出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Open charm production in electron-proton (ep) scattering at the high energies of HERA (centreof-
mass energy √s ∼ 320 GeV) is an ideal tool to study perturbative Quantum Chromodynamics
(pQCD), since the charm mass provides a hard scale.
The main charm production mechanism is photon-gluon fusion (PGF) where a photon emitted by
the incoming electron interacts with a gluon in the proton forming a quark antiquark pair. The
cross section is dominated by processes where the virtuality Q2 of the exchanged photon is very
small. The kinematic region of Q2 < 1 GeV2 is generally referred to as photoproduction since
the photon is almost real. In this regime resolved photon processes in which the photon ¤uctuates
into a hadronic state before the hard interaction, become important.
Investigating £nal state correlations increases the sensitivity to the details of the charm production
mechanism. Here H1 and ZEUS measurements of D∗+jet cross sections in photoproduction are
presented. Comparing the pseudorapidity distributions of the D∗ and a jet not containing the D∗
reveals the presence of non-charm initiated jets. The difference in the azimuthal angle f between
the two highest pt jets shows the need for higher order contributions to describe the data.
Furthermore results from H1 investigations of the integrated jet shape in dijet events are shown,
where charm is tagged by a muon. The observations contradict the Monte Carlo expectation of
broad gluon initiated jets in a resolved enriched data sample.
