| Submitted to (2007) | |||||||||||||
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| Parallel Session 6 www-h1.desy.de/h1/www/publications/conf/conf list.html Measurement of the Diffractive Deep-Inelastic Scattering Cross Section at Low Q H1 Collaboration Abstract A new measurement is presented of the diffractive deep-inelastic scattering process ep eXY , where Y is a proton or low mass excitation. The results are obtained from a data sample of 3.4 pb -1 taken by the H1 experiment at HERA, with unbiased triggers. The measurement is presented in the form of a 3-dimensional reduced cross section # , x IP ) which is integrated over the region M Y < 1.6 GeV and and covers the kinematic range 1.5 0.9 and 10 -4 x IP < 0.03. The results extend and improve the precision at the lowest Q considerably compared to previous measurements. Interpreted through Regge-motivated fits to the x IP dependence, the data suggest a lower value of the effective pomeron intercept than that obtained from higher Q data. The data are also compared with the predictions of a NLO DGLAP QCD fit to higher data. In the perturbative region Q > 3 GeV , the data confirm the dominance of a gluon distribution extending to large fractional momenta in the diffractive parton densities. | |||||||||||||
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