The Low-Energy Theorem of Pion Photoproduction in Soliton Models of the Nucleon

We derive an analytic expression for the Kroll-Ruderman amplitude up to the order 1/N_C for general Skyrme-type models of the nucleon. Due to the degeneracy of intermediate N- and Delta-states we find deviations from the standard low-energy theorem for the photoproduction of neutral pions.Comment: 17 pages, LATEX, SI-93-TP3S

Bag Formation in Quantum Hall Ferromagnets

Charged skyrmions or spin-textures in the quantum Hall ferromagnet at filling factor nu=1 are reinvestigated using the Hartree-Fock method in the lowest Landau level approximation. It is shown that the single Slater determinant with the minimum energy in the unit charge sector is always of the hedgehog form. It is observed that the magnetization vector's length deviates locally from unity, i.e. a bag is formed which accommodates the excess charge. In terms of a gradient expansion for extended spin-textures a novel O(3) type of effective action is presented, which takes bag formation into account.Comment: 13 pages, 3 figure

Beyond CP violation: hadronic physics at BaBar

I report on recent studies of hadronic physics performed by the BaBar Collaboration. Emphasis is given to the measurement of the properties of newly discovered charmed hadrons and to the searches for light and heavy pentaquarks.Comment: 14 pages, 20 postscript figues, contributed to the Proceedings of the First APS Topical Group Meeting on Hadron Physics, Fermilab, Batavia, IL (October 24-26, 2004

The Casimir energy of skyrmions in the 2+1-dimensional O(3)-model

One-loop quantum corrections to the classical vortices in 2+1 dimensional O(3)-models are evaluated. Skyrme and Zeeman potential terms are used to stabilize the size of topological solitons. Contributions from zero modes, bound-states and scattering phase-shifts are calculated for vortices with winding index n=1 and n=2. For both cases the S-matrix shows a pronounced series of resonances for magnon-vortex scattering in analogy to the well-established baryon resonances in hadron physics, while vortices with n>2 are already classically unstable against decay. The quantum corrections destabilize the classically bound n=2 configuration. Approximate independence of the results with respect to changes in the renormalization scale is demonstrated.Comment: 24 pages LaTeX, 14 figure

Strangeness, charm and bottom in a chiral quark-meson model

In this paper we investigate an SU(3) extension of the chiral quark-meson model. The spectra of baryons with strangeness, charm and bottom are considered within a "rigid oscillator" version of this model. The similarity between the quark part of the Lagrangian in the model and the Wess-Zumino term in the Skyrme model is noted. The binding energies of baryonic systems with baryon number B=2 and 3 possessing strangeness or heavy flavor are estimated. The results obtained are in good qualitative agreement with those obtained previously in the topological soliton (Skyrme) model.Comment: 12 pages, no figures. Journal ref: submitted to Nucl.Phys.

Strange and Heavy Flavoured Hypernuclei in Chiral Soliton Models

The extention of the chiral soliton approach to hypernuclei - strange or heavy flavoured - becomes more reliable due to success in describing of other properties of nuclei, e.g. the symmetry energy of nuclei with atomic numbers up to ~30. The binding energies of the ground states of light hypernuclei with strangeness S=-1 have been described in qualitative agreement with data. The existence of charmed or beautiful hypernuclei and Theta-hypernuclei (strange, charmed or beautiful) with large binding energy is expected within same approach.Comment: 5 pages, 4 figures. Talk given at the 9-th International Conference on Hypernuclei and Strange Particle Physics (HYP2006), Mainz, Germany, 10-14 October 2006. Extended version "Baryon States in Chiral Soliton Models; from Nuclei to Exotic Baryons" presented at the International Workshop "High Energy Physics in the LHC Era", Universidad Tecnica Federico Santa Maria, Valparaiso, Chile, 11-15 December 200

Flavored exotic multibaryons and hypernuclei in topological soliton models

The energies of baryon states with positive strangeness, or anti-charm (-beauty) are estimated in chiral soliton approach, in the "rigid oscillator" version of the bound state soliton model proposed by Klebanov and Westerberg. Positive strangeness states can appear as relatively narrow nuclear levels (Theta-hypernuclei), the states with heavy anti-flavors can be bound with respect to strong interactions in the original Skyrme variant of the model (SK4 variant). The binding energies of anti-flavored states are estimated also in the variant of the model with 6-th order term in chiral derivatives in the lagrangian as solitons stabilizer (SK6 variant). The latter variant is less attractive, and nuclear states with anti-charm or anti-beauty can be unstable relative to strong interactions. The chances to get bound hypernuclei with heavy antiflavors are greater within "nuclear variant" of the model with rescaled model parameter (Skyrme constant e or e' decreased by ~30%) which is expected to be valid for baryon numbers greater than B ~10. The rational map approximation is used to describe multiskyrmions with baryon number up to ~30 and to calculate the quantities necessary for their quantization (moments of inertia, sigma-term, etc.).Comment: 24 pages, 7 table

Dynamics of topological solitons in two-dimensional ferromagnets

Dynamical topological solitons are studied in classical two-dimensional Heisenberg easy-axis ferromagnets. The properties of such solitons are treated both analytically in the continuum limit and numerically by spin dynamics simulations of the discrete system. Excitation of internal mode causes orbital motion. This is confirmed by simulations.Comment: LaTeX, 15 pages, 6 figure

Resonances, and mechanisms of Theta-production

After explaining necessity of exotic hadrons, we discuss mechanisms which could determine production of the exotic Theta-baryon. A possible important role of resonances (producing the Theta in real or virtual decays) is emphasized for various processes. Several experimental directions for studies of such resonances, and the Theta itself, are suggested. We briefly discuss also recent negative results on the Theta-baryon.Comment: 6 page