A Non-Fermi Liquid from a Charged Black Hole; A Critical Fermi Ball

Understand

Using the AdS/CFT correspondence, we calculate a fermionic spectral function in a 2+1 dimensional non-relativistic quantum field theory which is dual to a gravitational theory in the $AdS_4$ background with a charged black hole.

• The spectral function shows no quasiparticle peak but the Fermi surface is still well defined.
• Interestingly, all momentum points inside the Fermi surface are critical and the gapless modes are defined in a {\it critical Fermi ball} in the momentum space.