相关论文: Using the Single Quark Transition Model to predict…

Elementary particles such as quarks and gluons are expected to be fundamental degrees of freedom at ultra high temperatures or densities, while natural phenomena in our daily lives are described in terms of hadronic degrees of freedom.…

A representation of the amplitude $\gamma^*(q^2)\to\gamma\pi\pi$ is proposed which combines large $N_c$ chiral resonance Lagrangian modelling with general unitarity and analyticity properties. The amplitude is constrained from…

We employ the Boltzmann equation for describing hadron production from a quark-gluon plasma (QGP) in ultrarelativistic heavy-ion collisions. We propose resonance formation in quark-antiquark scattering as the dominant meson-production…

We use a recent formalism of the weak hadronic reactions that maps the transition matrix elements at the quark level into hadronic matrix elements, evaluated with an elaborate angular momentum algebra that allows finally to write the weak…

The helicity dependence of the $\vec{\gamma} \vec{p} \to p \pi^0$ reaction has been measured for the first time in the photon energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4$\pi$-detector…

The momentum distributions of the constituent quarks inside the nucleon and the prominent electroproduced nucleon resonances are investigated in the two most sophisticated, available quark potential models, based respectively on the…

We present a general representation for the nucleon distribution amplitudes and for the nucleon to pion transition distribution amplitudes in terms of light-cone wave functions. We apply our formalism to a light-cone constituent quark model…

We apply the solution to the recursion relation for the double-off-shell quark current to the problem of computing one loop amplitudes with an arbitrary number of gluons. We are able to compute amplitudes for photon-gluon scattering,…

Motivated by the last experimental and theoretical advances in the analysis of possible baryonium resonances, the $X(1835)$ and their partners, we perform a constituent-quark-model based coupled-channels calculation of the proton-antiproton…

We have made the first measurements of the virtual Compton scattering process via the e p -> e p gamma exclusive reaction at Q**2 = 1 GeV**2 in the nucleon resonance region. The cross section is obtained at center of mass (CM) backward…

We identify quark and gluon helicity-flip distributions defined between nucleon states of unequal momenta. The evolution of these distributions with change of renormalization scale is calculated in the leading-logarithmic approximation. The…

In this paper, we present for the first time comprehensive and detailed results on the correspondence between the extrapolated deep inelastic structure function $g_1$ of both the proton and the neutron with the same quantity measured in the…

We calculate the one-loop QCD virtual corrections to all helicity amplitudes for parton level virtual Compton scattering processes. We include the amplitudes both on quark target process $\gamma^* q\to\gamma q$ and on gluon target process…

We construct an exact analytic solution of the revised small-$x$ helicity evolution equations, where the contributions of the quark-to-gluon and gluon-to-quark transition operators were newly included. These evolution equations are written…

We present a calculation of the deuteron wave function including $NN$, $\Delta\Delta$, and $NN^*$(1440) channels. All the transition potentials, as well as the direct $NN$ potential, have been obtained from the same underlying quark model…

We introduce the transition-density formalism, an efficient and general method for calculating the interaction of external probes with light nuclei. One- and two-body transition densities that encode the nuclear structure of the target are…

We investigate the A$(\pi^+,K^+){_\Lambda}$A reaction within a covariant model. We consider those amplitudes which are described by creation, propagation and decay into relevant channel of $N^*$(1650), $N^*$(1710), and $N^*$(1720)…

For the calculation of polarization transfer observables for quasielastic scattering of protons on nuclei, a formalism in the context of the Relativistic Plane Wave Impulse Approximation is developed, in which the interaction matrix is…

The Born approximation to the quark-gluon-exchange mechanism for K$^+$N scattering is used as a starting point to generate a potential for this system. The valence quark wave function of the nucleon is generalized from a single Gaussian to…

The constraints followed from gauge invariance and analyticity are considered for the amplitudes of radiative transitions of composite systems when composite systems are treated in terms of spectral integrals. We discuss gauge-invariant…