D*± meson production in deep-inelastic diffractive interactions at HERA

A measurement is presented of the cross section for D*+/- meson production in diffractive deep-inelastic scattering for the first time at HERA. The cross section is given for the process ep --> eXY, where the system X contains at least one D*+/- meson and is separated by a large rapidity gap from a low mass proton remnant system Y. The cross section is presented in the diffractive deep-inelastic region defined by 2 <Q(2) <100 GeV2, 0.05 <y <0.7, x(P) <0.04, M-Y <1.6 GeV and \t \ <1 GeV2. The D*+/- mesons are restricted to the range P-T,P-D* > 2 GeV and \ eta (D*)\ <1.5. The cross section is found to be 246 +/- 54 +/- 56 ph and forms about 6% of the corresponding inclusive D*+/- cross section. The cross section is presented as a function of various kinematic variables, including z(P)(obs) which is an estimate of the fraction of the momentum of the diffractive exchange carried by the parton entering the hard-subprocess. The data show a large component of the cross section at low Z(obs)(P) where the contribution of the boson-gluon-fusion process is expected to dominate. The data are compared with several QCD-based calculations. (C) 2001 Elsevier Science B.V. All rights reserved.