Related papers: gamma* -> rhoT impact factor with twist three accu…
We show that electromagnetic gauge invariance requires a 'spin rotation' of the quarks in the usual twist-2 contribution to the amplitude for deeply virtual Compton scattering. This rotation is equivalent to the inclusion of certain…
We present the complete results up to twist-3 for hadron production in the target fragmentation region of semi-inclusive deep inelastic scattering with a polarized lepton beam and polarized nucleon target. The nonperturbative effects are…
Gravitational Compton scattering process with a massive fermion is studied in the context of the linearized gravity. Gravitational gauge invariance and graviton transversality cause the transition amplitude to be factorized into that of…
The transition form factor of $\pi^0\gamma^*\gamma^* is found. The slope is predicted. The contribution to muon g-2 is calculated.
We consider QCD radiative corrections to the production of colourless high-mass systems in hadron collisions. The logarithmically-enhanced contributions at small transverse momentum are treated to all perturbative orders by a universal…
In this work, we discuss both relativistic and perturbative QCD corrections to the transition form-factor ${\cal F}_{\eta_Q}{(t_1,t_2)}$ for the process $\gamma^*(q_1) \gamma^*(q_2) \leftrightarrow \eta_Q(P)$ with dependencies on the…
We report results on the $\pi$-$\gamma$ transition form factor obtained within the hard scattering approach including transverse momentum effects and Sudakov corrections. The results clearly favor distribution amplitudes close to the…
A theoretical analysis is presented for the excitation of single many-electron atoms and ions by twisted (or vortex) light. Special emphasis is put on excitations that can proceed via several electric and magnetic multipole channels. We…
We discuss the exclusive radiative B-meson decays B -> K* gamma and B -> rho gamma in a model-independent manner. The analysis is based on the heavy-quark limit of QCD. This allows a factorization of perturbatively calculable contributions…
We evaluate in the next-to-leading approximation the forward impact factor for the virtual photon to light vector meson transition in the case of longitudinal polarization. We find that in the hard kinematic domain, both in the leading and…
Non-leading contribution to the pion electromagnetic form factor which comes from the pion twist-3 wave function is analyzed in the modified hard scattering approach (MHSA) proposed by Li and Sterman. This contribution is enhanced…
The gauge invariant quark Green's function, defined with a path-ordered phase factor along a straight line, is studied in two-dimensional QCD in the large-N_c limit by means of an exact integrodifferential equation. It is found to be…
The factorisation of the hard amplitude for exclusive meson production in deep inelastic scattering is considered in the framework of a simple model. It is demonstrated explicitly how gauge invariance ensures the cancellation of…
We show that natural noncommutative gauge theory models on $\mathbb{R}^3_\lambda$ can accommodate gauge invariant harmonic terms, thanks to the existence of a relationship between the center of $\mathbb{R}^3_\lambda$ and the components of…
We discuss form factors and coupling constants for the $\gamma^* \pi^0 \gamma$, $\rho\pi\pi$ and $\gamma \pi \rho$ interactions generated by a model field theory that produces finite size $\bar{q}q$ meson modes. The approach implements…
The gauging of equations method, introduced in the preceding paper, is applied to the four-dimensional integral equations describing the strong interactions of three identical relativistic particles. In this way we obtain gauge invariant…
The main aspects of a gauge-invariant approach to the description of quark dynamics in the nonperturbative regime of QCD are first reviewed. In particular, the role of the parallel transport operation in constructing gauge-invariant Green's…
The chiral-odd transversity generalized parton distributions of the nucleon can be accessed experimentally through the exclusive photoproduction process gamma N -> pi rhoT N', with or without beam and target polarization, provided the…
The proton to $\Delta^+$ resonance transitional gravitational form factors are calculated to leading one-loop order using chiral perturbation theory in our recent work [1]. We take into account the leading electromagnetic and strong…
At high energy scale the only quantum effect of any asymptotic free and asymptotically conformal invariant GUT is the trace anomaly of the energy-momentum tensor. Anomaly generates the new degree of freedom, that is propagating conformal…