Holographic Conductivity from Bulk Torsion in Riemann-Cartan Gravity
Standard gauge/gravity (AdS/CFT) duality uses a pseudo-Riemannian bulk with vanishing torsion. This work places an Abelian gauge field, dual to a boundary U(1) current, in a five-dimensional Chern-Simons gravity bulk whose Riemann-Cartan geometry carries non-trivial torsion, and computes in the probe limit how that torsion - which sources a boundary spin current - modifies the electrical conductivity of the boundary theory. Comparing the standard minimal coupling with several non-minimal torsion-electromagnetic couplings drawn from the literature, it finds the non-minimal couplings are better candidates for a holographic account of experimentally observed conductivity.
Riemann-Cartan holography and conductivity Duˇsan -Dord¯evi´c, Ivana -Dord¯evi´c, Aleksandra
Gauge/gravity (AdS/CFT) duality normally uses a pseudo-Riemannian bulk spacetime with vanishing torsion. This paper instead places an Abelian bulk gauge field, dual to a boundary U(1) current, in a f…