Anomalous Dimensions and Unparticles in the Cuprate Superconductors

Speaker: 
Philip Phillips
Event Date and Time: 
Thu, 2016-03-10 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
George Sawatzky
Intended Audience: 
Graduate

High-temperature superconductivity in the cuprates remains an unsolved problem because no knock-down experiment has  revealed unambiguously the nature of the charge carriers in the normal state. I will show here that what is strange about the normal state is that the current for the underlying charge carriers possess an anomalous dimension.  To show this, I will focus on the optical conductivity.  Two features are problematic:  1) violation of the f-sum rule and 2) power-law scaling in the mid-infrared. So befuddling is the latter that even high-energy theorists have written papers on the puzzling ω-2/3 scaling law in the cuprates.  The key claim here is that the observed power law is a universal consequence of gravity in the presence of translational symmetry breaking. I will explain this claim and report on a calculation that tests it.  I will show that the general claim is not true.  As an alternative, I will show how unparticles or a scale invariant sector in the mid-infrared can account for the experimentally observed power law and a violation of the f-sum rule.  A feature of the unparticle construction is that they admit an anomalous dimension for the current.  I will show how an anomalous dimension can be constructed from massive gravity.  I will also show how anomalous dimensions can be experimentally probed by the fractional Aharonov- Bohm effect in the normal state of the cuprates.

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