Diquark condensation and the quark-quark interaction

Bloch, Jacques; Roberts, Craig D.; Schmidt, S.

doi:10.1103/physrevc.60.065208

Cited by 87 publications

(122 citation statements)

References 30 publications

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“…This is indicated, too, by the ratio of charge radii; viz., r 0 + /r π = 1.08, which may be compared to the value of 1.09 obtained in Ref. [41] and contrasted with the value of 0.8 in [92]. In the absence of the scalar-diquark Bethe-Salpeter amplitude's pseudovector component, F qq 0 + ≡ 0, we find r 0 + = 0.51 fm; i.e., an increase of 6%.…”

Section: ρ-π Transition Form Factormentioning

confidence: 77%

πandρmesons, and their diquark partners, from a contact interaction

et al. 2011

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We present a unified Dyson-Schwinger equation treatment of static and electromagnetic properties of pseudoscalar and vector mesons, and scalar and axial-vector diquark correlations, based upon a vector-vector contact-interaction. A basic motivation for this study is the need to document a comparison between the electromagnetic form factors of mesons and those diquarks which play a material role in nucleon structure. A notable result, therefore, is the large degree of similarity between related meson and diquark form factors. The simplicity of the interaction enables computation of the form factors at arbitrarily large spacelike-Q 2 , which enables us to expose a zero in the ρ-meson electric form factor at z, where rρ, rD are, respectively, the electric radii of the ρ-meson and deuteron.

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Section: ρ-π Transition Form Factormentioning

confidence: 77%

πandρmesons, and their diquark partners, from a contact interaction

et al. 2011

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“…in rough agreement with our results. Figure 2 shows several model calculations and fits for the form factor ratio [21,23,24,25,26,27,28,29,30,31,32,33], which are seen to vary greatly. Improved experiments [8] would be able to distinguish these diverse approaches, and more fundamentally, better determine the value of (R * 2 M − R * 2 E ).…”

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confidence: 99%

Proton Electromagnetic-Form-Factor Ratios at LowQ2

2008

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We study the ratio R ≡ µG E (Q 2 )/G M (Q 2 ) of the proton at very small values of Q 2 . Radii commonly associated with these form factors are not moments of charge or magnetization densities. We show that the form factor F 2 is correctly interpretable as the two-dimensional Fourier transformation of a magnetization density. A relationship between the measurable ratio and moments of true charge and magnetization densities is derived. We find that existing measurements show that the magnetization density extends further than the charge density, in contrast with expectations based on the measured reduction of R as Q 2 increases.PACS numbers: 13.40.-f,13.40.Em,13.40.Gp,13.60.-r,14.20.Dh Keywords: form factors, charge densities Electromagnetic form factors of the proton and neutron (nucleon) are probability amplitudes that the nucleon can absorb a given amount of momentum and remain in the ground state, and therefore should determine the nucleon charge and magnetization densities. Much experimental technique, effort and ingenuity has been used recently to measure these quantities [1,2].The text-book interpretation of electromagnetic form factors, G E , G M , explained in [2], is that their Fourier transforms are measurements of charge and magnetization densities, and conventional wisdom relates the charge and magnetization mean square radii to the slopes of G E,M at Q 2 = 0. However, this interpretation is not correct because the wave functions of the initial and final nucleons have different momenta and therefore differ, invalidating a probability or density interpretation. A proper charge density is related to the matrix element of an absolute square of a field operator.Here we show that the proper magnetization density is the two-dimensional Fourier transform of the F 2 form factor. We use this and the result that the charge density is the two-dimensional Fourier transform of the F 1 form factor [3,4,5,6] to show that the magnetization density of the proton extends significantly further than its charge density. This is surprising because the observed rapid decrease of the ratio of electric to magnetic form factors with increasing values of Q 2 [1, 2] might lead one to conclude that the charge radius is larger than the magnetization radius.Form factors are matrix elements of the electromagnetic current operator J µ (x ν ) in units of the proton charge:

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“…Therefore, it has been adressed in various approaches like analytic continuation methods at high temperature and low density [12,13,14], chiral effective theories [15,16,17,18,19,20,21,22,23,24,25,26,27,28], (Polyakov-)Nambu-Jona-Lasinio or (Polyakov-)Quark-Meson(-Diquark) models [29,30,31,32,33,34,35,36,37,38,39], Dyson-Schwinger equations [40] and lattice gauge theory [41,42,43,44,45,46,47,5,6,48]. From these studies a conjectured phase diagram in the (µ, T ) plane has emerged.…”

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confidence: 99%

Phase transitions and gluodynamics in 2-colour matter at high density

et al. 2013

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Abstract. We investigate 2-colour QCD with 2 flavours of Wilson fermion at nonzero temperature T and quark chemical potential µ, with a pion mass of 700 MeV (mπ/mρ = 0.8). From temperature scans at fixed µ we find that the critical temperature for the superfluid to normal transition depends only very weakly on µ above the onset chemical potential, while the deconfinement crossover temperature is clearly decreasing with µ. We find indications of a region of superfluid but deconfined matter at high µ and intermediate T . The static quark potential determined from the Wilson loop is found to exhibit a 'string tension' that increases at large µ in the 'deconfined' region. The electric (longitudinal) gluon propagator in Landau gauge becomes strongly screened with increasing temperature and chemical potential. The magnetic (transverse) gluon shows little sensitivity to temperature, and exhibits a mild enhancement at intermediate µ before becoming suppressed at large µ.PACS. 11.15Ha Lattice gauge theory -12.38Aw Lattice QCD calculations -21.65Qr Quark matter -12.38Mh Quark-gluon plasma

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Diquark condensation and the quark-quark interaction

Cited by 87 publications

References 30 publications

πandρmesons, and their diquark partners, from a contact interaction

πandρmesons, and their diquark partners, from a contact interaction

Proton Electromagnetic-Form-Factor Ratios at LowQ2

Phase transitions and gluodynamics in 2-colour matter at high density

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