Search

This brief note is to point out that the recent measurements at GSI and RIKEN of the superallowed Gamow-Teller transition in the doubly magic closed-shell nucleus $^{100}$Sn could give an indication for a possibly important {\it fundamental} quenching, thus-far unrecognized, of $g_A$, unambiguously distinct from nuclear correlation effects in the framework of nuclear effective field theory. The result, either confirmed or ruled out both experimentally and theory, can have strong impacts on nuclear physics vis-\`a-vis with nuclear effective field theory as well as on particle physics relevant for going beyond the Standard Model., Comment: Revised and prepared for invited paper

The possible consequence of an IR fixed point in QCD for $N_f=2, 3$ in nuclear matter is discussed. It is shown in terms of d(ilaton)-$\chi$ effective field theory (d$\chi$EFT) incorporated in a generalized effective field theory (G$n$EFT) implemented with hidden local symmetry and hidden scale symmetry that the recently measured superallowed Gamow-Teller transition in the doubly-magic-shell nucleus $^{100}$Sn indicates a surprisingly large anomaly-induced quenching (AIQ) of $g_A$ from the free-space value of 1.276 to $\approx 0.8 $. Combined with the quenching expected from strong nuclear correlations, the effective coupling in nuclei, $g_A^{\rm eff}$ would come to $\sim 1/2$. If this result were reconfirmed, it would impact not only nuclear structure and dense compact-star matter -- where $g_A$ figures in $\pi$-N coupling via the Goldberger-Treiman relation -- but also in search for physics Beyond the Standard Model (BSM), e.g. $0\nu\beta\beta$ decay, where 4th power of $g_A$ figures., Comment: 7 pages, no figures; typos corrected

The $V_{lowk}$-renormalization group approach on the surface of Fermi liquid for nuclear matter to which Tom Kuo made a pioneering contribution at Stony Brook is found to inject the pivotal input in the formulation of the generalized nuclear effective field theory with acronym ``G$n$EFT" applicable to superdense compact-star physics. A topology change in terms of skyrmions and half-skyrmions is shown to play the role of the ``putative" hadron-quark continuity (HQC)" conjectured in QCD. Crucially involved are hidden local symmetry (``HLS") and hidden scale symmetry (``HSS") with the vacuum sliding with density in nuclear medium, with the nuclear tensor force emerging as a Landau Fermi-liquid fixed-point quantity. A possibly novel paradigm, a ``Cheshire Catism," in nuclear correlations is suggested., Comment: 19 pages, 3 figures. Expanded with an additional author in tribute to Tom Kuo

The dense compact star matter is studied by using the skyrmion crystal approach. The chiral effective theory used includes the lightest scalar meson, the lowest-lying vector mesons as well as pions. Consistency with the vector manifestation and the dilaton limit fixed point at high density constrains the anomalous dimension of the gluon field $1.0 \lesssim |\gamma_{G^2}| \lesssim 2.0$ and leads to the significance of the scale symmetry breaking in the intrinsic parity-odd part of the effective theory. The speed of sound $v_s^2 \simeq 1/3$ and the polytropic index $\gamma \simeq 1$ -- both satisfy the conformal limits -- after the dilaton limit fixed point at high density but the matter is still in the hadronic phase. This means that neither the conformal speed of sound nor the smallness of the polytropic index can be used as a criterion of the onset of quark matter. These conclusions are significant for constructing the equation of state of nuclear matter., Comment: 6 pages, 5 figures