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See detailQuark transverse charge densities in the Delta(1232) from lattice QCD
Alexandrou, Constantia; Korzec, Tomasz; Giannis, Koutsou et al

in Nuclear Physics A (2009), A825

We extend the formalism relating electromagnetic form factors to transverse quark charge densities in the light-front frame to the case of a spin-3/2 baryon and calculate these transverse densities for ... [more ▼]

We extend the formalism relating electromagnetic form factors to transverse quark charge densities in the light-front frame to the case of a spin-3/2 baryon and calculate these transverse densities for the $\Delta (1232)$ isobar using lattice QCD. The transverse charge densities for a transversely polarized spin-3/2 particle are characterized by monopole, dipole, quadrupole, and octupole patterns representing the structure beyond that of a pure point-like spin-3/2 particle.We present lattice QCD results for the $\Delta$-isobar electromagnetic form factors for pion masses down to approximatively 350 MeV for three cases: quenched QCD, two-degenerate flavors of dynamicalWilson quarks, and three flavors of quarks using a mixed action that combines domain wall valence quarks and dynamical staggered sea quarks. We extract transverse quark charge densities from these lattice results and find that the $Delta$ is prolately deformed, as indicated by the fact that the quadrupole moment $G_{E2}(0)$ is larger than the value −3 characterizing a point particle and the fact that the transverse charge density in a $\Delta^+$ of maximal transverse spin projection is elongated along the axis of the spin. [less ▲]

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See detailA Review of the hard pomeron in soft diffraction
Cudell, Jean-René ULg; Lengyel, Alexander; Martynov, Evgenij et al

in Nuclear Physics A (2005), 755

We review the evidence for the presence of a hard singularity in soft forward amplitudes, and give an estimate of its trajectory and couplings.

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See detailNucleon-nucleon interaction in a chiral constituent quark model
Bartz, Daniel ULg; Stancu, Floarea ULg

in Nuclear Physics A (2002), 699(1-2), 316-319

We study the nucleon-nucleon interaction within a chiral constituent quark model where the hyperfine interaction is due to pseudoscalar meson exchange. We calculate the S-3(1) and S-1(0) phase shifts by ... [more ▼]

We study the nucleon-nucleon interaction within a chiral constituent quark model where the hyperfine interaction is due to pseudoscalar meson exchange. We calculate the S-3(1) and S-1(0) phase shifts by using the resonating group method. Their behaviour clearly indicates the presence of a strong repulsive core at short distance. This is due to the spin-flavour symmetry of the interaction and to the quark interchange between the two interacting nucleons. We add a sigma-meson exchange quark-quark interaction which provides a medium range attraction necessary to describe the S-1(0) phase shift. We also explore the role of a tensor interaction at the quark level. [less ▲]

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See detailStability of strange quark matter in an effective chiral model with scale anomaly
Jaminon, Martine ULg; Van den Bossche, Bruno

in Nuclear Physics A (2001), 686

Stability of strange quark matter is investigated within a chiral model which implements the scale anomaly of QCD. As far as quark confinement is mimicked by a large value of the u-quark mass, the model ... [more ▼]

Stability of strange quark matter is investigated within a chiral model which implements the scale anomaly of QCD. As far as quark confinement is mimicked by a large value of the u-quark mass, the model behaves in the chiral limit as a MIT bag model: it yields a stable system composed of quarks surrounded by the vacuum. As soon as finite current quark masses are taken into account, stability is however lost. [less ▲]

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See detailStrong decays of the glueball in a scaled effective Lagrangian
Jaminon, Martine ULg; Mathot, Michel ULg; Van den Bossche, Bruno

in Nuclear Physics A (2000), 662

We calculate the scalar glueball decays into pipi, etaeta, etaeta' and KK within a modified version of the NJL model which implements the QCD trace anomaly. The glueball is assumed to be the f0(1500). It ... [more ▼]

We calculate the scalar glueball decays into pipi, etaeta, etaeta' and KK within a modified version of the NJL model which implements the QCD trace anomaly. The glueball is assumed to be the f0(1500). It is coupled to the quarks due to its mixing with the scalar isoscalar mesons. The decay widths then contain a contribution coming from the triangle Feynman diagram. Moreover, they contain two additional contributions corresponding to the local decay of the glue component of the f0(1500): one comes from the process of regularization of the quark loop, the other from the interaction term a2chi2phgr2. Except for the etaeta' case, this local decay reduces the value of the width. The axial anomaly is introduced via a mass term for the eta'. As far as the lightest scalar glueball is identified with the f0(1500), the model cannot reproduce at the same time the dynamical properties of scalars and pseudoscalars. Since we do not include a model of confinement, we need to use a large quark mass (725 MeV) in our calculations. This leads to unphysical results for the two-pion decay width. A definitive test of our model awaits the introduction of a model of confinement, which we hope to include in a future work. [less ▲]

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See detailTwo photon decay of the glueball and scalar isosclar mesons in a scaled NJL model
Jaminon, Martine ULg; Van den Bossche, Bruno

in Nuclear Physics A (1998), 636

We use a modified version of the Nambu-Jona-Lasinio (NJL) model which implements the QCD trace anomaly to calculate the two photon decay width of the glueball (f0(1500)) and of the two scalar mesons (f0 ... [more ▼]

We use a modified version of the Nambu-Jona-Lasinio (NJL) model which implements the QCD trace anomaly to calculate the two photon decay width of the glueball (f0(1500)) and of the two scalar mesons (f0(1370), fJ=0(1710)) to which it is mixed. We investigate the effect of the mixing over the coupling constants of the f0 states to the quarks and over the widths. We show that mass and phase space effects are crucial, at least in the NJL model, in determining the relative strength of the 2γ widths. [less ▲]

