相关论文: DVCS amplitude at tree level: Transversality, twis…

We present a systematic study of twist-3 light-cone distribution amplitudes of vector mesons in QCD, which is based on conformal expansion. A complete set of distribution amplitudes is constructed for \rho, \omega, K^* and \phi mesons,…

We discuss the determination of deep-inelastic hadron structure in lattice QCD. By using a fictitious heavy quark, direct calculations of the Compton scattering tensor can be performed in Euclidean space that allow the extraction of the…

We argue that due to Parity constraints, the helicity combination of the purely momentum space counterparts of the Wigner distributions -- the generalized transverse momentum distributions -- that describes the configuration of an…

Virtual Compton Scattering (VCS) at low transferred momenta to the proton ($t$) and sufficiently high c.m. energies ($s$) may be used to a) study $Q^2$--dependence of leading $t$--channel exchanges and b) look for onset of scaling behavior…

We perform a study of the doubly virtual Compton scattering off a spinless target gamma* P -> gamma* P' within the Anti-de Sitter(AdS)/QCD formalism. We find that the general structure allowed by the Lorentz invariance and gauge invariance…

The spin-4/3 fractional superstring is characterized by a world-sheet chiral algebra involving spin-4/3 currents. The discussion of the tree-level scattering amplitudes of this theory presented in hepth/9310131 is expanded to include…

We calculate spin, charge, and azimuthal asymmetries in deeply virtual Compton scattering at leading twist-two level. The measurement of these asymmetries gives an access to the imaginary and real part of all deeply virtual Compton…

An overview of the current status of and possible future theoretical, phenomenological and experimental studies of DVCS and SPD's is presented.

We discuss the pion and kaon distribution amplitudes up to twist-3 in the context of the random instanton vacuum (RIV). We construct explicitly the pertinent quasi-pion and quasi-kaon distributions in the RIV, and analyze them in leading…

We study analytical properties of the hard exclusive processes amplitudes. We found that QCD factorization for deeply virtual Compton scattering and hard exclusive vector meson production results in the subtracted dispersion relation with…

We consider, in a string theory framework, physical processes of phenomenological interest in models with a low string scale. The amplitudes we study involve tree-level virtual gravitational exchange, divergent in a field-theoretical…

Spin and transverse momentum dependent parton distributions - Generalized Parton Distributions (GPDs) - are at the interface between the QCD structure of the hadrons and observable quantities. The GPDs are linear superpositions within…

Tree-level scattering amplitudes for a scalar particle coupled to an arbitrary number N of photons and a single graviton are computed. We employ the worldline formalism as the main tool to compute the irreducible part of the amplitude,…

Certain scattering amplitudes in the gravitational sector of type II string theory on K3 x T^2 are found to be computed by correlation functions of the N=4 topological string. This analysis extends the already known results for K3 by…

We present a completely gauge-invariant operator definition of transverse-momentum-dependent parton densities (TMD), supplied with longitudinal lightlike gauge links as well as transverse gauge links at lightcone infinity. Within this…

We computed the NLO corrections to twist-3, $L \to T$, flavor non-singlet amplitude in DVCS on a nucleon in the Wandzura-Wilczek approximation. Explicit calculation shows that factorization holds for NLO contribution to this amplitude,…

Timelike Compton scattering (TCS) i.e. the exclusive photoproduction of a lepton pair with large invariant mass nicely complements the already successful experimental study of deeply virtual Compton scattering (DVCS). The same Generalized…

The decomposition of nonlocal operators (and of their matrix elements) into an (infinite) series w.r.t. geometric twist is used to introduce (new) parton distributions, generalized parton distributions and hadron wave functions of definite…

The positivity bounds on generalized parton distributions are derived from the positivity properties of the absorptive part of the amplitude of the virtual Compton scattering in the generalized Bjorken region.

We discuss the low-energy behavior of the virtual Compton scattering amplitude off a spin-zero target. We first compare various methods of obtaining a low-energy expression based either on the soft-photon approximation or the use of…