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Universal fermionic spectral functions from string theory
Jerome P Gauntlett1, Julian Sonner, Daniel Waldram
1Theoretical Physics Group, Blackett Laboratory, Imperial College, London SW7 2AZ, United Kingdom.
Physical Review Letters
|January 17, 2012
Summary
This study presents the first holographic calculation of fermionic response functions in strongly coupled 3D systems. Surprisingly, the spectral function lacks a Fermi surface, revealing a phonino pole and power-law scaling governed by quantum criticality.
Area of Science:
- High-energy theoretical physics
- Quantum field theory
- String theory and holography
Background:
- Strongly coupled systems in 3 dimensions (d=3) are challenging to analyze using traditional methods.
- Holographic duality provides a powerful tool to study these systems via higher-dimensional supergravity (D=10 or D=11).
- Understanding fermionic behavior in such systems is crucial for condensed matter and high-energy physics.
Purpose of the Study:
- To perform the first holographic calculation of a fermionic response function for a strongly coupled d=3 system with a supergravity dual.
- To investigate the nature of the spectral function and its implications for the system's properties at finite charge density.
- To explore the connection between holographic calculations and quantum critical phenomena.
Main Methods:
- Employed holographic duality, specifically utilizing D=10 or D=11 supergravity duals.
- Calculated the fermionic response function by considering the supersymmetry current.
- Analyzed the resulting spectral function to identify key features like poles and scaling behaviors.
Main Results:
- Obtained a universal result for the fermionic response function applicable to all d=3 N=2 Superconformal Field Theories (SCFTs) with supergravity duals.
- Discovered that the spectral function surprisingly lacks a Fermi surface, even at finite charge density.
- Identified a phonino pole and observed a depletion of spectral weight at low frequencies, exhibiting power-law scaling governed by a local quantum critical point.
Conclusions:
- The holographic approach reveals non-trivial fermionic behavior in strongly coupled 3D systems, deviating from expectations based on Fermi surfaces.
- The presence of a phonino pole and quantum critical scaling suggests novel emergent phenomena in these holographic models.
- This work establishes a framework for studying fermionic properties in strongly coupled gauge theories via their gravitational duals.
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