Diffractive D* production in deep inelastic ep scattering at HERA

A study of D*±(2010) mesons production in deep inelastic diffractive scattering at HERA using 43.0 pb-1 of data taken with the ZEUS detector is presented. Diffractive interactions in which the virtual photon dissociates into a hadronic system X and the proton remains intact or dissociates into a low mass state Y are identified by the presence of a large rapidity gap in the final state. D*s are reconstructed in the decay channel D*+ → (D0 → K-π+)πs+ + (c.c.). The accessible kinematic region for this measurement is 1 < Q2 < 400 GeV2, 0.02 < y < 0.7, 1.5 < pT(D*) < 8.0 GeV, vertical bar-η(D*)-vertical bar < 1.5, xP < 0.016 and β < 0.8, in which the cross section for diffractive D* production is measured to be 587 ± 88(stat) -135+211(syst) pb. The ratio of diffractive to total D* production in this region is also measured and found to be 6.2±1.0(stat) -1.4+1.4(syst) %, which is consistent with the fraction of diffractively produced events in inclusive deep inelastic scattering. Differential D* cross sections are also measured as a function of Q2, W, pT(D*), η(D*), xP and β and are compared to expectations from different theoretical models. The data clearly show that diffractive heavy flavour production is not suppressed relative to light flavours and favour a substantial hard gluon component in the diffractive exchange. Limited statistics and significant theoretical uncertainties prevent further discrimination between different theoretical models. (author)