Quantum critical charge response from higher derivatives: is more different?

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We present new possibilities for the charge response in the quantum critical regime in 2+1D using holography, and compare them with field theory and recent quantum Monte Carlo results.

• We show that a family of (infinitely many) higher derivative terms in the gravitational bulk leads to behavior far richer than what was previously obtained.
• For example, we prove that the conductivity becomes unbounded, undermining previously obtained constraints.
• We further find a non-trivial and infinite set of theories that have a self-dual conductivity.