Publications (26)
NLO Exclusive Evolution Kernels
A. V. Belitsky, A. Freund, D. Müller
We outline a formalism used for a construction of two-loop flavor singlet exclusive evolution kernels in the MS bar scheme. The approach is based on the known pattern of conformal…
NLO evolution kernels for skewed transversity distributions
A. V. Belitsky, A. Freund, D. Müller
We present a calculation of the two-loop evolution kernels of the twist-two transversally polarized quark and linearly polarized gluon skewed parton distributions in the minimal su…
Diffractive Exclusive Photon Production in DIS at HERA
L. Frankfurt, A. Freund, M. Strikman
We demonstrate that perturbative QCD allows one to calculate the absolute cross section of diffractive exclusive production of photons at large at HERA, while the aligned jet…
Geometric scaling in inclusive e A reactions and nonlinear perturbative QCD
A. Freund, K. Rummukainen, H. Weigert +1
In this note we report on geometric scaling in inclusive e A scattering data from the NMC and E665 experiments. We show that this scaling, as well as nuclear shadowing, is expected…
Coherent bremsstrahlung, coherent pair production, birefringence and polarimetry in the 20-170 GeV energy range using aligned crystals
NA59 Collaboration, A. Apyan, R. O. Avakian +27
The processes of coherent bremsstrahlung (CB) and coherent pair production (CPP) based on aligned crystal targets have been studied in the energy range 20-170 GeV. The experimental…
DVCS on nuclei: Observability and Consequences
A. Freund, M. Strikman
In this paper, we discuss the feasibility of measuring deeply virtual Compton scattering (DVCS) on nuclei in a collider setting, as for example, the planned high-luminosity Electro…
Deeply Virtual Compton Scattering at HERA - A Probe of Asymptotia
L. Frankfurt, A. Freund, M. Strikman
We demonstrate that the measurement of an azimuthal angle asymmetry in deeply virtual Compton scattering (DVCS) at HERA energies, is experimentally feasible and allows one to deter…
Single spin asymmetry in DVCS
A. Freund, M. Strikman
In the following note, we will present an estimation of the single spin asymmetry in deeply virtual Compton scattering (DVCS) which directly allows one to test predictions of the r…
Nuclear effects and their interplay in nuclear DVCS amplitudes
A. Freund, M. Strikman
In this paper we analyze nuclear medium effects on DVCS amplitudes in the $\Bx$ range of for a large range of and four different nuclei. We use our nucleon GPD m…
Exclusive annihilation p pbar -> gamma gamma in a generalized parton picture
A. Freund, A. V. Radyushkin, A. Schaefer +1
Exclusive proton-antiproton annihilation into two photons at large s (~10 GeV^2) and |t|,|u| ~ s can be described by a generalized parton picture analogous to the 'soft mechanism'…
Formation of Spiral Structures in Galactic Discs from Reaction-Diffusion Networks
A. Freund
In this paper, we propose an extension of the Smolin-model of a galactic disc in isolated, flocculent SC-type galaxies. This model supplies the necessary mechanism to suppress spat…
A next-to-leading order analysis of deeply virtual Compton scattering
A. Freund, M. F. McDermott
We present a complete, next-to-leading-order (NLO), leading-twist QCD analysis of deeply virtual Compton scattering (DVCS) observables, in the scheme, and in the kine…
Evolution kernels of skewed parton distributions: method and two-loop results
A. V. Belitsky, A. Freund, D. Müller
We present a formalism and explicit results for two-loop flavor singlet evolution kernels of skewed parton distributions in the minimal subtraction scheme. This approach avoids exp…
A detailed QCD analysis of twist-3 effects in DVCS observables
A. Freund
In this paper I present a detailed QCD analysis of twist-3 effects in the Wandzura-Wilczek (WW) approximation in deeply virtual Compton scattering (DVCS) observables for various ki…
Demystifying generalized parton distributions
A. Freund
In this paper, I will explain in as simple and intuitive physical terms as possible what generalized parton distributions are, what new information about the structure of hadrons t…
DVCS at HERA
L. Frankfurt, A. Freund, M. Strikman
We demonstrate that perturbative QCD allows one to calculate the absolute cross section of diffractive exclusive production of photons at large at HERA, while the aligned jet…
Next-to-leading order evolution of generalized parton distributions for HERA and HERMES
A. Freund, M. F. McDermott
The QCD evolution of both unpolarized and polarized generalized parton distributions (GPDs) to next-to-leading order (NLO) accuracy is presented, in both the DGLAP and ERBL regions…
Results on the Coherent Interaction of High Energy Electrons and Photons in Oriented Single Crystals
NA59 Collaboration, A. Apyan, R. O. Avakian +27
The CERN-NA-59 experiment examined a wide range of electromagnetic processes for multi-GeV electrons and photons interacting with oriented single crystals. The various types of cry…
Nondiagonal Parton Distributions in the Leading Logarithmic Approximation
L. L. Frankfurt, A. Freund, V. Guzey +1
In this paper we make predictions for nondiagonal parton distributions in a proton in the LLA. We calculate the DGLAP-type evolution kernels in the LLA, solve the nondiagonal GLAP…
Reconstruction of non-forward evolution kernels
A. V. Belitsky, D. Müller, A. Freund
We develop a framework for the reconstruction of the non-forward kernels which govern the evolution of twist-two distribution amplitudes and off-forward parton distributions beyond…
Measurement of Coherent Emission and Linear Polarization of Photons by Electrons in the Strong Fields of Aligned Crystals
NA59 Collaboration, A. Apyan, R. O. Avakian +27
We present new results regarding the features of high energy photon emission by an electron beam of 178 GeV penetrating a 1.5 cm thick single Si crystal aligned at the Strings-Of-S…
Density functional theory modeling of vortex shedding in superfluid He-4
A. Freund, D. Gonzalez, X. Buelna +2
Formation of vortex rings around moving spherical objects in superfluid He-4 at 0 K is modeled by time-dependent density functional theory. The simulations provide detailed informa…
Coherent Pair Production by Photons in the 20-170 GeV Energy Range Incident on Crystals and Birefringence
NA59 Collaboration, A. Apyan, R. O. Avakian +27
The cross section for coherent pair production by linearly polarised photons in the 20-170 GeV energy range was measured for photon aligned incidence on ultra-high quality diamond…
Linear to Circular Polarisation Conversion using Birefringent Properties of Aligned Crystals for Multi-GeV Photons
NA59 Collaboration, A. Apyan, R. O. Avakian +27
We present the first experimental results on the use of a thick aligned Si crystal acting as a quarter wave plate to induce a degree of circular polarisation in a high energy linea…
A next-to-leading order QCD analysis of deeply virtual Compton scattering amplitudes
A. Freund, M. F. McDermott
We present a next-to-leading order (NLO) QCD analysis of unpolarized and polarized deeply virtual Compton scattering (DVCS) amplitudes, for two different input scenarios, in the $\…
Modelling generalized parton distributions to describe deeply virtual Compton scattering data
A. Freund, M. McDermott, M. Strikman
We present a new model for generalized parton distributions (GPDs), based on the aligned jet model, which successfully describes the deeply virtual Compton scattering (DVCS) data f…