Density dependence of meson-nucleon vertices in nuclear matter

Abstract

and TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3 Changes in the meson-nucleon coupling constant and the vertex form factor in nuclear matter are studied in a modified Skyrme Lagrangian including the σ-meson field that satisfies the scale invariance. Renormalization of g A , the axial-vector coupling constant, and the nucleon mass are studied in a consistent model. The results are in good agreement with the empirical evidence. A calculation of the π-N commutator, Σ-term, indicates that the medium changes its magnitude considerably. PACS number(s): 12.39.Dc, 12.39.Fe Key words: Skyrme model, in-medium hadron properties, meson-nucleon coupling constants, vertex form factors, medium renormalization.Recently arguments have been given in favor of the empirical evidence for a scalarisoscalar meson, σ. For example the isosinglet resonance with a mass m σ = 553.3 ± 0.5 MeV 2 The similar second order derivative terms had been suggested in ref [7].

Nucleon deformation in finite nuclei

“…the shell structure of the nuclei, then all nucleons will be situated at some distances (within the shells) from their mass center and the mean effective value of the nucleon mass in such systems will be further reduced for nucleons in heavy nuclei. Further improvements of the results can be made by including a dilaton field [20,2,21]. We also note that a similar renormalization of the nucleon mass was found in Ref.…”

“…One way to consider such problems is to describe the nucleon as a topological soliton and then study the influence of baryonic matter on the properties of such solitons, making use of the independent particle picture which has been so successful in describing many properties of nuclei. There exist already some works where nucleons described as Skyrme-type solitons embedded in infinite nuclear matter have been considered [1,2].…”

QCD condensates and hadron parameters in nuclear matter: self-consistent treatment, sum rules and all that

“…The model did not reproduce the attraction in NN potential. It was included into modified Skyrme Lagrangian by Rakhimov et al [93] in order to calculate the renormalization of g A , m and f π in nuclear matter. The magnitude of renormalization appeared to be somewhat smaller than in QHD.…”

“…This is why the "pole+continuum" model was employed for the description of Im G(k 2 ) in the rhs of Eq. (93). This means that the contribution of the lowest lying hadron was treated explicitly, while all the other excitations were approximated by continuum.…”

“…The empirical data are used for the spectral function Im G(k 2 ) in the rhs of Eq. (93). Namely, we know, that the lowest lying state is the bound state of three quarks, which manifests itself as a pole in the (unknown) point k 2 = m 2 .…”