eta-^4He Bound States in the Skyrme Model
The rational map ansatz for light nuclei in the Skyrme model is shown to imply the existence of an η-^4He bound state, with a binding energy of ~ 30 KeV.
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arXiv subjects
N. N. Scoccola
Publications and source records attributed to N. N. Scoccola.
Perturbative description of nuclear double beta decay transitions
A consistent treatment of intrinsic and collective coordinates is applied to the calculation of matrix elements describing nuclear double beta decay transitions. The method, which was developed for the case of nuclear rotations, is adapted to include isospin and number of particles degrees of freedom. It is shown that the uncertainties found in most models, in dealing with these decay modes, are largely due to the mixing of physical and spurious effects in the treatment of isospin dependent interactions.
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Strange Multiskyrmions
Using the recently proposed approximation for multiskyrmion fields based on rational maps we study the masses and baryonic radii of some strange multibaryons within the bound state soliton model. We find the tetralambda binding to be stronger than previously expected. In addition, the model predicts the existence of a ``heptalambda'' which is stable against strong decays.
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$ΔS = 1$ Hadronic Weak Decays of Hyperons in a Soliton Model
We study the parity violating hyperon non-leptonic weak decays in the three flavor Skyrme model. We follow the approach in which the symmetry breaking terms in the action are diagonalized exactly within the collective coordinate approximation. We show that although this method introduces some configuration mixing, the $ΔI =1/2$ rule is numerically well satisfied. In addition, and in contrast to previous calculations, we show that not only the relative amplitudes are in good agreement with the empirical values but also their absolute values. The issue of whether the strong interaction enhancement factors should be included in soliton calculations is also addressed.
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Baby skyrmions on the sphere
We study a model for two-dimensional skyrmions on a sphere of radius L. Such model simulates a skyrmion lattice of density W/(2 πL^2), where W is the skyrmion winding number. We show that, to a very good approximation, physical results depend only on the product αL^4, where αis the strength of potential term. In the range αL^4 approx. or less than 3 the order parameter vanishes, there is a uniform distribution of the density over the whole surface and the energy of the W=2 sector lies above twice the energy of the W=1 sector. If αL^4 approx. or greater than 6 the order parameter approaches unity and the density concentrates near one of the poles. Moreover the disoliton is always bound. We also present a variational solution to the field equations for which the pure αL^4-dependence is exact. Finally, some consequences of our results for the Quantum Hall Effect are discussed.
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Rho meson properties in the Nambu-Jona-Lasinio model
Some properties of the rho vector meson are calculated within the Nambu-Jona-Lasinio model, including processes that go beyond the random phase approximation. To classify the higher order contributions, we adopt $1/N_c$ as expansion parameter. In particular, we evaluate the leading order contributions to the $ρ\rightarrow ππ$ decay width, obtaining the value $Γ= 118$ MeV, and to the shift of the rho mass which turns out to be lowered by 64 MeV with respect to its RPA value. A set of model parameters is determined accordingly.
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Strangeness Dependence in Radiative Hyperon Decay Amplitudes
The radiative decays of the $(3/2)^+$ baryons are studied in the three flavor generalization of the Skyrme model. The kaon fields are treated in the slow rotator approach which properly accounts for the observed deviations from the $U$-spin relations for the hyperon magnetic moments. This makes possible a critical discussion of the $U$-spin selection rules for the radiative hyperon decays. The variation of the decay widths with strangeness is studied and a comparison with other treatments of the $SU(3)$ Skyrme model is performed in order to analyze the effects of flavor symmetry breaking.
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SU(3) Symmetry Breaking and Octet Baryon Polarizabilities
Static polarizabilities of the low--lying $1/2^+$ baryons are studied within the collective coordinate approach to the three flavor generalization of the Skyrme model; in particular, magnetic polarizabilities are considered. Predicted polarizabilities, which result from different treatments of the strange degrees of freedom in this model, are critically compared. Their deviations from the flavor symmetric formulations are discussed.
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HYPERON RADIATIVE DECAYS IN THE BOUND STATE SOLITON MODEL
The radiative decays of hyperons are studied in the framework of the bound state soliton model. Detailed predictions for the total decay widths and the E2/M1 ratios corresponding to decuplet--to--octet electromagnetic transitions are presented in relation to future planned experiments at CEBAF and Fermilab. The results are compared to those obtained in quark based models.
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Becchi-Rouet-Stora-Tyutin quantization of a soliton model in 2+1 dimensions
The Becchi-Rouet-Stora-Tyutin (BRST) method is applied to the quantization of the solitons of the non-linear $O(3)$ model in $2+1$ dimensions. We show that this method allows for a simple and systematic treatment of zero-modes with a non-commuting algebra. We obtain the expression of the BRST hamiltonian and show that the residual interaction can be perturbatively treated in an IR-divergence-free way. As an application of the formalism we explicitly evaluate the two-loop correction to the soliton mass.
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Lambda(1405) in the Bound State Soliton Model
The strong and electromagnetic properties of the Lambda(1405) hyperon are studied in the framework of the bound state soliton model. We explicitly evaluate the strong coupling constant g(Lambda^*-N-K), the Lambda^* magnetic moment, mean square radii and radiative decay amplitudes. The results are shown to be in general agreement with available empirical data. A comparison with results of other models is also presented.
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Hyperons in the bound state approach with vector mesons
We investigate a model for hyperons based on the bound state approach in which vector mesons are explicitly incorporated. We show that for empirical values of the mesonic parameters the strange hyperon spectrum is well reproduced. We also discuss the extension of the model to heavier flavors. We show that the explicit presence of the heavy vectors leads to good predictions for the heavy baryon masses.
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Dibaryons as axially symmetric skyrmions
Dibaryons configurations are studied in the framework of the bound state soliton model. A generalized axially symmetric ansatz is used to determine the soliton background. We show that once the constraints imposed by the symmetries of the lowest energy torus configuration are satisfied all spurious states are removed from the dibaryon spectrum. In particular, we show that the lowest allowed state in the $S=-2$ channel carries the quantum numbers of the H particle. We find that, within our approximations, this particle is slightly bound in the model. We discuss, however, that vacuum effects neglected in the present calculation are very likely to unbind the H.
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Bound State Soliton Description of Low Partial Wave Octet Baryon Resonances
A version of the bound state soliton model which allows both $η$ and $K$ bound states is used to study low partial wave octet baryon resonances. It is found that negative parity $S-$wave resonances are well described within this framework. A possible interpretation of the $P-$wave resonances is also discussed.
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