Interpreting virtual photon interactions in terms of parton distribution functions

Abstract

Interactions of virtual photons are analyzed in terms of photon structure. It is argued that the concept of parton distribution functions is phenomenologically very useful even for highly virtual photons involved in hard collisions. The role of longitudinal photons for proper interpretation of jet cross-sections in the region of moderate virtualities accessible at HERA is investigated.

Electroproduction cross section of large-E $_{\bot}$ hadrons at NLOand virtual photon structure function

“…Since then several papers have been published discussing the parton distributions in virtual photons at the LL approximation [26,27,28] and NLO approximation [29,30,31], and emphasizing the possibility to measure them in electroproduction experiments [13,14,32,33,34,35,36]. In this section we present a study of the parton distributions in virtual photons performed in the MS scheme, using the results of section 3 on the inputs at K 2 = Q 2 .…”

Partonic structure of γ[sub L][sup ∗] in hard collisions

“…Although this distinction between the content of PDF of real and virtual photons exists, it does not affect the phenomenological usefulness of PDF of the virtual photon. As shown in [5] the nontrivial part of the contributions of resolved γ…”

Resolved $\gamma^*_L$ in hard collisions of virtual photons: QCD effects

“…The condition P 2 ≪ M 2 guarantees clear physical meaning of the resulting quark and gluon distribution functions. Moreover, by staying away from the 3 The parameterization of PDF of γ * L can be obtained from chyla@fzu.cz. region P 2 ∼ M 2 we avoid the region where power corrections of the type P 2 /M 2 are essential and, in fact, more important than the effects described by PDF.…”

“…Let us briefly recall the virtue of extending the concept of partonic "structure" to virtual photons [3,5]:…”

“…Although this distinction between the content of PDF of real and virtual photons exists, it does not affect the extraordinary phenomenological usefulness of PDF of the virtual photon. As shown in [3] the nontrivial part of the contributions of resolved transverse virtual photon (γ * T ) to NLO calculations of dijet production at HERA is large and affects significantly the conclusions of phenomenological analyses of existing experimental data.…”