Related papers: Recent developments in the constituent quark model…
We propose a formulation of the QCD partition function which leads to a series expansion of the quark determinant in any given baryonic sector. The r-th term gives the gauge-invariant contribution of the valence quarks plus r…
We show that three-quark axial currents as required by broken SU(6) spin-flavor symmetry reduce the quark spin contribution to proton spin from $\Sigma_p = 1$ (one-quark axial current value) to $\Sigma_p = 0.41(12)$ consistent with the…
We study the correlation between the fermion composite system and quark spins by using the light-cone quark-diquark model. We do the calculations for $u$-quark and $d$-quark in the fermion system by considering the different polarization…
We report on recent results of the QCDSF/UKQCD Collaboration on investigations of baryon structure using configurations generated with N_f=2+1 dynamical flavours of O(a) improved Wilson fermions. With the strange quark mass as an additional…
We present results from the QCDSF/UKQCD collaboration for hyperon electromagnetic form factors and axial charges obtained from simulations using Nf=2+1 flavours of O(a)-improved Wilson fermions. We also consider matrix elements relevant for…
We have performed a study of the isovector, octet and singlet axial charges of the proton in an extended chiral constituent quark model, where all the possible $uudq\bar{q}$~($q=u,d,s$) five-quark Fock components in the proton wave function…
The structure of spin and isospin is analyzed. Although both spin and isospin are related to the same SU(2) group, they represent different dynamical effects. The Wigner-Racah algebra is used for providing a description of bound states of…
This is a summary of perturbative QCD calculations of baryon form factors. For e^+ e^- going to baryon-antibaryon pairs, normalized calculations are available and reported for the entire ground state octet and decuplet, including…
In this contribution, we briefly discuss the results for charmonium and bottomonium spectra with self-energy corrections in the unquenched quark model, due to the coupling to the meson-meson continuum. The UQM formalism can be extended to…
The CLAS Collaboration recently reported measured ratios of pion and kaon electroproduction cross sections from a proton target and extracted the ratios for light and strange quark--antiquark pairs, ${u\bar{u}}/ {d\bar{d}}$ and ${s\bar{s}}/…
A brief review on some recent progresses in our understanding of multi-quark components in baryons is presented. The multi-quark components in baryons seem to be mainly in colored quark cluster configurations rather than in ``meson cloud''…
Field distributions generated by static quark-antiquark and QQQ sources are calculated analytically in the framework of Gaussian (bilocal) approximation of Field Correlator Method (FCM). Special attention is paid to the QQQ system and…
It is pointed out that the recent data on strange baryon and antibaryon production in Pb-Pb collisions at 159 GeV/c agree well with the hypothesis of an intermediate state of quasi-free and randomly distributed constituent quarks and…
The effective interaction between a quark and an anti-quark as obtained previously with by the method of iterated resolvents is replaced by the so called up-down-model and applied to flavor off-diagonal mesons including the pion. The only…
An unified scheme for describing both spin and orbital motion in symmetry-breaking chiral quark model is suggested. The analytic results of the spin and orbital angular momenta carried by different quark flavors in the nucleon are given.…
A critical discussion is given of the results for baryon electromagnetic and axial form factors obtained from relativistic constituent quark models in the framework of Poincar\'e-invariant quantum mechanics. The primary emphasis lies on the…
The formalism of Baier-Dokshitzer-Mueller-Peign\'e-Schiff and Zakharov determines the modifications of parton splittings in the QCD plasma that arise from medium-induced gluon radiation. Here, we study medium-modifications of the gluon…
We critically discuss fragmentation of quark or antiquark to massive particles (mesons or baryons) in proton-proton collisions. Both heavy and light quark/antiquark fragmentations are discussed using universal $z$-dependent fragmentation…
A constituent quark model based on the spectator formalism is applied to the gamma N -> N* transition for the three cases, where N* is the nucleon, the Delta and the Roper resonance. The model is covariant, and therefore can be used for the…
The chiral quark model with a broken U(3) symmetry gives a simple and unified account for the proton spin and flavor puzzles, as well as the octet baryon magnetic moments.