Charm production in deep inelastic and diffractive scattering

Abstract

We consider the production of charm by real and virtual photons. Special attention is paid to diffractive charm production, which provides information on the gluonic content of the Pomeron. Our calculations are based on the gluon distributions of the CKMT-model, which is shown to lead to agreement with the data on open charm production in deep inelastic scattering. We compare predictions for diffractive charm production of different models for the distribution of gluons in the Pomeron. Experiments at HERA should be able to discriminate between them. Predictions for beauty production in diffractive and non-diffractive interactions of photons are also given.

Measurement of diffractive production of D∗±(2010) mesons in deep-inelastic scattering at HERA

“…Both inclusive and diffractive DIS cross sections rise more rapidly with energy than is the case for soft hadronic interactions [8], indicating the presence of a hard process to which perturbative Quantum Chromodynamics (pQCD) is applicable. Charm production is a key process for investigating the dynamics of diffractive DIS [9][10][11][12][13][14], since the charm-quark mass provides a hard scale and charm production is known to be sensitive to gluon-exchange processes in DIS [15,16].…”

Charm production in diffractive deep inelastic scattering

“…In Ref. [11], where charm diffractive production was computed, n g takes values between 0 and -1 in order to produce a normalizable distribution, which implies for n g < 0 a singular behavior also at β = 1. As a good description of the Q 2 dependence of the HERA data is achieved with n g = 0 and in view that a singular behavior for large β is not observed in Regge-like fitting procedures to DDIS data, we assume this value in our analyzes.…”

“…Similarly, the study of the diffractive final state can lead to further progress in the direction of obtaining a coherent picture of the diffraction. In particular, charm production looks promising in this respect, as predictions for this process widely differ among several models [7,8,9,10,11]. Recently, the ZEUS collaboration has presented its results for the measurement of the open-charm contribution to the diffractive proton structure function [12].…”

On the behavior of $F_2$ and its logarithmic slopes

“…Eq. (29) is valid below the charm threshold [11,12], i.e. Q 2 0 < Q 2 < Q 2 c , and in the high Q 2 -region where the charm can be considered as a "massless" dynamical quark [12].…”

“…(29) is valid below the charm threshold [11,12], i.e. Q 2 0 < Q 2 < Q 2 c , and in the high Q 2 -region where the charm can be considered as a "massless" dynamical quark [12]. As described above, the charm is treated via a photon-gluon fusion process in the range Q 2 c < Q 2 <Q 2 = 50 GeV 2 [11,12].…”