A test of the BFKL resummation at ILC

We consider the exclusive production of rho^0 meson pairs in gamma^*gamma^* scattering in the Regge limit of QCD as a probe of BFKL resummation effects and we show the feasibility of the measurement of this process at the ILC.Comment: To appear in the proceedings of the School on QCD, low-x physics, saturation and diffraction, Copanello Calabria, Italy, July 1-14 200

Production of rho meson pair in gamma* gamma* collisions

We have shown that the lowest order QCD amplitude, i.e. the quark exchange contribution, to the forward production of a pair of longitudinally polarized rmesons in the scattering of two virtual photons gamma (Q1) gamma (Q2) rho rho factorizes in two different ways: the part with transverse photons is described by the QCD factorization formula involving the generalized distribution amplitude of two final rho mesons, whereas the part with longitudinally polarized photons takes the QCD factorized form with the gamma rho transition distribution amplitude. Perturbative expressions forthese, in general, non-perturbative functions are obtained in terms of the rho meson distribution amplitude.Comment: International Workshop on Diffraction in High-Energy Physics -DIFFRACTION 2006 - September 5-10 2006 Adamantas, Milos island, Greec

On chiral-odd Generalized Parton Distributions

While the chiral-even content of the nucleon is better and better studied, the chiral-odd transversity generalized parton distributions (GPDs) remain almost unknown. These GPDs can be accessed experimentally through the exclusive photoproduction process gamma + N -> pi + rho + N', in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversally polarized state. We calculate perturbatively the scattering amplitude at leading order in alpha_s. We build a simple model for the dominant transversity GPD H_T(x,xi,t) based on the concept of double distribution. We estimate the unpolarized differential cross section for this process in the kinematics of the Jlab and COMPASS experiments. Counting rates show that the experiment looks feasible with the real and quasi real photon beam characteristics expected at JLab@12 GeV, and with the quasi real photon beam in the COMPASS experiment.Comment: 5 pages, to appear in the proceedings of 35th International Conference on High Energy Physics, (ICHEP 2010), Paris, France, July 22-28, 201

Chiral-odd transversity GPDs from a leading twist hard amplitude

The chiral-odd transversity generalized parton distributions (GPDs) of the nucleon can be accessed experimentally through the exclusive photoproduction process gamma + N -> pi + rho + N', in the kinematics where the meson pair has a large invariant mass and the final nucleon has a small transverse momentum, provided the vector meson is produced in a transversally polarized state. We calculate perturbatively the scattering amplitude at leading order in alpha_s. We build a simple model for the dominant transversity GPD H_T(x,xi,t) based on the concept of double distribution. We estimate the unpolarized differential cross section for this process in the kinematics of the Jlab and COMPASS experiments. Counting rates show that the experiment looks feasible with the real photon beam characteristics expected at JLab@12 GeV, and with the quasi real photon beam in the COMPASS experiment.Comment: 5 pages, to appear in the proceedings of 18th International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS 2010), Florence, Italy, 19-23 Apr 201

Studying QCD factorizations in exclusive gamma* gamma* -> rho^0_L rho^0_L

The exclusive process e+ e- -> e+ e- rho^0_L rho^0_L allows to study various dynamics and factorization properties of perturbative QCD. At moderate energy, we demonstrate how collinear QCD factorization emerges, involving generalized distribution amplitudes (GDA) and transition distribution amplitudes (TDA). At higher energies, in the Regge limit of QCD, we show that it offers a promising probe of the BFKL resummation effects to be studied at the International Linear Collider (ILC).Comment: invited talk presented at EDS07 11 figure

QCD factorizations in gamma* gamma* -> rho rho

We calculate the lowest order QCD amplitude, i.e. the quark exchange contribution, to the forward production amplitude of a pair of longitudinally polarized $\rho$ mesons in the scattering of two virtual photons $\gamma^*(Q_1) \gamma^*(Q_2) \to \rho^0_L \rho^0_L$. We show that the scattering amplitude simultaneously factorizes in two quite different ways: the part with transverse photons is described by the QCD factorization formula involving the generalized distribution amplitude of two final $\rho$ mesons, whereas the part with longitudinally polarized photons takes the QCD factorized form with the $\gamma^*_L \to \rho^0_L$ transition distribution amplitude. Perturbative expressions for these, in general, non-perturbative functions are obtained in terms of the $\rho-$meson distribution amplitude

Discovery of Novel Term Associations in a Document Collection

Non peer reviewe

Resummation of small x contributions to hard-scattering amplitudes

The summation of the small x corrections to hard scattering QCD amplitudes by collinear factorisation method is reconsidered and the K-factor is derived in leading log x approximation. The corresponding expression by Catani and Hautmann (1994) has to be corrected. The significance of the correction is demonstrated in the examples of structure function F_L and of exclusive electroproduction.Comment: 7 pages, 5 figures, talk given at the HS09 conferenc