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Abstract
摘要 |
In the undoped state, the cuprates exhibit an optical conductivity that is featureless at frequencies less than 1eV. By contrast the doped state exhibits low-energy and mid-infrared features whose integrated intensity exceeds the number of dopant carriers as would be anticipated for doping a semiconductor. This excess intensity can only be understood if one invokes an effective high-low-energy mixing and hence the number of low-energy degrees of freedom is dictated by the high-energy scale. I will review how such mixing is expected from doping the Hubbard model and the modern attempts to understand the mid-infrared power law based on holography and a scale-invariant sector termed unparticles. I will show that within holographic gravitational crystals, no power-law scaling of the optical conductivity obtains in the mid-infrared regime. Within an unparticle construction, I show how such power laws can be produced. The key feature here is a large anomalous dimension. I will discuss how such large anomalous dimensions arise from UV-IR mixing. |
