Diffractive Photoproduction of D*+/-(2010) at HERA

TL;DR

This study measures diffractive D* meson photoproduction at HERA, finding that about 6% of inclusive D* production is diffractive, with results aligning with perturbative QCD predictions and supporting diffractive factorisation.

Contribution

First measurement of diffractive D* meson photoproduction at HERA confirming QCD factorisation in diffraction.

Findings

Diffractive contribution to D* production is approximately 6%.

Data agree with perturbative QCD models using diffractive PDFs.

Results support the validity of diffractive QCD factorisation.

Abstract

Diffractive photoproduction of D*+/-(2010) mesons was measured with the ZEUS detector at the ep collider HERA, using an integrated luminosity of 78.6 pb^{-1}. The D* mesons were reconstructed in the kinematic range: transverse momentum p_T(D*) > 1.9 GeV and pseudorapidity |eta(D*)| < 1.6, using the decay D*+ -> D0 pi+_s followed by D0 -> K- pi+ (+c.c.). Diffractive events were identified by a large gap in pseudorapidity between the produced hadronic state and the outgoing proton. Cross sections are reported for photon-proton centre-of-mass energies in the range 130 < W < 300 GeV and for photon virtualities Q^2 < 1 GeV^2, in two ranges of the Pomeron fractional momentum x_pom < 0.035 and x_pom < 0.01. The relative contribution of diffractive events to the inclusive D*+/-(2010) photoproduction cross section is about 6%. The data are in agreement with perturbative QCD calculations based on various parameterisations of diffractive parton distribution functions. The results are consistent with diffractive QCD factorisation.