Chiral Symmetry Restoration and Parity Mixing

Abstract

We derive the expressions of the vector and axial current from a chiral Lagrangian restricted to nucleons and pions. They display mixing terms between the axial and vector currents. We study the modifications in the nuclear medium of the coupling constants of the axial current, namely the pion decay constant and the nucleonic axial one due to the requirements of chiral symmetry. We express the renormalizations in terms of the local scalar pion density. The latter also governs the quark condensate evolu- tion and we discuss the link between this evolution and the renormaliza- tions. In the case of the nucleon axial coupling constant this renormali- zation corresponds to a new type of exchange currents, with two exchanged pions. We give an estimate for the resulting quenching. Although moderate it helps explaining the quenching experimentally observed.

Latex, 15 pages. Several references and one figure added. New discussion of some points has been included. Treatment of the renormali- zation of the nucleon axial coupling constant has been developed

References in corpus (4)

• Dilepton and Photon Emission Rates from a Hadronic Gas
• Chiral Lagrangians and Quark Condensate in Nuclei
• What does a change in the quark condensate say about restoration of chiral symmetry in matter?
• The quark condensate at finite temperature

Cited by in corpus (15)

• e+e--pair production in Pb-Au collisions at 158 GeV per nucleon
• Is Rho-Meson Melting Compatible with Chiral Restoration?
• The $\rho$ Spectral Function in a Relativistic Resonance Model
• Vector and axial-vector correlators in a chirally symmetric model
• Dense Nuclear Matter: Landau Fermi-Liquid Theory and Chiral Lagrangian with Scaling
• The Quenching of the Axial Coupling in Nuclear and Neutron-Star Matter
• Chiral symmetry and quantum hadro-dynamics
• Scalar susceptibility and chiral symmetry restoration in nuclei
• In-medium modification of the isovector pion-nucleon amplitude
• Quantitative sum rule analysis of low-temperature spectral functions
• Gamow-Teller transitions and the spin EMC effect: the Bjorken sum-rule in medium
• Correlator mixing and mass reduction as signals of chiral symmetry restoration
• Anomaly-induced Chiral Mixing in Cold and Dense Matter
• Pion Scalar Density and Chiral Symmetry Restoration at Finite Temperature and Density
• Corrections to the Nuclear Axial Vector Coupling in a Nuclear Medium