Zero Sound from Holography

TL;DR

This paper investigates whether holographically dual theories exhibit zero sound modes similar to Fermi liquids, revealing a new class of quantum liquids with unique low-temperature properties.

Contribution

It demonstrates the presence of zero sound in holographic gauge theories with fundamental matter, indicating a novel type of quantum liquid beyond traditional Fermi liquids.

Findings

Zero sound mode found in holographic models.

Systems show non-Fermi liquid specific heat behavior.

Holography reveals a new quantum liquid class.

Abstract

Quantum liquids are characterized by the distinctive properties such as the low temperature behavior of heat capacity and the spectrum of low-energy quasiparticle excitations. In particular, at low temperature, Fermi liquids exhibit the zero sound, predicted by L. D. Landau in 1957 and subsequently observed in liquid He-3. In this paper, we ask a question whether such a characteristic behavior is present in theories with holographically dual description. We consider a class of gauge theories with fundamental matter fields whose holographic dual in the appropriate limit is given in terms of the Dirac-Born-Infeld action in AdS_{p+1} space. An example of such a system is the N=4 SU(N_c) supersymmetric Yang-Mills theory with N_f massless N=2 hypermultiplets at strong coupling, finite baryon number density, and low temperature. We find that these systems exhibit a zero sound mode despite having a non-Fermi liquid type behavior of the specific heat. These properties suggest that holography identifies a new type of quantum liquids.