相关论文: Structure of the nucleon's low-lying excitations
A continuum approach to the three valence-quark bound-state problem in quantum field theory, employing parametrisations of the necessary kernel elements, is used to compute the spectrum and Poincar\'e-covariant wave functions for all…
A Poincar\'e-covariant continuum approach to the three valence-quark bound-state problem in quantum field theory is used to perform a detailed analysis of the nucleon's ground and first excited states: the so-called $N(940)\frac{1}{2}^+$…
Using a Poincar\'e-covariant quark+diquark Faddeev equation, we provide structural information on the four lightest $(I,J^P)=(\tfrac{1}{2},\tfrac{3}{2}^\mp)$ baryon multiplets. These systems may contain five distinct types of diquarks; but…
We use a symmetry-preserving truncation of meson and baryon bound-state equations in quantum field theory in order to develop a unified description of systems constituted from light- and heavy-quarks. In particular, we compute the spectrum…
A Poincar\'e-covariant quark+diquark Faddeev equation is used to develop insights into the structure of the four lightest $(I,J^P=\tfrac{3}{2},\tfrac{3}{2}^\pm)$ baryon multiplets. Whilst these systems can contain isovector-axialvector and…
In this thesis a model framework for describing baryons as diquark-quark bound states is presented which is formulated in an explicitly covariant manner. The relativistic bound state problem for three quarks is considered. Diquarks are…
Supposing quark--diquark structure of baryons, we look for systematics of baryons composed of light quarks ($q=u,d$). We systematize baryons using the notion of two diquarks: (i) axial--vector state, $D^{1}_{1}$, with the spin $S_D=1$ and…
I give an overview on experimental studies of the spectrum and the structure of the excited states of the nucleon and what we can learn about their internal structure. One focus is on the efforts to obtain a more complete picture of the…
The nucleon-nucleon interaction at short range is analyzed in terms of six-quark configurations on a base of numerical solutions of modified RGM equations. It is shown that in low partial waves L=0,1 the system has a two-channel character:…
The electroweak properties of nucleons and hyperons are calculated in a relativistic constituent quark model. The baryons are treated as three quark bound states, and the diagrams of perturbation theory are considered on the light front.…
In this two part series a chiral confining model of baryons is used to describe low--lying negative parity resonances $N^*$, $\Delta^*$, $\Lambda^*$ and $\Sigma^*$ in the mean field approximation. A physical baryon in this model consists of…
Analyses of the three valence-quark bound-state problem in relativistic quantum field theory predict that the nucleon may be understood primarily as a Borromean bound-state, in which binding arises mainly from two separate effects. One…
We summarise recent results on the spectrum of ground-state and excited baryons and their form factors in the framework of functional methods. As an improvement upon similar approaches we explicitly take into account the underlying…
The coupling to light mesons leads to large widths and shifts of the energy of the excited states in the baryon spectrum from the predictions of the constituent quark model with three valence quarks. This coupling may be modelled by…
We continue our attempts to systematize baryons, which are composed of light quarks ($q=u,d$), as quark--diquark systems. The notion of two diquarks is used: (i) $D^{1}_{1}$, with the spin $S_D=1$ and isospin $I_D=1$ and (ii) $D^{0}_{0}$,…
We explain how the emergent phenomenon of dynamical chiral symmetry breaking ensures that Poincar\'e covariant analyses of the three valence-quark scattering problem in continuum quantum field theory yield a picture of the nucleon as a…
Using a confining, symmetry-preserving regularisation of a vector$\times$vector contact interaction, we compute the spectra of ground-state pseudoscalar and vector $(f\bar g)$ mesons, scalar and axial-vector $(fg)$ diquarks, and $J^P=1/2^+,…
This is the second of a series of three papers treating light baryon resonances up to 3 GeV within a relativistically covariant quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In…
QCD instantons are known to produce deeply bound diquarks. We study whether it may be used as building blocks in the formation of multiquark states, in particular pentaquarks and dibaryons. A simple model is presented in which the lowest…
I give a brief overview of experimental studies of the spectrum and the structure of the excited states of the nucleon and what we learn about their internal structure. The focus is on the effort to obtain a more complete picture of the…