Related papers: Two-Photon Exclusive Processes in QCD
Presented are recent results of two-photon interactions. Topics inlcude photon structure functions, inclusive hadron production, differential cross sections derived from tagged 2-photon fusion events and results in exclusive hadron…
We discuss diffractive photon-production of vector mesons in holographic QCD. At large $\sqrt{s}$, the QCD scattering amplitudes are reduced to the scattering of pair of dipoles exchanging a closed string or a pomeron. We use the…
Using the high energy color dipole approach, we study the exclusive photoproduction of lepton pairs. We use simple models for the elementary dipole-hadron scattering amplitude that captures main features of the dependence on atomic number…
I present a definition of the cross section for the production of an isolated photon plus $n$ jets which only depends upon direct photon production, and it is independent of the parton-to-photon fragmentation contribution. This…
We investigate the exclusive photoproduction of a heavy timelike photon which decays into a lepton pair, gamma p -> l+ l- p. This can be seen as the analog of deeply virtual Compton scattering, and we argue that the two processes are…
Direct (prompt) photon production is a field of very high interest in hadron colliders. It provides probes to search for new phenomena and to test QCD predictions. In this article, two recent cross-section results for direct photon…
The presence of two photon exchange in $ep$ elastic scattering and in the crossed processes ($\bar p +p\leftrightarrow \ell^+ +\ell^-$, $\ell=e$ or $\mu$) is discussed in terms of three complex amplitudes which are functions of two…
We calculate the production of high energy photons from Compton and annihilation processes as well as fragmentation off quarks in the parton cascade model. The multiple scattering of partons is seen to lead to a substantial production of…
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer $Q^2$. It is shown that the leading two-photon exchange amplitude behaves as $1/Q^4$ relative to the one-photon amplitude, and…
We perform detailed calculations of two-photon-exchange QED corrections to the cross section of pion electroproduction. The results are obtained with and without the soft-photon approximation; analytic expressions for the radiative…
The hadroproduction of lepton pairs with mass $Q$ and transverse momentum $Q_T$ can be described in perturbative QCD by the same partonic subprocesses as prompt photon production. We demonstrate that, like prompt photon production, lepton…
The reactions gamma p -> K+ Lambda and gamma p -> K* Lambda are analyzed within perturbative QCD, allowing for diquarks as quasi-elementary constituents of baryons. The diquark-model parameters and the quark-diquark distribution amplitudes…
Exclusive vector meson production and deeply virtual Compton scattering are ideally suited reactions for studying the structure of the proton and the transition from soft to hard processes. The main experimental data obtained at HERA are…
We describe a new way to access the chiral odd transversity parton distribution in the proton through the photoproduction of lepton pairs. The basic ingredient is the interference of the usual Bethe Heitler or Drell-Yan amplitudes with the…
It is generally assumed that due to factorization of long- and short-distance dynamics perturbative QCD can be applied to exclusive hadronic reactions at large momentum transfers. Within such a perturbative approach diquarks turn out to be…
We give predictions for the leading order amplitudes for deeply virtual Compton scattering and hard meson electroproduction reactions at large Q^2 in the valence region in terms of skewed quark distributions. We give first estimates for the…
We develop a consistent technique for the calculation of real photon emission in hard exclusive processes, which is based on the background field formalism and allows a convenient separation of hard electromagnetic and soft hadronic…
A new model of QCD parton shower is proposed which is dedicated to two-photon process in $e^+ e^-$ scattering. When hadron jets are produced, the photon may resolve into quark-antiquark pairs so that the structure functions of the photon…
Some non linear, second order QED processes in the presence of intense plane electromagnetic waves are investigated. Analytic expressions with general kinematics are derived for Compton scattering and $e^+e^-$ pair production in a…
We present QCD results for the exclusive processes $\gamma{\rm N}\rightarrow\gamma{\rm N}$ ($\rm N=p,\;n$) at large momentum transfer and compare them to data for the proton. TALK given at DPF meeting, November 10-14, Fermilab.