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**11 - 14**of**14**### The Spin of Holographic Electrons at Nonzero Density and Temperature

"... Abstract: We study the Green’s function of a gauge invariant fermionic operator in a strongly coupled field theory at nonzero temperature and density using a dual gravity de-scription. The gravity model contains a charged black hole in four dimensional anti-de Sitter space and probe charged fermions ..."

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Abstract: We study the Green’s function of a gauge invariant fermionic operator in a strongly coupled field theory at nonzero temperature and density using a dual gravity de-scription. The gravity model contains a charged black hole in four dimensional anti-de Sitter space and probe charged fermions. In particular, we consider the effects of the spin of these probe fermions on the properties of the Green’s function. There exists a spin-orbit coupling between the spin of an electron and the electric field of a Reissner-Nordström black hole. On the field theory side, this coupling leads to a Rashba like dispersion relation. We also study the effects of spin on the damping term in the dispersion relation by considering how the spin affects the placement of the fermionic quasinormal modes in the complex frequency plane in a WKB limit. An appendix contains some exact solutions of the Dirac equation in terms of Heun polynomials.

### arXiv: 1108.5577 RG flow of transport quantities

"... bhlATsogang.ac.kr, shesansuATgmail.com and sangjin.sinATgmail.com The RG flow equation of various transport quantities are studied in arbitrary spacetime dimensions, in the fixed as well as fluctuating background geometry both for the Maxwellian and DBI type of actions. The regularity condition on t ..."

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bhlATsogang.ac.kr, shesansuATgmail.com and sangjin.sinATgmail.com The RG flow equation of various transport quantities are studied in arbitrary spacetime dimensions, in the fixed as well as fluctuating background geometry both for the Maxwellian and DBI type of actions. The regularity condition on the flow equation of the conductivity at the horizon for the DBI action reproduces naturally the leading order result of Hartnoll et al., [JHEP, 04, 120 (2010)]. Motivated by the result of van der Marel et al., [science, 425, 271 (2003], we studied, analytically, the conductivity versus frequency plane by dividing it into three distinct parts: ω < T, ω> T and ω>> T. In order to compare, we choose 3 + 1 dimensional bulk spacetime for the computation of the conductivity. In the ω < T range, the conductivity does not show up the Drude like form in any spacetime dimensions. In the ω> T range and staying away from the horizon, for the DBI action with unit dynamical exponent, non-zero magnetic field and charge density, the conductivity goes as ω−2/3, whereas the phase of the conductivity, goes as, ArcTan(Imσxx/Reσxx) = pi/6 and ArcTan(Imσxy/Reσxy) = −pi/3. There exists a universal quantity at the horizon that is the phase angle of conductivity, which either vanishes or an integral multiple of pi. Furthermore, we calculate the temperature dependence to the thermoelectric and the thermal conductivity at the horizon. The charge diffusion constant for the DBI action is studied. ar X iv

### Imperial/TP/2011/JG/04 Spectral function of the supersymmetry current

"... We continue our study of the retarded Green’s function of the universal fermionic supersymmetry current (“supercurrent”) for the most general class of d = 3 N = 2 SCFTs with D = 10 or D = 11 supergravity du-als by studying the propagation of the Dirac gravitino in the electrically charged AdS-Reissn ..."

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We continue our study of the retarded Green’s function of the universal fermionic supersymmetry current (“supercurrent”) for the most general class of d = 3 N = 2 SCFTs with D = 10 or D = 11 supergravity du-als by studying the propagation of the Dirac gravitino in the electrically charged AdS-Reissner-Nordström black-brane background of N = 2 min-imal gauged supergravity in D = 4. We expand upon results presented in a companion paper, including the absence of a Fermi surface and the ap-pearance of a soft power-law gap at zero temperature. We also present the analytic solution of the gravitino equation in the AdS2 × R2 background which arises as the near-horizon limit at zero temperature. In addition we determine the quasinormal mode spectrum. ar X iv