Two-pion exchange and chiral symmetry restoration

Birse, Michael C.

doi:10.1103/physrevc.49.2212

Cited by 29 publications

(25 citation statements)

References 48 publications

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“…This point was emphasized in several works, see, e.g., Refs. [12,27]. Accordingly the link between our nuclear scalar field and QCD does not occur through the total nucleon sigma commutator but only through part of it, its nonpionic piece.…”

Section: Influence Of the Correlation Termmentioning

confidence: 99%

QCD susceptibilities and nuclear matter saturation in a chiral theory: Inclusion of pion loops

Chanfray

Ericson

2007

Phys. Rev. C

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We derive the equation of state of symmetric nuclear matter in a relativistic theory with σ and ω exchange. We take a chiral version of this model which insures all the chiral constraints. Going beyond the mean field approach we introduce the effects of the pion loops. For the parameters of the model, in order to fix those linked to pion exchange, we exploit the most recent information on the short-range part of the spin-isospin interaction. For those linked to the scalar meson exchange we make use of an analysis of lattice results on the nucleon mass evolution with the quark mass. With these inputs we are able reach a correct description of the saturation properties. From the equation of state of symmetric nuclear matter we also derive the density dependence of the quark condensate and of the QCD susceptibilities.

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Section: Influence Of the Correlation Termmentioning

confidence: 99%

QCD susceptibilities and nuclear matter saturation in a chiral theory: Inclusion of pion loops

Chanfray

Ericson

2007

Phys. Rev. C

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“…In the mean field approximation where pion loops are ignored this term does not appear. The other one, Q s S , arises from the scalar meson [6,7,8]. It is linear in the σ field :…”

Section: Study In a Nuclear Chiral Modelmentioning

confidence: 99%

Constraints on nuclear-matter properties from QCD susceptibilities

Ericson

Chanfray

2007

Eur. Phys. J. A

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We establish the interrelation between the QCD scalar response of the nuclear medium and its response to a scalar probe coupled to nucleons, such as the scalar meson responsible for the nuclear binding. The relation that we derive applies at the nucleonic as well as at the nuclear levels. Non trivial consequences follow. In particular it opens the possibility of relating medium effects in the scalar meson exchange or three-body forces of nuclear physics to QCD lattice studies of the nucleon mass.

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“…There have also been questions about whether the effect is sufficiently short-ranged that the hard-core correlations between nucleons mean that one nucleon does not feel the change in the condensate produced by its neighbours [13]. However, the strong coupling of a scalar meson, which can be interpreted as an excitation of the condensate, to two-pion states suggests that the effect should be long-ranged and so not cut out by the correlations [16].…”

mentioning

confidence: 99%

“…This would imply the existence of a scalar piece of the NN interaction that was proportional to σ πN /m 2 π at zero momentum transfer [16]. The chiral expansion of σ πN has the form [17] …”

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confidence: 99%

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What does a change in the quark condensate say about restoration of chiral symmetry in matter?

Birse

1996

Phys. Rev. C

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The contribution of nucleons to the quark condensate in nuclear matter includes a piece of first order in m π , arising from the contribution of lowmomentum virtual pions to the πN sigma commutator. Chiral symmetry requires that no term of this order appears in the N N interaction. The mass of a nucleon in matter thus cannot depend in any simple way on the quark condensate alone. More generally, pieces of the quark condensate that arise from low-momentum pions should not be associated with partial restoration of chiral symmetry.There has been much recent interest in the question of whether chiral symmetry is partially restored in nuclear matter.1 The chiral isospin symmetry SU(2)×SU (2) is an approximate symmetry of the QCD Lagrangian, broken only by the small current masses of the up and down quarks. This symmetry is realised in the hidden (spontaneously broken) mode since the QCD vacuum is not invariant under it. The scalar density of quarks, often referred to as the "quark condensate," provides an order parameter describing the hidden symmetry. Any reduction of this condensate in matter has generally been interpreted as a signal of partial restoration of the symmetry.1 For reviews of this topic and further references, see [1][2][3].

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Two-pion exchange and chiral symmetry restoration

Cited by 29 publications

References 48 publications

QCD susceptibilities and nuclear matter saturation in a chiral theory: Inclusion of pion loops

QCD susceptibilities and nuclear matter saturation in a chiral theory: Inclusion of pion loops

Constraints on nuclear-matter properties from QCD susceptibilities

What does a change in the quark condensate say about restoration of chiral symmetry in matter?

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