Skyrme Term Research Articles

Soliton states in the electroweak theory

We find nontopological soliton solutions for the Weinberg-Salam model with a gauged Skyrme term for all values of the Higgs self coupling λ. These solutions approach properly the solution previously found for λ=∞. Their energy is lower and may lead, if they correspond to sufficiently stable states, to spectacular signals in future colliders.

Baryon density in a chiral soliton model

Continuity of the baryon density is introduced into a hybrid chiral soliton model. For a given value of the bag radius, unique predictions of the nucleon-$\ensuremath{\Delta}$ average mass, the axial-vector coupling constant ${g}_{A}$, the isoscalar radius, and the coupling constant of the Skyrme term are obtained.

Deformation Effect on the Skyrmion-(Anti-)Skyrmion Interaction Potential in the -Stabilized Skyrme Model

The Skyrme modeF) attracts interests both from the viewpoint of the effective lagrangian of the QeD and from the phenomenological aspect. A lot of efforts have been devoted to investigating the properties of oneand two-baryon systems by the original and generalized Skyrme models.)-9) In the course of the studies, it has been clarified) that the co-meson coupling term plays an important role in the model, and that the stabilization of the Skyrmion may depend strongly on the term. The static properties of the nucleon are known to be cosiderably improved by the model with the co-meson term, and the characteristic features of the nucleon-nucleon (NN) potential can also be fairly well reproduced by the model. One notes that the correct G-parity structure of the central potential is obtained by including the co-meson term. No improvement is, however, obtained for the medium-range attraction of the central potential; the resulting potential does not show any attraction necessary for the nuclear binding. Recently, it was shown that in the original Skyrme model the central potential is reduced by the amount of about 10 to 20% by taking into account a deformation effect of the Skyrmion.) The small amount of the reduction comes from the fact that the Skyrme term resists strongly such a deformation. On the other hand, Hajduk and Schwesinger ) showed that the co-meson term IS not influenced by the deformation of the Skyrmion. Then, it is very interesting to study to what extent the central potential in the Skyrmion-Skyrmion (SS) interaction is affected by the deformation of the Skyrmion in such a model, since the Skyrmion seems to be soft for the deformation. In this paper, we investigate such an effect on the central potential for the model of Adkins and N appi,4) where the Skyrmion is stabili~ed by the co-meson term instead of the so-called Skyrme term. There is so far no explicit calculation of the deformation effect on the Skyrmion-Skyrmion potential projected onto the central potential. The lagrangian adopted here is

Stochastic quantization of a Fermi field: Fermions as solitons

It is shown that the stochastic quantization of a fermion introducing an anisotropy in the internal space so that this gives rise to two internal helicities corresponding to particle and antiparticle leads us to describe a fermion as a Skyrme soliton. The Skyrme term appears here as a consequence of this internal anisotropy and can be treated as a quantum effect. Some topological properties of this fermionization are then discussed.

KSFR relation and the strength of the non-skyrme term

It is shown that the consistency of the KSFR relation depends on the existence of the non-Skyrme term. Its strength is determined by that of the Skyrme term. The D wave pion pion scattering lengths are found to be a 0 2 =3.5±0.4 GeV −4, a 2 2 =0.64±0.33 GeV −4 .

Effective chiral hadron lagrangian with anomalies and skyrme terms from quark flavour dynamics

By bosonization of an extended Nambu-Jona-Lasinio type of quark model with explicit breaking of chiral U( n) × U( n) symmetry we derive a effective low-energy lagrangian of composite scalar, pseudoscalar, vector and axial-vector mesons. This lagrangian contains the gauged Wess-Zumino term as well as higher order derivative terms of the Skyrme type, the coefficients of which agree with recent phenomenological estimates. In particular, the value predicted for the strength of the standard fourth-order Skyrme term is in satisfactory agreement with the results obtained by fitting the nucleon and delta masses. Our effective chiral lagrangian reproduces the wealth of the results of successful phenomenological lagrangians as, e.g. soft-pion theorems, Goldberger-Treiman relations, PCAC, the KSFR relation, the (approximate) Weinberg relation, etc. Moreover, the predicted mass spectra and decay constants of composite mesons are in qualitative agreement with the experimental findings. Furthermore, when electroweak interactions are included the lagrangian contains vector (axial-vector) dominance based on field-current identities.

Extended skyrmion model from quark flavour dynamics

From the effective chiral meson lagrangian derived recently from Nambu-Jona-Lasinio type of quark flavour dynamics, an extended skyrmion model is extracted. This model contains besides the usual Skyrme term further fourth-order derivative terms of the chiral field and in addition the ω meson field. It is shown that the net effect of all fourth-order derivative terms is to destabilize the soliton and to provide the desired medium-range attraction of the nucleon-nucleon interaction, which is responsible for nuclear binding but missing in the original Skyrme model. The soliton is stabilized by the coupling to the ω meson which produces a short-range repulsion. The corresponding equation of state of skyrmion matter is constructed and found to be in qualitative agreement with the equation of state of nuclear matter obtained from effective density-dependent forces.

