Kaon Condensation in Baryonic Fermi Liquid at High Density

TL;DR

This paper formulates kaon condensation in dense baryonic matter using a Wilsonian RG approach, revealing that the critical density for condensation is significantly lower than previous chiral perturbation theory predictions.

Contribution

It introduces a Wilsonian RG framework for kaon condensation, contrasting with traditional chiral perturbation theory, and identifies the dominant interactions influencing the critical density.

Findings

Critical density is three times lower with the RG approach.

Scalar exchange dominates the relevant interaction.

Vector meson exchange contributes an irrelevant term.

Abstract

We formulate kaon condensation in dense baryonic matter with anti-kaons fluctuating from the Fermi-liquid fixed point. This entails that in the Wilsonian RG approach, the decimation is effectuated in the baryonic sector to the Fermi surface while in the meson sector to the origin. In writing the kaon-baryon (KN) coupling, we will take a generalized hidden local symmetry Lagrangian for the meson sector endowed with a "mended symmetry" that has the unbroken symmetry limit at high density in which the Goldstone $\pi$, scalar $s$, and vectors $\rho$ (and $\omega$) and $a_1$ become massless. The vector mesons $\rho$ (and $\omega$) and $a_1$ can be identified as emergent (hidden) local gauge fields and the scalar $s$ as the dilaton field of the spontaneously broken scale invariance at chiral restoration. In matter-free space, when the vector mesons and the scalar meson -- whose masses are much greater than that of the pion -- are integrated out, then the resulting KN coupling Lagrangian consists of the leading chiral order ($O(p^1)$) Weinberg-Tomozawa term and the next chiral order ($O(p^2)$) $\Sigma_{KN}$ term. In addressing kaon condensation in dense nuclear matter in chiral perturbation theory (ChPT), one makes an expansion in the "small" Fermi momentum $k_F$. We argue that in the Wilsonian RG formalism with the Fermi-liquid fixed point, the expansion is on the contrary in $1/k_F$ with the "large" Fermi momentum $k_F$. The kaon-quasinucleon interaction resulting from integrating out the massive mesons consists of a "relevant" term from the scalar exchange (analog to the $\Sigma_{KN}$ term) and an "irrelevant" term from the vector-meson exchange (analog to the Weinberg-Tomozawa term). It is found that the critical density predicted by the latter approach, controlled by the relevant term, is three times less than that predicted by chiral perturbation theory.