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arXiv 1107.3420hep-ex
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HERA衍射纵向结构函数F_L^D的测量

Measurement of the Diffractive Longitudinal Structure Function F_L^D at HERA

H1 Collaboration

摘要:

第一次测量的衍射截面$σ_{ep \rightarrow eXY}$在质心能量$\sqrt{s}$的225和252 GeV,连同一个精确的新的测量在$\sqrt{s}$的319 GeV,使用的数据与H1探测器在2006年和2007年。结合先前在301 GeV的$\sqrt{s}$上的H1数据,测量被用来提取在光子虚值4.0 <= Q^2 <= 44.0 GeV^2和质子纵向动量损失分数5 10^{-4} <= x_{IP} <= 3 10^{-3}范围内的衍射纵向结构函数F_L^D。测量的F_L^D与领先的扭曲预测的基础上提取的衍射部分子密度在NLO QCD适合以前的测量衍射深度非弹性散射和模型,其中还包括一个更高的扭曲贡献来自一个颜色偶极子的方法。提取了由纵向偏振光子引起的衍射截面与横向偏振光子引起的衍射断面之比,并与包含深度非弹性散射的类似量进行了比较。

英文摘要:

First measurements are presented of the diffractive cross section $σ_{ep \rightarrow eXY}$ at centre-of-mass energies $\sqrt{s}$ of 225 and 252 GeV, together with a precise new measurement at $\sqrt{s}$ of 319 GeV, using data taken with the H1 detector in the years 2006 and 2007. Together with previous H1 data at $\sqrt{s}$ of 301 GeV, the measurements are used to extract the diffractive longitudinal structure function F_L^D in the range of photon virtualities 4.0 <= Q^2 <= 44.0 GeV^2 and fractional proton longitudinal momentum loss 5 10^{-4} <= x_{IP} <= 3 10^{-3}. The measured F_L^D is compared with leading twist predictions based on diffractive parton densities extracted in NLO QCD fits to previous measurements of diffractive Deep-Inelastic Scattering and with a model which additionally includes a higher twist contribution derived from a colour dipole approach. The ratio of the diffractive cross section induced by longitudinally polarised photons to that for transversely polarised photons is extracted and compared with the analogous quantity for inclusive Deep-Inelastic Scattering.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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