B. El-Bennich

Collective perspective on advances in Dyson-Schwinger Equation QCD

We survey contemporary studies of hadrons and strongly interacting quarks using QCDs Dyson—Schwinger equations, addressing the following aspects: confinement and dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and transition form factors, from small- to large-Q2; parton distribution functions; the physics of hadrons containing one or more heavy quarks; and properties of the quark gluon plasma.

Completing the Picture of the Roper Resonance.

We employ a continuum approach to the three valence-quark bound-state problem in relativistic quantum field theory to predict a range of properties of the protons radial excitation and thereby unify them with those of numerous other hadrons. Our analysis indicates that the nucleons first radial excitation is the Roper resonance. It consists of a core of three dressed quarks, which expresses its valence-quark content and whose charge radius is 80% larger than the proton analogue. That core is complemented by a meson cloud, which reduces the observed Roper mass by roughly 20%. The meson cloud materially affects long-wavelength characteristics of the Roper electroproduction amplitudes but the quark core is revealed to probes with Q(2)≳3m(N)(2).

On the quark-gluon vertex and quark-ghost kernel: combining lattice simulations with Dyson-Schwinger equations

A bstractWe investigate the dressed quark-gluon vertex combining two established non-perturbative approaches to QCD: the Dyson-Schwinger equation (DSE) for the quark propagator and lattice-regularized simulations for the quark, gluon and ghost propagators. The vertex is modeled using a generalized Ball-Chiu ansatz parameterized by a single form actor

Exciting flavored bound states

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On the structure of the X(1835) baryonium

which effectively represents the quark-ghost scattering kernel. The solution space of the DSE inversion for

Pion and kaon elastic form factors in a refined light-front model

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Flavor SU(4) breaking between effective couplings

is highly degenerate, which can be dealt with by a numerical regularization scheme. We consider two possibilities: (i) linear regularization and (ii) the Maximum Entropy Method. These two numerical approaches yield compatible

Pion structure in the nuclear medium

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Modeling electromagnetic form factors of light and heavy pseudoscalar mesons

functions for the range of momenta where lattice data is available and feature a strong enhancement of the generalized Ball-Chiu vertex for momenta below 1 GeV. Our ansatz for the quark-gluon vertex is then used to solve the quark Dyson-Schwinger equation which yields a mass function in good agreement with lattice simulations and thus provides adequate dynamical chiral symmetry breaking.

Pseudoscalar mesons with symmetric bound state vertex functions on the light front

We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited