Related papers: Spectator-model operators in point-form relativist…
A parameter-free evaluation of the $N - P_{11}(1440)$ electromagnetic transition form factors is performed within a light-front constituent quark model, using for the first time the eigenfunctions of a mass operator which generates a large…
We study the electromagnetic form factors, decay constants and charge radii of the pion and kaon within the framework of light-front field theory formalism where we use an ansatz for the quark-meson interaction bound-state function which is…
In this contribution I will try to give an overview of what has been achieved in constituent quark models of mesons and baryons by a comparison of some selected results from various ansaetze with experimental data. In particular I will…
The interplay between spectator and participant matter in heavy-ion collisions is investigated in the context of a microscopic transport model. Transport simulations show that flow patterns for the participant matter are strongly influenced…
We study the formation of large hyper-fragments in relativistic heavy-ion collisions within two transport models, DCM and UrQMD. Our goal is to explore a new mechanism for the formation of strange nuclear systems via capture of hyperons by…
The comparison of form factors calculated from a single-particle current in different relativistic quantum mechanic approaches evidences tremendous discrepancies. The role of constraints coming from space-time translations is considered…
Partial wave scattering amplitudes in baryon-baryon and baryon-antibaryon collisions and amplitudes for the production and decay of baryon resonances are constructed in the framework of the spin-momentum operator expansion method. The…
On the basis of the three-particle Bethe-Salpeter equation we formulated a relativistic quark model for baryons. Assuming the propagators to be given by their free form with constituent quark masses and the interaction kernel by an…
We discuss recent results of hadron spectroscopy and hadron-hadron interaction within a quark model framework. New experimental data could point to the important role played by higher order Fock space components on low-energy observables.…
We demonstrate that a relativistic constituent-quark model can give nucleon form factors in agreement with data for both low and high momentum transfer. The relativistic features of the model and the specific form of the wave function are…
The electromagnetic and axial form factors of the nucleon and its lowest positive parity excitations, the Delta(1232) and the N*(1440), are calculated with constituent-quark models that are specified by simple algebraic representations of…
This thesis has been devoted to the study of different properties of hadrons with one and two heavy quarks $c$ and/or $b$. All calculations have been done in the framework of a nonrelativistic constituent quark model. In order to check the…
The dependence of inclusive weak decay rates of heavy hadrons on light spectator quarks is considered. The analysis of a previous work on relating the effects in b baryons to those in charmed baryons is extended to explicit evaluation of…
The electromagnetic form factors of the $\rho$ meson are evaluated adopting a relativistic constituent quark model based on the light-front formalism, and using a meson wave function with the high-momentum tail generated by the…
Smooth transitions from hadronic matter to hot and dense matter of quantum chromodynamics accompany continuous transformations in effective degrees of freedom. The microscopic descriptions should include relativistic quarks interacting…
Relational Quantum Mechanics (RQM) treats quantum states as observer-dependent facts rather than absolute properties. While this relational stance is conceptually attractive, it raises concerns about empirical confirmation, particularly in…
We apply the covariant spectator quark model to the study of the electromagnetic structure of the $N^\ast(1520)$ state ($J^{P}= \frac{3}{2}^-$), an important resonance from the second resonance region in both spacelike and timelike regimes.…
Long-distance effects in exclusive rare semileptonic transitions B -> (K, K*) are analysed within a relativistic quark model. The meson transition form factors, describing the meson amplitudes of the effective weak Hamiltonian, are…
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…
A possible explanation of the apparent disrepency between the theoretical prediction and experimental measurement of the ratio of lifetimes $\tau(\Lambda_b)/\tau(B_d)$ is that ``spectator effects'', which appear at $O(1/m_b^3)$ in the heavy…