Skyrmion solutions to the Weinberg-Salam model.

We find a spherically symmetric solution to the gauged ${\mathrm{SU}(2)}_{L}\ensuremath{\bigotimes}{\mathrm{SU}(2)}_{R}$ chiral model. It corresponds to a new classical solution to the Weinberg-Salam model in the limit of infinite self-coupling and ${sin}^{2}{\ensuremath{\theta}}_{\mathrm{W}}=0$. It has an energy of 11.6 TeV and is classically unstable under small perturbations of the fields. Quantum corrections may stabilize the solution via the introduction of higher-order terms in the effective action. We then investigate the solutions when a particular choice of a correction, the Skyrme term, is added to the Lagrangean. The energies of the (presumably) classically stable solutions are in the teraelectronvolt region.

Stability of the rotating Skyrmion.

We find, numerically, that internally rotating classical Skyrmions corresponding to the N and the \ensuremath{\Delta} cannot be stabilized, even in the presence of a pion-mass term, unless the fourth-order Skyrme term is also retained. We give arguments explaining this finding. Upon including the Skyrme term, and using reasonable parameters, we find that a stable localized solution exists for the N, but not for the \ensuremath{\Delta}. This is in agreement with earlier results in the literature.

Effective Chiral Hadron Lagrangian with anomalies and skyrme terms from quark flavour dynamics

By bosonization of an extended Nambu-Jona-Lasinio type of quark model with explicit breaking of chiral U( n ) × U( n ) symmetry we derive a effective low-energy lagrangian of composite scalar, pseudoscalar, vector and axial-vector mesons. This lagrangian contains the gauged Wess-Zumino term as well as higher order derivative terms of the Skyrme type, the coefficients of which agree with recent phenomenological estimates. In particular, the value predicted for the strength of the standard fourth-order Skyrme term is in satisfactory agreement with the results obtained by fitting the nucleon and delta masses. Our effective chiral lagrangian reproduces the wealth of the results of successful phenomenological lagrangians as, e.g. soft-pion theorems, Goldberger-Treiman relations, PCAC, the KSFR relation, the (approximate) Weinberg relation, etc. Moreover, the predicted mass spectra and decay constants of composite mesons are in qualitative agreement with the experimental findings. Furthermore, when electroweak interactions are included the lagrangian contains vector (axial-vector) dominance based on field-current identities.

Quasisolitons in the vector-meson sector of the Weinberg chiral model.

By adding Skyrme terms to the Weinberg Lagrangian we propose a chiral model coupled with rho mesons which admits an absolutely conserved topological charge (baryon number). This model possesses another topological charge which is not conserved because of instanton effects. We evaluate the mass and the lifetime of the quasistable soliton carrying the latter charge. It is suggested that a possible candidate for this quasistable soliton is the iota(1.4) meson.

Stabilization of skyrmions via ϱ-mesons

It is shown that a skyrion can be stabilized by introducing ϱ-mesons into the chiral SU(2) L × SU(2) R lagrangian without higher-derivative terms like the Skyrme term. The ϱ-mesons are considered as dynamical gauge bosons associated with a hidden local symmetry of the non-linear sigma model. The lagrangian reduces to the Skyrme model in a limit of parameters. The Skyrmion mass M is found to be M = 1058 MeV when the parameters are fixed so as to satisfy the KSRF relation. It is also shown that a solition solution in a model with Ω-meson coupled with the baryonic current is a saddle-point solution.

Evaluation of the derivative quartic terms of the meson chiral Lagrangian from forward dispersion relations.

Using the forward dispersion relations for \ensuremath{\pi}\ensuremath{\pi} scattering, we show that the coefficients of the derivative quartic terms in the chiral Lagrangian are positive. The Skyrme term is mainly given by the \ensuremath{\rho}-meson contribution to the I=1 total cross section and gives a proton mass of 1.27 GeV. The non-Skyrme term is found of comparable strength from the I=0 S-wave \ensuremath{\pi}\ensuremath{\pi} data.

Derivative expansions of fermion determinants: Anomaly-induced vertices, Goldstone-Wilczek currents, and Skyrme terms.

An algebraic procedure for evaluating functional determinants in powers of derivatives of external fields is used to calculate one-fermion-loop contributions to low-energy effective Lagrangians involving anomaly-induced vertices, Goldstone-Wilczek currents, and Skyrme terms.

Current Algebra, Vector Meson and the Skyrme Term

Current Algebra, Vector Meson and the Skyrme Term