Diffraction dissociation in photoproduction at HERA
Diffraction dissociation in photoproduction at HERA
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DOI：
10.1007/s002880050388
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发表时间：
1997-04-01
期刊：
影响因子：
--
通讯作者：
zurNedden, M
中科院分区：
文献类型：
--
作者：
Adloff, C;Aid, S;zurNedden, M
提出了对过程 gamma p --> XY 的研究，其中系统 X 和 Y 之间存在很大的速度差距。测量微分截面作为在光子顶点产生的系统的不变质量 M-x 的函数。结果显示在质心能量为 [W] = 187 G2V 和 [W] = 231 GeV 的地方，质子主要保持完整，并且首次解离。 HERA 数据和来自固定目标实验的质量中心能量和 M-x(2) 依赖性可以同时在三重 Regge 模型中描述。研究发现，低质量光子解离过程以衍射为主，尽管在较大质量下存在相当大的次主导贡献。提取波默子截距，发现为 alpha(p)(0) = 1.068 +/- 0.016（统计）+/- 0.022（系统）+/- 0.041（模型），与从总强子和弹性强子截面和光产生截面获得的值非常一致。在 M-x(2)/W-2 < 0.05 的情况下，对过程 gamma p --> Xp 的衍射贡献测量为 [W] = 187 GeV 处总 gamma p 横截面的 22.2 +/- 0.6（统计）+/- 2.6（系统）+/- 1.7（模型）%。
A study is presented of the process gamma p --> XY, where there is a large rapidity gap between the systems X and Y. Measurements are made of the differential cross section as a function of the invariant mass M-x of the system produced at the photon vertex. Results are presented at centre of mass energies of [W] = 187 G2V and [W] = 231 GeV, both where the proton dominantly remains intact and, for the first time, where it dissociates. Both the centre of mass energy and the M-x(2) dependence of HERA data and those from a fixed target experiment may simultaneously be described in a triple-Regge model. The low mass photon dissociation process is found to be dominated by diffraction, though a sizable subleading contribution is present at larger masses. The pomeron intercept is extracted and found to be alpha(p)(0) = 1.068 +/- 0.016 (stat.) +/- 0.022 (syst.) +/- 0.041 (model), in good agreement with values obtained from total and elastic hadronic and photoproduction cross sections. The diffractive contribution to the process gamma p --> Xp with M-x(2)/W-2 < 0.05 is measured to be 22.2 +/- 0.6 (stat.) +/- 2.6 (syst.) +/- 1.7 (model) % of the total gamma p cross section at [W] = 187 GeV.