Constraints on nuclear-matter properties from QCD susceptibilities

2008

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We present a relativistic chiral effective theory for symmetric and asymmetric nuclear matter taken in the Hartree-Fock scheme. The nuclear binding is insured by a background chiral invariant scalar field associated with the radial fluctuations of the chiral quark condensate. Nuclear matter saturation is obtained once the scalar response of the nucleon generating three-body repulsive forces is incorporated. For these parameters related to the scalar sector and quark confinement mechanism inside the nucleon we make use of an analysis of lattice results on the nucleon mass evolution with the quark mass. The other parameters are constrained as most as possible by standard hadron and nuclear phenomenology. Special attention is paid to the treatment of the propagation of the scalar fluctuations. The rearrangement terms associated with in-medium modified mass and coupling constants are explicitly included to satisfy the Hugenholtz -Van Hove theorem. We point out the important role of the tensor piece of the rho exchange Fock term to reproduce the asymmetry energy of nuclear matter. We also discuss the isospin dependence of the Landau nucleon effective mass.

Section: Discussionmentioning

confidence: 99%

Section: B Nucleon Structure Effects and Confinement Mechanismmentioning

confidence: 99%

Relativistic chiral Hartree-Fock description of nuclear matter with constraints from nucleon structure and confinement

Massot

2008

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“…The origin of this failure can be attributed to the neglect of the effect of nucleon substructure linked to the confinement mechanism as already pointed out in some of our previous works [1,2,9]. It was demonstrated that nuclear matter stability can be restored once the scalar response of the nucleon depending on the quark confinement mechanism is properly incorporated in a way inspired from the QMC model [10].…”

Section: Introductionmentioning

confidence: 87%

Relativistic calculation of the pion loop correlation energy in nuclear matter in a theory including confinement

Massot

2009

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14 pages, 4 figures, submitted to Phys. Rev. CWe present a relativistic calculation of the saturation properties of nuclear matter which contains the correlation energy. Pion loops are incorporated on top of a relativistic Hartree-Fock (RHF) approach based on a chiral theory. It includes the effect of nucleon structure through its response to the background chiral invariant scalar field. All the parameters which enter the RHF calculation are fixed or strongly constrained by hadron phenomenology or lattice data. The new input for the correlation energy is the Landau-Migdal parameter g′ governing the short-range part of the spin-isospin interaction. We find that the inclusion of the correlation energy improves the description of the saturation properties of nuclear matter

“…In a previous work [22] we have introduced a model of a nucleon made of three constituent quarks bound together by a confining harmonic force. The magnitude of the scalar response which followed was too small to prevent the collapse of nuclear matter.…”

Section: Effect Of Confinement: Simple Models For the In-medium mentioning

confidence: 99%

Scalar fields in nuclear matter: The roles of spontaneous chiral symmetry breaking and nucleon structure

Ericson

2011

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Chiral theories with spontaneous symmetry breaking such as the Nambu-Jona-Lasinio (NJL) model lead to the existence of a scalar mode. We present in a detailed manner how the corresponding low-momentum effective Lagrangian involving the scalar field can be constructed starting from the NJL model. We discuss the relevance of the scalar mode for the problem of nuclear binding and saturation. We show that it depends on the nucleon mass origin with two extreme cases. If this origin is entirely due to confinement, the coupling of this mode to the nucleons vanishes, making it irrelevant for the nuclear binding problem. If instead it is entirely due to spontaneous symmetry breaking, it couples to the nucleons but nuclear matter collapses. It is only in the case of a mixed origin with spontaneous breaking that nuclear matter can be stable and reach saturation. We describe models of nucleon structure where this balance is achieved. We also show how chiral constraints and confinement modify the QCD sum rules for mass evolution in nuclear matter.