The quenched gA puzzle in nuclei and nuclear matter and "pseudo-conformality" in QCD.

The long-standing puzzle of the quenched g A in nuclei is shown to have an extremely simple resolution in a renormalization-group (RG) treatment of a hidden local symmetric (HLS) and scale-symmetric (HSS) chiral Lagrangian. It is shown that the Landau–Migdal fixed-point approximation in nuclear matter (or V lowk in finite nuclei) in RG approach to strong correlations of fermionic hadrons on the Fermi surface exactly reproduces the superallowed Gamow–Teller transitions in the "Extreme Single-Particle (shell-)Model (ESPM)" in doubly-magic closed shell nuclei. One arrives at the quenching factor q ≈ 0. 7 8 giving the quenched g A eff ≈ 1. This resolution exposes scale-chiral symmetry, hidden in QCD in the vacuum, emerging in nuclear matter from low density to high compact-star density. It has important implications on "first principles" approaches to nuclear physics, such as the role of multi-body exchange currents in weak axial-current matrix elements in nuclei and in neutrinoless double β decays for going Beyond the Standard Model. This resolution could put in serious doubt the most recent improved measurement of the superallowed Gamow–Teller transition in the doubly-magic closed shell nucleus 1 0 0 Sn which if confirmed would require a "fundamental quenching" q ssb ∼ 1 ∕ 2. [ABSTRACT FROM AUTHOR]