# Measurement and QCD Analysis of the Diffractive Deep-Inelastic Scattering Cross Section at HERA

Abstract : A detailed analysis is presented of the diffractive deep-inelastic scattering process $ep\to eXY$, where $Y$ is a proton or a low mass proton excitation carrying a fraction $1 - \xpom > 0.95$ of the incident proton longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfies $|t|<1 {\rm GeV^2}$. Using data taken by the H1 experiment, the cross section is measured for photon virtualities in the range $3.5 \leq Q^2 \leq 1600 \rm GeV^2$, triple differentially in $\xpom$, $Q^2$ and $\beta = x / \xpom$, where $x$ is the Bjorken scaling variable. At low $\xpom$, the data are consistent with a factorisable $\xpom$ dependence, which can be described by the exchange of an effective pomeron trajectory with intercept $\alphapom(0)= 1.118 \pm 0.008 {\rm (exp.)} ^{+0.029}_{-0.010} {\rm (model)}$. Diffractive parton distribution functions and their uncertainties are determined from a next-to-leading order DGLAP QCD analysis of the $Q^2$ and $\beta$ dependences of the cross section. The resulting gluon distribution carries an integrated fraction of around 70% of the exchanged momentum in the $Q^2$ range studied. Total and differential cross sections are also measured for the diffractive charged current process $e^+ p \to \bar{\nu}_e XY$ and are found to be well described by predictions based on the diffractive parton distributions. The ratio of the diffractive to the inclusive neutral current $ep$ cross sections is studied. Over most of the kinematic range, this ratio shows no significant dependence on $Q^2$ at fixed $\xpom$ and $x$ or on $x$ at fixed $Q^2$ and $\beta$.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00079770
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Submitted on : Monday, January 8, 2007 - 10:32:10 AM
Last modification on : Sunday, June 26, 2022 - 11:45:55 AM

### Citation

A. Aktas, V. Andreev, T. Anthonis, S. Aplin, A. Asmone, et al.. Measurement and QCD Analysis of the Diffractive Deep-Inelastic Scattering Cross Section at HERA. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2006, 48, pp.715-748. ⟨10.1140/epjc/s10052-006-0035-3⟩. ⟨in2p3-00079770⟩

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