Nucleon core size and nuclear forces
TL;DR: In this article, the size of the quark core of nucleons was estimated by using a quark model of the nucleon-nucleon spin-orbit forces, with both one-gluon and ϱ-, ω-meson exchange qq interactions.
About: This article is published in Physics Letters B.The article was published on 1986-03-06. It has received 12 citations till now. The article focuses on the topics: Nuclear force & Nucleon.
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TL;DR: In this paper, a new fit to the world data on (ep) and (en) elastic scattering, and on (n) annihilation into lepton pairs, has been obtained by using a model for the isovector and isoscalar nucleon form factors, which is suggested by the use of unitary symmetry and of its breaking.
Abstract: SummaryA new fit to the world data on (ep) and (en) elastic scattering, and on (
$$\\bar p$$
p) annihilation into lepton pairs, has been obtained by using a model for the isovector and isoscalar nucleon form factors, which is suggested by the use of unitary symmetry and of its breaking. The fit allows for a nonpointlike behaviour of one out of the two couplings which enter in the expression for nucleon electromagnetic form factors. The fit is a one-parameter fit and the corresponding values ofχ2 for the proton and neutron data are discussed. The contributions coming from the possible existence of « core-terms » and of «q2-dependent background » in the expression of the nucleon electromagnetic form factors are found to be lower than a few per cent. Theq2 dependence of the vector-meson-nucleon couplings is also discussed.RiassuntoSi è ottenuta una nuova approssimazione ai dati universali sullo scattering elastico (ep) e (en) e sulla annichilazione (
$$\\bar p$$
p) in coppie di leptoni, facendo uso di un modello per i fattori di forma isovettoriali ed isoscalari del nucleone, suggerito dall’uso della simmetria unitaria e della sua infrazione. L’approssimazione tiene conto del comportamento non puntiforme di uno dei due accoppiamenti che entrano nell’espressione dei fattori di forma elettromagnetici del nucleone. L’approssimazione è ad un solo parametro e si discutono i corrispondenti valori di χ2 per i dati dei protoni e dei neutroni. Si trova che i contributi derivanti dalla possibile esistenza di « core terms » e di « un fondo dipendente da ϱ2 » nell’espressione dei fattori di forma elettromagnetici del nucleone sono inferiori ad alcuni percento. Si discute anche la dipendenza daq2 dell’accoppiamento mesone vettoriale-nucleone.
44 citations
TL;DR: In this article, the authors considered the coupling between heavy-light and heavy-heavy quarks induced by the instantons and their effects on the spin-dependent mass of the charmonia and their hyperfine mass splittings.
Abstract: The QCD vacuum is populated by instantons that correspond to the tunneling processes in the vacuum. This mechanism creates the strong vacuum gluon fields. As result, the QCD vacuum instantons induce very strong interactions between light quarks, initially almost massless. Such a strong interactions bring a large dynamical mass M of the light quarks and bound them to produce almost massless pions in accordance with the spontaneous breaking of the chiral symmetry (SBCS). On the other hand, the QCD vacuum instantons also interact with heavy quarks and responsible for the generation of the heavy-heavy and heavy-light quarks interactions, with a traces of the SBCS. If we take the average instanton size fm, and the average inter-instanton distance fm we obtain the dynamical light quark mass to be M = 365 MeV and the instanton media contribution to the heavy quark mass ΔM =70 MeV. These factors define the coupling between heavy-light and heavy-heavy quarks induced by the QCD vacuum instantons. We consider first the instanton effects on the heavy-heavy quarks potential, including its spin-dependent part. We also discuss those effects on the masses of the charmonia and their hyperfine mass splittings. At the second part we discuss the interaction between a heavy and light quarks generated by instantons and it’s effects.
7 citations
TL;DR: In this article, the influence of the instanton background on the heavy quark correlators was considered in the framework of instanton liquid model (ILM) of QCD vacuum by taking into account also the perturbative gluon effects.
Abstract: In the present work, we consider the influence on the heavy quark correlators due to the instanton background in the framework of instanton liquid model (ILM) of QCD vacuum by taking into account also the perturbative gluon effects. For a single heavy quark, this leads to the mass shift due to the direct-instanton nonperturbative and ILM modified perturbative contributions, respectively. In the heavy quark-antiquark ($Q\overline{Q}$) sector, we obtain the potential consisting the direct instanton induced part and the one-gluon exchange (OGE) perturbative part, which is screened at large distances due to the nonperturbative dynamics. At the region of interest corresponding to the heavy quark physics, the screening effect in OGE can be well approximated by a Yukawa-type potential in terms of the dynamically generated gluon mass. A possible implication of the present studies to the phenomenology of heavy quarkonium is also discussed.
6 citations
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TL;DR: In this paper, the P-wave spin-orbit mass splittings in Λ baryons were shown to be consistent with those of nonstrange Baryons in a naive quark model, but only by introducing additional terms in the quark-quark effective interaction.
5 citations
TL;DR: In this paper, it was shown that quark contributions to the charge dependence of the nucleon-nucleon scattering length a( 1 S 0 ) are primarily of electromagnetic origin and are sensitive only to the rms radius rc of the nucleus core of quarks.
4 citations
References
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TL;DR: In this article, the structure of the particle source in the classical theory is calculated, and some qualitative features of the interactions between these particles and mesons are described, and the way in which a non-linear meson field theory of this type may contain its own sources, and how these may be idealised to point singularities, as in the conventional field theories of interacting linear systems, is formulated.
1,975 citations
TL;DR: In this paper, the Paris $N\ensuremath{-}N$ potential is parametrized in a simple analytical form, which consists of a regularized discrete superposition of Yukawa-type terms.
Abstract: In view of practical nuclear structure calculations the Paris $N\ensuremath{-}N$ potential is parametrized in a simple analytical form. This parametrization consists of a regularized discrete superposition of Yukawa-type terms. Results for phase shifts and deuteron parameters are presented as well as nuclear matter binding energy obtained with this potential.NUCLEAR REACTIONS Nucleon-nucleon interaction, parametrization of the Paris $N\ensuremath{-}N$ potential. 0 to 330 MeV $N\ensuremath{-}N$ phase shifts.
797 citations
TL;DR: In this article, a new theory of strong interactions is proposed based on the notion of parity conservation in strong couplings, which is similar to the one proposed in this paper, but with three different types of couplings: hypercharge coupling, isospin coupling, and isobarsin coupling.
791 citations
TL;DR: In this paper, electron-nucleon form factors were determined from Rosenbluth plots and, independently, by fitting a dispersion ansatz to electron nucleon scattering cross sections, allowing for a renormalization of the data in both cases.
462 citations