Relativistic three-quark bound states in separable two-quark approximation

Oettel, Martin; Smekal, Lorenz von; Alkofer, Reinhard

doi:10.1016/s0010-4655(01)00465-9

Cited by 22 publications

(28 citation statements)

References 28 publications

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“…We solve the equations via the method described in Ref. [55]. The masses of the scalar and axial-vector diquarks are the only variable parameters.…”

Section: Nucleon and ∆ Massesmentioning

confidence: 99%

On Nucleon Electromagnetic Form Factors

et al. 2005

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Abstract. A Poincaré covariant Faddeev equation, which describes baryons as composites of confined-quarks and -nonpointlike-diquarks, is solved to obtain masses and Faddeev amplitudes for the nucleon and ∆. The amplitudes are a component of a nucleon-photon vertex that automatically fulfills the Ward-Takahashi identity for on-shell nucleons. These elements are sufficient for the calculation of a quark core contribution to the nucleons' electromagnetic form factors. An accurate description of the static properties is not possible with the core alone but the error is uniformly reduced by the incorporation of meson-loop contributions. Such contributions to form factors are noticeable for Q 2 2 GeV 2 but vanish with increasing momentum transfer. Hence, larger Q 2 experiments probe the quark core. The calculated behaviour of] GeV 2 agrees with that inferred from polarisation transfer data. Moreover, Q 2 F 2 (Q 2 )/F 1 (Q 2 ) ≈ constant on this domain. These outcomes result from correlations in the proton's amplitude. January 25, 2018

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“…We solve the equations via the method described in Ref. [55]. The masses of the scalar and axial-vector diquarks are the only variable parameters.…”

Section: Nucleon and ∆ Massesmentioning

confidence: 99%

On Nucleon Electromagnetic Form Factors

et al. 2005

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“…To solve the BS equations we use the algorithm introduced by Oettel et al [32] . The efficiency of this algorithm has already been reported in several publications, see for example Refs.…”

Section: A Numerical Methods For the Coupled Bs Equationsmentioning

confidence: 99%

“…It turns out that these tri-spinors can be written as linear combinations of the eight components defined in Eq. (32). Thus from knowledge of S i and A i , a full partial wave decomposition can be immediately obtained [29].…”

Section: Three-body Sectormentioning

confidence: 99%

“…In this paper we present our first results from a calculation of the relativistic Faddeev equation for a non-local NJL model, based on the covariant diquark-quark picture of baryons [24,25,26,27,28,29,30,31,32]. Such an approach has been extensively employed to study baryons in the local NJL model, see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

“…This makes it possible to adopt the numerical method developed for such problems in Refs. [29,30,31,32]. This paper is organised as follows: In Sec.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Baryon structure in a quark-confining nonlocal Nambu–Jona–Lasinio model

2004

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We study the nucleon and diquarks in a non-local Nambu-Jona-Lasinio model. For certain parameters the model exhibits quark confinement, in the form of a propagator without real poles. After truncation of the two-body channels to the scalar and axial-vector diquarks, a relativistic Faddeev equation for nucleon bound states is solved in the covariant diquark-quark picture. The dependence of the nucleon mass on diquark masses is studied in detail. We find parameters that lead to a simultaneous reasonable description of pions and nucleons. Both the diquarks contribute attractively to the nucleon mass. Axial-vector diquark correlations are seen to be important, especially in the confining phase of the model. We study the possible implications of quark confinement for the description of the diquarks and the nucleon. In particular, we find that it leads to a more compact nucleon.

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Electromagnetic Properties of Diquarks

Maris

2004

Few-Body-Systems

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Abstract. Diquark correlations play an important role in hadron physics. The properties of diquarks can be obtained from the corresponding bound state equation. Using a model for the effective quark-quark interaction that has proved successful in the light meson sector, we solve the scalar diquark Bethe-Salpeter equations and use the obtained Bethe-Salpeter amplitudes to compute the diquarks' electromagnetic form factors. The scalar ud diquark charge radius is about 8% larger than the pion charge radius, indicating that these diquarks are somewhat larger in size than the corresponding mesons. We also provide analytic fits for the form factor over a moderate range in Q 2 , which may be useful, for example, in building quark-diquark models of nucleons. DiquarksDiquarks are coloured states of two quarks. Due to their colour charge, they are expected to be confined, and cannot be observed directly. Despite being confined, they can play a role in the dynamics of baryons: two quarks in a colour anti-triplet configuration can couple with a third quark to form a colour singlet baryon. Indeed quark-diquark models have been used quite successfully in various models for baryons [1,2,3]. More recently, they also have been suggested as the constituents of pentaquarks: one could imagine a pentaquark as a bound state of two diquarks and an antiquark [4], or as a bound state of a diquark and a triquark [5].For calculations of the baryon spectrum within a quark-diquark model, the most important property of the diquarks is their mass. There are a number of different calculations of these masses available, both from lattice QCD [6] and using the set of Dyson-Schwinger equations [DSEs] [7,8,9]. These calculations seem to agree with each other to within about 20%. For calculations of electromagnetic properties of nucleons (and other baryons), one also needs to know how photons couple to diquarks. Since they are not observable, we cannot obtain *

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Relativistic three-quark bound states in separable two-quark approximation

Cited by 22 publications

References 28 publications

On Nucleon Electromagnetic Form Factors

On Nucleon Electromagnetic Form Factors

Baryon structure in a quark-confining nonlocal Nambu–Jona–Lasinio model

Electromagnetic Properties of Diquarks

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