arXiv subjects

Håkan Snellman

Publications and source records attributed to Håkan Snellman.

3 recordsLinked to original sources

arXiv1995

Evidence for mass dependent effects in the spin structure of baryons

We analyze the axial-vector form factors of the nucleon hyperon system in a model with mass dependent quark spin polarizations. This mass dependence is deduced from an earlier analysis\cite{jlhs,jlhs2} of magnetic moment data, and implies that the spin contributions from the quarks to a baryon decrease with the mass of the baryon. When applied to the axial-vector form factors, these mass dependent spin polarizations bring the various sum-rules from the model in better agreement with experimental data. Our analysis leads to a reduced value for the total spin polarization of the proton.

hep-ph↗

arXiv1995

Magnetic moments of the 3/2 resonances and their quark spin structure

We discuss magnetic moments of the $J=3/2$ baryons based on an earlier model for the baryon magnetic moments, allowing for flavor symmetry breaking in the quark magnetic moments as well as a general quark spin structure. From our earlier analysis of the nucleon-hyperon magnetic moments and the measured values of the magnetic moments of $Δ^{++}$ and $Ω^{-}$ we predict the other magnetic moments and deduce the spin structure of the resonance particles. We find from experiment that the total spin polarization of the decuplet baryons, $ΔΣ(3/2)$, is considerably smaller than the non-relativistic quark model value of 3, although the data is still not good enough to give a precise determination.

hep-ph↗

arXiv1994

Flavor symmetry breaking in quark magnetic moments

We discuss the magnetic moments of the baryons allowing for flavor symmetry breaking in the quark magnetic moments. We show that there is a correlation between isospin symmetry breaking and data for the nucleon spin structure obtained from deep inelastic scattering. For small values of the isospin symmetry breaking, of the order of $5\%$, the magnetic moments and weak axial-vector form factors alone indicate a value of the spin polarization $ΔΣ\leq 0.20$. Larger values of the spin polarization are compatible only with large isospin symmetry breaking. We also calculate weak axial-vector form factors, which are independent of the symmetry breakings, from magnetic moment data and find good agreement with experiment.

hep-ph↗