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See detailGluonic content of the scalar meson nonet in a scaled effective Lagrangian
Jaminon, Martine ULg; Van den Bossche, Bruno

in Nuclear Physics A (1997), 619

A scaled SU(3) Nambu-Jona-Lasinio Lagrangian is used to compute the mass of the nine scalar mesons in the vacuum and the mass of the glueball. This chiral model provides a gluonic content to the scalar ... [more ▼]

A scaled SU(3) Nambu-Jona-Lasinio Lagrangian is used to compute the mass of the nine scalar mesons in the vacuum and the mass of the glueball. This chiral model provides a gluonic content to the scalar mesons as well as a quark content to the glueball. It is shown that a suitable choice of the vacuum gluon condensate allows reproduction of the experimental masses of the scalar mesons except for K*0(1430). This choice corresponds to a weak coupling between the gluon and quark condensates, giving f0(1500) or fJ(1710) which is nearly a pure glueball. [less ▲]

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See detailPhase transition and thermodynamics of a hot and dense system in a scaled NJL model
Cugnon, Joseph ULg; Jaminon, Martine ULg; Van den Bossche, Bruno

in Nuclear Physics A (1996), 598

he chiral phase transition of a hot and dense system of quarks is studied within a modified SU(3) NJL Lagrangian that implements the QCD scale anomaly. The u- and s-quark condensates can or can not feel ... [more ▼]

he chiral phase transition of a hot and dense system of quarks is studied within a modified SU(3) NJL Lagrangian that implements the QCD scale anomaly. The u- and s-quark condensates can or can not feel the same chiral restoration depending on the considered region of the three-dimensional space (Tc, muuc, musc). The temperature behaviour of the pressure and the energy and entropy densities of the u- and s-quark system is investigated. At high temperature, the non-vanishing bare s-quark mass only modifies slightly the usual behaviour associated with an ideal quark gas. [less ▲]

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See detailAnomalous pion decay in effective QCD at finite temperature
Blaschke, David; Jaminon, Martine ULg; Kalinovsky, Yu. L. et al

in Nuclear Physics A (1995), 592

The width of the process π0 → γγ is calculated within effective QCD at finite temperature. We use two different effective models which describe chiral symmetry breaking and its restoration at finite ... [more ▼]

The width of the process π0 → γγ is calculated within effective QCD at finite temperature. We use two different effective models which describe chiral symmetry breaking and its restoration at finite temperature in SU(2)ƒ: (i) an effective lagrangian with a nonlocal separable interaction kernel, (ii) A- and B-scaledNJL lagrangians which implement the scale anomaly of QCD. We calculate the temperature dependences of the quark and pion masses as well as of the pion-park-antiquark coupling strength below and above the double quark mass threshold. At zero temperature we obtain a fairly good agreement with the experimental value for the decay width. The temperature dependence of the decay width is related to that of the pion mass. Γπ0 → γγ is enhanced in the vicinity of the Mott temperature (Mπ = 2mq) for the nonlocal as well as for the A-scaled model and suppressed for the B-scaled model. We compare our results with the SU(2) Nambu-Jona-Lasinio model which is contained as a limiting case in our approach. [less ▲]

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See detailSU (3) scaled effective lagrangians for a hot and strange system
Jaminon, Martine ULg; Van Den Bossche, Bruno

in Nuclear Physics A (1995), 582

We construct two effective lagrangians which reproduce the explicit flavor SU(3) symmetry breaking and the trace and axial anomalies of QCD. All analytical expressions are derived for a hot strange matter ... [more ▼]

We construct two effective lagrangians which reproduce the explicit flavor SU(3) symmetry breaking and the trace and axial anomalies of QCD. All analytical expressions are derived for a hot strange matter but the results are only shown for zero baryonic density. We study the coupling of the quark condensates (u and s) to the gluon condensate. We also consider the temperature behavior of the pion and of the kaon masses. We show that the results crucially depend on the choice of the two free parameters of the model: the chiral transition can be of first or of second order; the coupling between the gluon and the quark condensates can be large or not; the meson masses can increase or decrease with temperature. The introduction of the QCD trace anomaly in the SU(3) NJL model kills the predictive character of the NJL. [less ▲]

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See detailThe coupling of quark and gluon condensates in hot and dense systems
Jaminon, Martine ULg; Van den Bossche, Bruno

in Nuclear Physics A (1994), 567

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See detailChiral theory of mesons in dense baryonic matter (II) : Meson propagation
Jaminon, Martine ULg; Mendez Galain; Stassart, Pierre ULg

in Nuclear Physics A (1993), 556

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See detailScaled effective chiral lagrangians for the propagation of scalar and vector mesons in dense matter
Jaminon, Martine ULg; Ripka, Georges

in Nuclear Physics A (1993), 564

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See detailEffect of the vector-axial-vector coupling on the vector-meson modes
Jaminon, Martine ULg; Mendez Galain, Ramon

in Nuclear Physics A (1993), 564

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See detailChiral theory of mesons in dense baryonic matter (I)
Jaminon, Martine ULg; Mendez Galain, Ramon; Ripka, Georges et al

in Nuclear Physics A (1992), 537

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See detailChiral mesons in dense nuclear matter
Jaminon, Martine ULg; Ripka, Georges; Stassart, Pierre ULg

in Nuclear Physics A (1989), 504

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See detailEffect of correlations on the momentum distribution of protons in 208Pb
Jaminon, Martine ULg; Mahaux, Claude ULg; Ngô, Hélène

in Nuclear Physics A (1986), 452

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