# Effect of Curvature Squared Corrections to Gravitational Action on Viscosity-to-Entropy Ratio of the Dual Gauge Theory

 Title: Effect of Curvature Squared Corrections to Gravitational Action on Viscosity-to-Entropy Ratio of the Dual Gauge Theory Author: Petrov, Pavel Citation: Petrov, Pavel. 2012. Effect of Curvature Squared Corrections to Gravitational Action on Viscosity-to-Entropy Ratio of the Dual Gauge Theory. Doctoral dissertation, Harvard University. Access Status: Full text of the requested work is not available in DASH at this time (“dark deposit”). For more information on dark deposits, see our FAQ. Full Text & Related Files: Petrov_gsas.harvard_0084L_10549.pdf (423.8Kb; PDF) Abstract: In this thesis we study the properties of strongly-coupled large-N conformal ﬁeld theories (CFT’s) using AdS/CFT correspondence. Chapter 1 serves as an introduction. In Chapter 2 we study the shear viscosity of strongly-coupled large-N conformal ﬁeld theories. We find that it is affected by $$R^2$$ corrections to the AdS action and present an example of 4D theory in which the the conjectured universal lower bound on viscosity-to-entropy ratio $$\eta/s > 1/4 \pi$$ is violated by 1/N corrections. This fact proves that there is no universal lower bound of $$1/4 \pi$$ on viscosity-to-entropy ratio and may be relevant for the studies of QCD quark-gluon plasma for which this ratio is experimentally found to be close to $$1/4 \pi$$. In Chapter 3 we study the formation of the electron star in 4D AdS space. We show that in a gravity theory with charged fermions a layer of charged fermion fluid may form at a finite distance from the charged black hole. We show that these “electron stars” are candidate gravity duals for strongly interacting fermion systems at finite density and finite temperature. Entropy density for such systems scales as $$s \sim T^{2/z}$$ at low temperatures as expected from IR criticality of electron stars solutions. Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10368126 Downloads of this work:

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