The relevance of ${\mathbf{\gamma^*_{\mathrm{L}}}}$ in hard collisions of virtual photons

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 .…”

QCD improved parton distribution functions of

“…The contributions of γ * L plotted in Figs. 2 and 3 of [6] and reproduced by dashed curves in Figs. 5 below were calculated using simple QED formula (13) for the quark content of γ * L .…”

“…In [6] we discussed the numerical relevance of the contribution of resolved γ * L for two physical quantities: F γ 2 (x, P 2 , M 2 ) and the effective PDF…”

Partonic structure of the virtual photon

“…The main argument for adding O(α 3 s ) resolved photon terms to O(αα 2 s ) direct and O(α 2 s ) resolved photon contributions is based on specific way factorization mechanism works for processes involving initial photons. This point is crucial but subtler and we therefore merely summarize the conclusions and refer the reader to [3,7], for details. In fact one can look at O(α 3 s ) resolved photon terms as results of approximate evaluation of the so far uncalculated O(αα 3 s ) direct photon diagrams in the collinear kinematics.…”