H1prelim-03-011

Measurement of the Diffractive Structure Function F_2^D(3) at high Q^2

Reference N.N., to be presented at DIS 2003, Spring 2003
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Contact P.Laycock, P.Newman
Abstract A new measurement of the diffractive structure function F_2^D(3)(xpom,x,Q^2) at high Q^2, describing the deep-inelastic scattering process ep->eXY in which the system Y is a proton or a low-mass proton excitation carrying a fraction 1-xpom of the beam longitudinal momentum, is presented in the kinematic range Q^2 > 130 GeV^2, 0.1 < beta=x/xpom < 0.9 and 10^-3 < xpom < 0.05. The data are used together with other recent measurements at small and intermediate Q^2 values to test various factorisation properties and models of diffractive DIS. The xpom dependence of F_2^D(3) is interpreted in terms of the effective pomeron intercept alpha_pom(0)(Q^2). The variation of F_2^D with x and Q^2 at fixed values of xpom is compared with the (x,Q^2) dependence of F_2(x,Q^2). Diffractive parton distributions are extracted from fits to the data based on the NLO DGLAP evolution equations and QCD hard scattering factorisation for semi-inclusive processes.
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