186226232
Chiral hyperbags
We construct and studySU (3) chiral bags (called chiral hyperbags) in the scheme of collective-coordinate quantization with chiral symmetry breaking treated as perturbation. We show how the Wess-Zumino constraint arises from the quark-bag sector, complementing the soliton sector, in a manner analogous to what happens in (1+1) dimensional chiral bags. Due to the Wess-Zumino term, all the quantum numbers — baryon charge, isopin, angular momentum, hypercharge etc. are fractionized in a prescribed manner. One notable aspect of the fractionization is that for all ranges of bag radius, there is alwaysmore angular momentum lodged in the soliton sector than in the quark sector. It is shown thatwithin the scheme we have adopted, the symmetry breaking termobstructs the Cheshire Cat principle and that consequently when strange quarks are present, the baryons (i.e. hyperons) favor a bigger bag (say R ⪆ 1 fm) than non-strange baryons; this confirms a phenomenological argument put forward some time ago by Brown, Klimpt, Rho and Weise (at least in the collective-coordinate scheme). Our approach allows us to calculate the strangeness content of the proton — a highly topical issue — and we find that while a perturbative treatment of the symmetry breaking term can be made to work (for a big bag) for hyperon spectroscopy, the strangeness content of the proton is insensitive to the bag radius; for relevant ranges of bag radius, the ¯ss admixture stays significant, say, ⪆19%. This result is in stark contrast to the Callan-Klebanov Skyrmion — a remarkably successful model for hyperons — which predicts only about 3%. A subtle role of the Wess-Zumino term is suggested.
119359306
Neutral pion decay in dense Skyrmion matter
We study the density dependence of the decay {pi}{sup 0}{yields}{gamma}{gamma} using the Skyrme Lagrangian to describe simultaneously both the matter background and mesonic fluctuations. The classical ground state configuration has different chiral properties depending on the Skyrmion density, which is reflected in the physical properties of pion fluctuating on top of the classical background. This leads to large suppression at high density of both photo-production from the neutral pion and the reverse process. The effective charges of {pi}{sup {+-}} are also discussed in the same framework.
120786968
Casimir energy of the Skyrmion due to kaon vacuum fluctuations
14302817
Vector mesons and dense skyrmion matter
Abstract In our continuing effort to understand hadronic matter at high density, we have developed a unified field theoretic formalism for dense skyrmion matter using a single Lagrangian to describe simultaneously both matter and meson fluctuations and studied in-medium properties of hadrons. Dropping the quartic Skyrme term, we incorporate into our previous Lagrangian the vector mesons ρ and ω in a form which is consistent with the symmetries of QCD. The results that we have obtained, reported here, expose a hitherto unsuspected puzzle associated with the role the ω meson plays at short distance. Since the ω meson couples to baryon density, it leads to a pseudo-gap scenario for the chiral symmetry phase transition, which is at variance with standard scenario of QCD at the phase transition. We find that in the presence of the ω mesons, the scale-anomaly dilaton field is prevented from developing a vanishing vacuum expectation value at the chiral restoration, as a consequence of which the in-medium pion decay constant does not vanish. This seems to indicate that the ω degree of freedom obstructs the “vector manifestation” which is considered to be a generic feature of effective field theories matched to QCD.
15479695
Excited states of heavy baryons in the Skyrme model.
We obtain the spectra of excited heavy baryons containing one heavy quark by quantizing the exactly solved heavy meson bound states to the Skyrme soliton. The results are comparable to the recent experimental observations and quark model predictions, and are consistent with heavy quark spin symmetry. However, the somewhat large dependence of the results on the heavy quark mass strongly calls for the incorporation of the soliton-recoil effects. {copyright} {ital 1996 The American Physical Society.}
120803195
Skyrmion and Dense Matter
Skyrme model can provide valuable insights (though qualitative) on high density physics of mesons and baryons in a unified way. First, the dense hadronic matter can be described by the soliton configuration of given meson Lagrangian, which undergoes an interesting chiral phase transition as the baryon density increases. Then, by incorporating the meson fluctuations on top of such ground state we can investigate the in-medium properties of mesons.
181523075
Measurements of pion nucleon charge exchange near the Delta resonance using the NMS at LAMPF