Kernmaterie — ein ungewöhnlicher Stoff

Eder, Günther

doi:10.1002/phbl.19680240602

Cited by 3 publications

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“…The terms from iterated 1π-exchange written down in eqs. (7)(8)(9)(10)(11)(12)(13)(14) are the unique leading order contributions in the small momentum expansion. They are of second order in small momenta as signaled by the common prefactor g 4 A Mm 2 π /(2πf π ) 4 .…”

Section: Resultsmentioning

confidence: 99%

“…In this sense, the relativistic mean-field model gives a simple and natural explanation of the basic features of the nuclear shell model potential. Refinements of relativistic mean-field models 2 General considerations about the nuclear spin-orbit term Let us begin with recalling the spin-orbit Hamiltonian of the nuclear shell model [9,10] which is generally written in the form:…”

Section: Introductionmentioning

confidence: 99%

“…δ = (N − Z)/(N + Z) is the isospin asymmetry parameter and τ 3 → ±1 for a proton or a neutron. The empirical value of the isoscalar nuclear spin-orbit strength is U ls ≃ 35 MeVfm 2 [9,10]. The ratio of the isovector and isoscalar nuclear spin-orbit strengths V ls / U ls ≃ −0.6 is commonly assumed to be equal to the ratio of the spinindependent isovector and isoscalar average nuclear potentials [9,10].…”

Section: Introductionmentioning

confidence: 99%

“…The empirical value of the isoscalar nuclear spin-orbit strength is U ls ≃ 35 MeVfm 2 [9,10]. The ratio of the isovector and isoscalar nuclear spin-orbit strengths V ls / U ls ≃ −0.6 is commonly assumed to be equal to the ratio of the spinindependent isovector and isoscalar average nuclear potentials [9,10]. We wish to calculate the nuclear spin-orbit strengths U ls and V ls (or appropriate generalization of them) in the systematic framework of in-medium chiral perturbation theory [8].…”

Section: Introductionmentioning

confidence: 99%

“…Note the similarity of the expressions eqs. (8,9,10) with the three-body isovector single-particle potentials written in eqs. (30,31,32) of ref.…”

Section: Introductionmentioning

confidence: 99%

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Isovector nuclear spin–orbit interaction from chiral pion–nucleon dynamics

Kaiser

2003

Nuclear Physics A

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Using the two-loop approximation of chiral perturbation theory, we calculate the momentum and density dependent isovector nuclear spin-orbit strength V ls (p, k f ). This quantity is derived from the spin-dependent part of the interaction energy Σ spin = i 2 σ · ( q × p )[U ls (p, k f ) − V ls (p, k f )τ 3 δ] of a nucleon scattering off weakly inhomogeneous isospinasymmetric nuclear matter. We find that iterated 1π-exchange generates at saturation density, k f 0 = 272.7 MeV, an isovector nuclear spin-orbit strength at p = 0 of V ls (0, k f 0 ) ≃ 50 MeVfm 2 . This value is about 1.4 times the analogous isoscalar nuclear spin-orbit strength U ls (0, k f 0 ) ≃ 35 MeVfm 2 generated by the same two-pion exchange diagrams. We also calculate several relativistic 1/M -corrections to the isoscalar nuclear spin-orbit strength. In particular, we evaluate the contributions from irreducible two-pion exchange to U ls (p, k f ). The effects of the three-body diagrams constructed from the Weinberg-Tomozawa ππN N -contact vertex on the isoscalar nuclear spin-orbit strength are computed. We find that such relativistic 1/M -corrections are less than 20% of the isoscalar nuclear spin-orbit strength generated by iterated one-pion-exchange, in accordance with the expectation from chiral power counting. : 12.38.Bx, 21.65.+f, 24.10.Cn Keywords: Effective field theory at finite density, Isoscalar and isovector nuclear spin-orbit interaction. PACSwhich include additional non-linear couplings of the scalar and vector fields or explicitly densitydependent point couplings of nucleons are nowadays widely and successfully used for nuclear structure calculations [3,4,5].The nuclear spin-orbit potential arises generally as a many-body effect from the underlying spin-orbit term in the (free) nucleon-nucleon scattering amplitude. The calculation of the tree level diagrams with one scalar-meson or one vector-meson exchange between nucleons gives indeed a spin-orbit term in the NN T-matrix proportional to 1/M 2 , with M denoting the nucleon mass. The nuclear spin-orbit potential corresponding to scalar and vector meson exchange is therefore obviously a truly relativistic effect. However, the quadratic reciprocal scaling of the spin-orbit NN-amplitude with the nucleon mass M is not universal, and it changes if one considers the exchange of two mesons between nucleons, i.e. loop diagrams. For example, irreducible two-pion exchange gives rise to a spin-orbit term in the NN T-matrix proportional to 1/M (see eqs. (22,23) in ref. [6]) and iterated one-pion exchange produces a spin-orbit term in the NN T-matrix which even scales linearly with the nucleon mass M (see eq.(33) in ref. [6]).In a recent work [7] we have used the systematic framework of chiral perturbation theory to calculate the nuclear spin-orbit interaction generated by one-and two-pion exchange. The momentum and density dependent nuclear spin-orbit strength U ls (p, k f ) is derived from the spindependent part of the interaction energy Σ spin = i 2 σ · ( q × p ) U ls (p, k f ) of a nucleon ...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Note the similarity of the expressions eqs. (8,9,10) with the three-body isovector single-particle potentials written in eqs. (30,31,32) of ref.…”

