$c$-Theorem for Anisotropic RG Flows from Holographic Entanglement Entropy
Chong-Sun Chu, Dimitrios Giataganas
TL;DR
The paper extends the holographic c-theorem to quantum field theories with broken Lorentz and rotational symmetry by defining anisotropic c-functions built from slab entanglement entropies in distinct directions. It derives the necessary and sufficient geometric conditions for monotonic RG flow, showing that null energy conditions alone are insufficient and that UV boundary data (and FG expansion data) can guarantee monotonicity for at least one of the anisotropic c-functions. The work provides explicit sufficient conditions, analyzes Lifshitz-like and hyperscaling-violation examples, and discusses necessary conditions and UV/IR boundary criteria. The framework broadens the applicability of entropic c-functions to anisotropic systems and offers tools for constructing monotonic RG flows in holographic models, with potential connections to F-theorem-like statements and nonlocal observables.
Abstract
We propose a candidate $c$-function in arbitrary dimensional quantum field theories with broken Lorentz and rotational symmetry. For holographic theories we derive the necessary and sufficient conditions on the geometric background for these $c$-functions to satisfy the $c$-theorem. We obtain the null energy conditions for anisotropic background to show that do not themselves assure the $c$-theorem. By employing them, we find that is possible to impose conditions on the UV data that are enough to guarantee at least one monotonic $c$-function along the RG flow. These UV conditions can be used as building blocks for the construction of anisotropic monotonic RG flows. Finally, we apply our results to several known anisotropic theories and identify the region in the parameters space of the metric where the $c$-theorem holds for our proposed $c$-function.
