理解。我们测量了Pomeron的夸克分布，证明了Pomeron中胶子含量的存在。此外，在光生过程中的部分子-部分子碰撞中发现了Pomeron交换的证据。矢量介子生产的横截面的pQCD解释的过程中，涉及到一个硬标度。少

项目成果

ZEUS Collaboration, M.Derrick et al.: "Measurement of charged and neutral current e-p deep inelastic scattering cross-sections at high Q^2" Phys.Rev.Lett.75. 1006-1011 (1995)

ZEUS Collaboration，M.Derrick 等人：“高 Q^2 处带电电流和中性电流 e-p 深非弹性散射截面的测量”Phys.Rev.Lett.75。

ZEUS Collaboration,M.Derrick et al.: "Rapidity Gaps between Jets in Photoproduction at HERA" Physics Letters. B369. 55-68 (1996)

ZEUS 合作，M.Derrick 等人：“HERA 摄影制作中喷气机之间的快速间隙”物理快报。

ZEUS Collaboration, M.Derrick et al.: "Study of D^* (2010) ^* production in ep collisions at HERA" Phys.Lett.B349. 225-237 (1995)

ZEUS 合作，M.Derrick 等人：“HERA ep 碰撞中 D^* (2010) ^* 产生的研究”Phys.Lett.B349。

ZEUS Collaboration,M.Derrick et al.: "Inclusive jet differential cross-sections in photoproduction at HERA" Physics Letters. B342. 417-432 (1995)

ZEUS 合作，M.Derrick 等人：“HERA 摄影制作中的包容射流微分横截面”《物理快报》。

ZEUS Collaboration,M.Derrick et al.: "Measurement of the cross-section for the reaction γ p -> J/Ψ p with the ZEUS detector at HERA" Physics Letters. B350. 120-134 (1995)

ZEUS Collaboration，M.Derrick 等人：“使用 HERA 的 ZEUS 探测器测量反应 γ p -> J/Ψ p 的横截面”《物理快报》120-134 (1995)。