Holographic zero sound for $\mathcal{N}=2$ SCFTs in 4d

TL;DR

This paper explores holographic models of four-dimensional $ ext{N}=2$ SCFTs at finite chemical potential, revealing gapless excitations, zero sound modes, and sector-dependent AC conductivities through correlation function analysis.

Contribution

It introduces the concept of metallic holography for $ ext{N}=2$ SCFTs, analyzing low-frequency correlation functions and identifying zero sound modes and sector-specific transport properties.

Findings

Identification of gapless excitations in the color sector.

Detection of zero sound modes with finite phase velocity.

Distinct AC conductivity behaviors for color and flavor sectors.

Abstract

We build up the notion of metallic holography for $\mathcal{N}=2$ SCFTs in four dimensions, in the presence of a finite $U(1)$ chemical potential. We compute two point correlation functions and study their properties in the regime of low frequency and low momentum. The color sector reveals gapless excitations, one of which propagates with a finite phase velocity while the other mode attenuates through scattering. The flavour sector, on the other hand, reveals spectrum that contains quasiparticle excitations which propagate with a definite phase velocity together with modes that propagate with a finite group velocity which quantum attenuates quite similar in spirit as that of Landau's zero sound modes. We also compute associated AC conductivities, which exhibit different characteristics for different (color and flavour) sectors of $\mathcal{N}=2$ SCFTs.