Related papers: Polarization observables in vector meson photoprod…
We point out a significance of ultraperipheral photoproduction of vector mesons in the Coulomb field of nuclei as a means of measuring the radius of the neutral vector meson. This new contribution to the production amplitude is very small…
A new criterion is developed which provides a check as to whether a chosen set of polarization observables is complete with respect to the determination of all independent $T$-matrix elements of a reaction of the type $a+b\to c+d+...$. As…
Isobaric models for the photo-production of K$^+$ are discussed and their predictions are shown in the K$^0$ photo-production. The models are further used in spectator model calculations of the K$^0$ photo-production on deuteron.…
Little information is known about the polarization of gluons inside a longitudinally polarized proton. We investigate the sensitivity of photoproduction experiments with both beam and target longitudinally polarized to the polarization of…
The spin polarization of hadrons is a key observable for probing the details of particle and nuclear interactions, offering information not available from other measurements. Currently, general-purpose spectrometers lack the capability to…
We have investigated exclusive photoproduction of light vector mesons ($\omega$, $\rho$ and $\phi$) on the nucleon at low energies. In order to explore the questions concerning the so-called missing nucleon resonances, we first establish…
Model-independent identities and inequalities relating the various spin observables of a reaction are reviewed in a unified formalism, together with their implications for dynamical models, their physical interpretation, and the quantum…
We study in perturbative QCD the helicity ampltiudes of the process $\gamma^{*} p \to \rho p $ at large virtualities $Q$ of the photon $\gamma^{*}$. We estimate all spin flip amplitudes taking into account an important effect of the scale…
A formalism is developed for the partial wave analysis of data on meson photoproduction off deuterons and applied to photoproduction of $\eta$ and $\pi^0$ mesons. Different interpretations of a dip-bump structure of the $\eta$…
The study of nucleon resonances in electromagnetic meson production with the CLAS detector is discussed. The electromagnetic interaction is complementary to pion scattering in the exploration of the nucleon excitation spectrum. Higher mass…
Some open topics in the field of low energy photon-nucleon interactions are discussed--which in my opinion are of interest both for obtaining new information on nucleon structure as well as for precision tests of our theoretical…
Recoil proton polarization observables were measured for both the p($\vec {\rm e}$,e$^\prime\vec{\rm p}\,$) and d($\vec {\rm e}$,e$^\prime\vec{\rm p}\,)$n reactions at two values of Q$^2$ using a newly commissioned proton Focal Plane…
We study light hadron leptoproduction at small $x$. Vector meson production is analysed in terms of generalized gluon distributions with taking into account the transverse quark motion. Within a two-gluon model the double spin asymmetries…
General expressions for all parity-conserving polarization observables of elastic electron-nucleon scattering in the one-photon exchange approximation are derived for a general frame of reference, i.e.\ not assumming scattering off a…
We study spin asymmetries in diffractive $Q \bar Q$ and vector meson production which are sensitive to the spin-dependent part of the two-gluon-nucleon coupling. It is found that the $A_{ll}$ and $A_{lT}$ asymmetry in diffractive reactions…
Little information is known about the polarization of gluons inside a longitudinally polarized proton. I report on the sensitivity of photoproduction experiments to it. Both jet and heavy quark production are considered.
An unified approach for vector meson photoproduction is presented in the constit quark model. The s- and u-channel resonance contributions are generated using an effective quark vector-meson Lagrangian. In addition, taking into account…
By exploiting the underlying symmetries of the relative phases of the pseudoscalar meson photoproduction amplitude, we determine all the possible sets of four double-spin observables that resolve the phase ambiguity of the amplitude in…
Generalized parton distributions describe the correlations between the longitudinal momentum and the transverse position of quarks and gluons in a nucleon. They can be constrained by measuring photon leptoproduction observables, arising…
In a framework for nonperturbative QCD calculation of high energy processes, the amplitudes for photo- and electroproduction of vector mesons are written as integrals of the overlap product of photon and vector meson wave functions,…