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Where the Nuclear Pions are  [PDF]
G. E. Brown,M. Buballa,Zi Bang Li,J. Wambach
Physics , 1994, DOI: 10.1016/0375-9474(95)00330-4
Abstract: Three recent experiments, which looked at pionic effects in nuclei have concluded that there are no excess pions. This puts into serious question the conventional meson-exchange picture of the nucleon-nucleon interaction. Based on arguments of partial restoration of chiral symmetry with density we propose a resolution to this problem.
Restoration of Chiral Symmetry from a Boundary  [PDF]
Brian C. Tiburzi
Physics , 2013,
Abstract: The imposition of Dirichlet boundary conditions in lattice computations obstructs the formation of a chiral condensate. We use chiral perturbation theory and meson models to address the effect of a Dirichlet boundary on chiral symmetry breaking. While pions are the longest-range modes in QCD, the restoration of chiral symmetry due to a boundary is shown not to depend upon the pion Compton wavelength but rather on that of the sigma meson. Power-law finite size corrections are exposed, and require prohibitively large lattices to overcome. We further speculate on the frustration of the chiral condensate for the case of confinement to the surface of a sphere.
Correlator mixing and mass reduction as signals of chiral symmetry restoration  [PDF]
J. Delorme,M. Ericson,P. A. M. Guichon,A. W. Thomas
Physics , 1999, DOI: 10.1103/PhysRevC.61.025202
Abstract: Chiral symmetry restoration in a dense medium is to some extent a consequence of the nuclear pion cloud. These pions induce a mixing of the axial and vector current contributions in the axial and vector correlators. We discuss their influence on hadron masses and investigate the signal produced by the remaining contribution associated with chiral symmetry restoration. Using the quark-meson coupling model we find that the latter is associated with the reduction of hadron masses.
Chiral symmetry restoration in excited hadrons  [PDF]
L. Ya. Glozman
Physics , 2003, DOI: 10.1063/1.1799788
Abstract: The evidence, theoretical justification and implications of chiral symmetry restoration in excited hadrons are presented.
Thermal and Nonthermal Pion Enhancements with Chiral Symmetry Restoration  [PDF]
P. Zhuang,Z. Yang
Physics , 2000, DOI: 10.1103/PhysRevD.63.016004
Abstract: The pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2pion to the lowest order in a 1/N_c expansion is calculated as a function of temperature T and chemical potential mu. The thermal and nonthermal enhancements of pions generated by the decay before and after the freeze-out present only in the crossover region of the chiral symmetry transition. The strongest nonthermal enhancement is located in the vicinity of the endpoint of the first-order transition.
Low-momentum Pion Enhancement Induced by Chiral Symmetry Restoration  [PDF]
Pengfei Zhuang
Physics , 2003, DOI: 10.1142/S0217751X04016490
Abstract: The thermal and nonthermal pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated. The nonthermal decay into pions of sigma mesons which are popularly produced in chiral symmetric phase leads to a low-momentum pion enhancement as a possible signature of chiral phase transition at finite temperature and density.
Chiral symmetry restoration in hadron spectra  [PDF]
L. Ya. Glozman
Physics , 2002, DOI: 10.1016/S0146-6410(03)00017-6
Abstract: The evidence and the theoretical justification of chiral symmetry restoration in high-lying hadrons is presented.
On the Thermodynamics of Chiral Symmetry Restoration  [PDF]
L. Burakovsky,L. P. Horwitz
Physics , 1996,
Abstract: The formulas for the temperature dependences of the non-strange and strange quark condensates are derived by taking into account the contribution of the massive resonances. Critical temperature of the chiral symmetry restoration transition is established to be 190 MeV if only meson resonances are considered, and 175 MeV if both meson and baryon resonances are taken into account.
What does a change in the quark condensate say about restoration of chiral symmetry in matter?  [PDF]
Michael C. Birse
Physics , 1996, DOI: 10.1103/PhysRevC.53.R2048
Abstract: The contribution of nucleons to the quark condensate in nuclear matter includes a piece of first order in $m_\pi$, arising from the contribution of low-momentum virtual pions to the $\pi N$ sigma commutator. Chiral symmetry requires that no term of this order appears in the $NN$ 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.
Restoration of chiral symmetry in excited hadrons  [PDF]
L. Ya. Glozman
Physics , 2004,
Abstract: Physics of the low-lying and high-lying hadrons in the light flavor sector is reviewed. While the low-lying hadrons are strongly affected by the spontaneous breaking of chiral symmetry, in the high-lying hadrons the chiral symmetry is restored. A manifestation of the chiral symmetry restoration in excited hadrons is a persistence of the chiral multiplet structure in both baryon and meson spectra. Meson and baryon chiral multiplets are classified. A relation between the chiral symmetry restoration and the string picture of excited hadrons is discussed.
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