Spin Structure Functions in Chiral Quark Soliton Models

In this talk I review studies of hadron structure functions in bosonized chiral quark models. Such models require regularization and I show that the two--fold Pauli--Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. This scheme is consistent with other computations of the pion structure function in that model. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions and the role of strange quarks is addressed.Comment: Based on plenary talk presented at the QCD-Workshop in Charlottesville, April 2002. 12 pages Latex, uses ws-procs9x6.cls (included

Quantum Energies of Solitons

For renormalizable models a method is presented to unambiguously compute the energy that is carried by localized field configurations (solitons). A variational approach for the total energy is utilized to search for soliton configurations. As an example a 1+1 dimensional model is considered. The quantum energy of configurations that are translationally invariant for a subset of coordinates is discussed.Comment: 6 pages LaTeX with ws-p8-50x6-00.cls (included). To appear in the proceedings of the 6th workshop on non-perturbative QCD, Paris, June 200

Flavor Symmetry Breaking and Strangeness in the Nucleon

We suggest that breaking of SU(3) flavor symmetry mainly resides in the baryon wave--functions while the charge operators have no (or only small) explicit symmetry breaking components. We utilize the collective coordinate approach to chiral soliton models to support this picture. In particular we compute the $g_A/g_V$ ratios for hyperon beta--decay and the strangeness contribution to the nucleon axial current matrix elements and analyze their variation with increasing flavor symmetry breaking.Comment: 3 pages, EJPA-style. Based on talks presented at QNP 2002, Juelich, June 2002 and ''workshop on the structure of the nucleon'', Trento, Sept. 2002. To appear in the proceedings of QNP200

Pentaquarks in a Breathing Mode Approach to Chiral Solitons

In this talk I report on a computation of the spectra of exotic pentaquarks and radial excitations of the low--lying ${1/2}^+$ and ${3/2}^+$ baryons in a chiral soliton model. In addition I present model results for the transition magnetic moments between the N(1710) and the nucleon.Comment: Talk presented at the Pentaquark workshop at Spring--8, July 2004. Eight page

Casimir Energies in the Light of Renormalizable Quantum Field Theories

Effective hadron models commonly require the computation of functional determinants. In the static case these are one--loop vacuum polarization energies, known as Casimir energies. In this talk I will present general methods to efficiently compute renormalized one--loop vacuum polarization energies and energy densities and apply these methods to construct soliton solutions within a variational approach. This calculational method is particularly useful to study singular limits that emerge in the discussion of the {\it classical} Casimir problem which is usually posed as the response of a fluctuating quantum field to externally imposed boundary conditions.Comment: 14 pages, LaTeX. Talk presented at the at the second intl. workshop ``Effective Theories of Low Energy QCD'', Coimbra, Sept. 200

Vacuum Polarization Energy for General Backgrounds in One Space Dimension

For field theories in one time and one space dimensions we propose an efficient method to compute the vacuum polarization energy of static field configurations that do not allow a decomposition into symmetric and anti--symmetric channels. The method also applies to scenarios in which the masses of the quantum fluctuations at positive and negative spatial infinity are different. As an example we compute the vacuum polarization energy of the kink soliton in the $\phi^6$ model. We link the dependence of this energy on the position of the soliton to the different masses.Comment: Eight pages, corrections from proof-reading implemente

Collective Resonances in the Soliton Model Approach to Meson--Baryon Scattering

The proper description of hadronic decays of baryon resonances has been a long standing problem in soliton models for baryons. In this talk I present a solution to this problem in the three flavor Skyrme model that is consistent with large-Nc consistency conditions. As an application I discuss hadronic pentaquark decays and show that predictions based on axial current matrix elements are erroneous.Comment: Contribution to QNP06 (Madrid, June 2006), 3 pages epja styl