Prompt photon photoproduction at DESY HERA in thekT-factorization approach

Abstract

We present calculations of the prompt photon photoproduction at HERA collider in the k T -factorization approach. Both direct and resolved contributions are taken into account. The conservative error analisys is performed. The unintegrated parton densities in a proton and in a photon are determined using the Kimber-Martin-Ryskin prescription. We investigate both inclusive and associated with jet prompt photon photoproduction rates. In particular, we study the angular correlations between produced photon and hadronic jet in the transverse momentum plane which can provide a unique information about non-collinear evolution dynamics. We compare our theoretical predictions with recent experimental data taken by the H1 and ZEUS collaborations.

Dijet correlations at BNL RHIC: Leading-orderkt-factorization approach versus next-to-leading order collinear approach

“…The k t -factorization was originally proposed for heavy quark production [4]. In recent years it was used to describe several high-energy processes, such as total cross section in virtual photon -proton scattering [5], heavy quark inclusive production [6,7], heavy quark -heavy antiquark correlations [8,9], inclusive photon production [10,11], inclusive pion production [14,15], Higgs boson [12] or gauge boson [13] production and dijet correlations in photoproduction [16] and hadroproduction [17].…”

Deep inelastic beauty production at HERA in thekT-factorization approach

“…We can conclude that in the small x region (x < 10 −2 ) the shape of function F b 2 (x, Q 2 ) predicted by the unintegrated gluon distributions under consideration is very different. In particular, the differences observed between the curves are due to the different behaviour of the corresponding unintegrated gluon distributions as a function of x and k 2 T [45]. This fact shows the importance of a detail understanding of the non-collinear parton evolution in a proton and the necessarity of better experimental constraints as well as further theoretical studies in this field.…”

“…Based on this point, in our further calculations we use much more simpler DGLAP equation up to the last evolution step 4 . Note that the KMR parton densities in a proton were used, in particular, to describe the prompt photon photoproduction at HERA [45] and prompt photon hadroproduction Tevatron [46,47].…”

Further studies of the photoproduction of isolated photons with a jet at HERA

“…The cross sections for isolated-photon production in photoproduction have been calculated to nextto-leading order (NLO) by Fontannaz, Guillet and Heinrich (FGH) [13][14][15]. Calculations based on the k T -factorisation approach have been made by Lipatov, Malyshev and Zotov (LMZ) [16][17][18][19].…”

“…The k T -factorisation method used by LMZ [16][17][18] makes use of unintegrated parton densities in the proton, using the KMR formalism [37,38] based on the MSTW08 proton parton densities [39]. In addition to the hard QCD subprocess, the model incorporates a parton evolution cascade, one jet from which can be taken as the leading jet in the analysis.…”