Section: Introductionmentioning

confidence: 99%

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Isovector nuclear spin–orbit interaction from chiral pion–nucleon dynamics

Kaiser

2003

Nuclear Physics A

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Radiopaques

Peng

2003

Burger's Medicinal Chemistry and Drug Discovery

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This review discusses radiopaques from research and development to application. Radiopaques attenuate X‐rays and may be either high atomic‐numbered materials or iodinated organic compounds. The latter may appear sometimes in liposomes or particulates. The theoretical and historical aspects, classification by structures, methods of synthesis, structure‐activity relationship, physical, chemical, and pharmacological properties, and related reactions, essential to the understanding of safety, tolerability, and efficacy of radiopaques in medical use, are included in the discussion.

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Nuclear spin–orbit interaction from chiral pion–nucleon dynamics

Kaiser

2002

Nuclear Physics A

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Using the two-loop approximation of chiral perturbation theory, we calculate the momentum and density dependent nuclear spin-orbit strength U ls (p, k f ). This quantity is derived from the spin-dependent part of the interaction energy Σ spin = i 2 σ ·( q × p ) U ls (p, k f ) of a nucleon scattering off weakly inhomogeneous isospin symmetric nuclear matter. We find that iterated 1π-exchange generates at saturation density, k f 0 = 272.7 MeV, a spinorbit strength at p = 0 of U ls (0, k f 0 ) ≃ 35 MeVfm 2 in perfect agreement with the empirical value used in the shell model. This novel spin-orbit strength is neither of relativistic nor of short range origin. The potential V ls underlying the empirical spin-orbit strength U ls = V ls r 2 ls becomes a rather weak one, V ls ≃ 17 MeV, after the identification r ls = m −1 π as suggested by the present calculation. We observe however a strong p-dependence of U ls (p, k f 0 ) leading even to a sign change above p = 200 MeV. This and other features of the emerging spin-orbit Hamiltonian which go beyond the usual shell model parametrization leave questions about the ultimate relevance of the spin-orbit interaction generated by 2π-exchange for a finite nucleus. We also calculate the complex-valued isovector singleparticle potential U I (p, k f )+i W I (p, k f ) in isospin asymmetric nuclear matter proportional to τ 3 (N − Z)/(N + Z). For the real part we find reasonable agreement with empirical values and the imaginary part vanishes at the Fermi-surface p = k f . : 12.38.Bx, 21.65.+f, 24.10.Cn Keywords: Effective field theory at finite density, Nuclear spin-orbit interaction, Complex single-particle potential in isospin asymmetric nuclear matter. PACS

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Kernmaterie — ein ungewöhnlicher Stoff

Abstract: 57 (1966) 248

Cited by 3 publications

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Isovector nuclear spin–orbit interaction from chiral pion–nucleon dynamics

Isovector nuclear spin–orbit interaction from chiral pion–nucleon dynamics

Radiopaques

Nuclear spin–orbit interaction from chiral pion–nucleon dynamics

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