Holographic Superconductors with the General RF2RF^2 type Couplings

We explore the effects of the general non-minimally coupled $RF^2$-type couplings on the holographic s-wave superconductors numerically in the Schwarzschild-AdS background. We calculate the condensation and conductivity of the model for the coupling parameters $a_1$ and $\beta$. We obtain that the bigger deviations of the parameter $a_1$ from the minimal case lead to the larger deviations of the gap frequency from the universal value $\omega_g/T_c \approx 8$. Moreover the smaller $\beta$ and $a_1$ cause to gradually stronger and narrower coherence peak.Comment: 12 pages, 14 figure

Regular Black Hole Solutions of the Non-minimally Coupled Y(R)F2Y(R)F^2 Gravity

In this study we investigate regular black hole solutions of the non-minimally coupled $Y(R)F^2$ gravity model. We give two regular black hole solutions and the corresponding non-minimal model for both electrically or magnetically charged cases. We calculate all the energy conditions for these solutions.Comment: 11 pages, some typos are correcte

Inflation of the Universe by the Non-minimal Y(R)F2Y(R)F^2 Models

The cosmological solutions of the non-minimal $Y (R)F^2$ theory which are compatible with FRW space-time are investigated. In order to avoid the isotropy violation of a vector field, it can be considered that the presence of a triplet of vector fields satisfying $SO(3)$ symmetry, or the average of randomly oriented electromagnetic fields over the sufficiently large volume. By considering the symmetry arguments, the inflation driven by the non-minimally coupled vector fields is studied. Then the cosmological solutions and corresponding models are obtained with the power law, hyperbolic and hybrid scale functions.Comment: 16 pages, accepted in MPL

Ioannis N. Grigoriadis, Instilling Religion in Greek and Turkish Nationalism: A”Sacred Synthesis”

Book Revie

Non-minimal RF2RF^2-type corrections to holographic superconductor

We study $(2+1)$-dimensional holographic superconductors in the presence of non-minimally coupled electromagnetic field to gravity by considering an arbitrary linear combination of $RF^2$-type invariants with three parameters. Our analytical analysis shows that the non-minimal couplings affect the condensate and the critical temperature.Comment: Accepted for publication in Modern Physics Letters

Spinor coupling to the weak Poincare gauge theory of gravity in three dimensions

Minimal coupling of a Dirac field to gravity with the most general non-propagating torsion is considered in (1+2)-dimensions. The field equations are obtained from a lagrangian by a variational principle. The space-time torsion is calculated algebraically in terms of a quadratic spinor condensate plus coupling coefficients. Firstly we give circularly symmetric rotating exact solutions that collapse to $AdS_3$ geometry in the absence of the Dirac condensate. Secondly we investigate a BTZ-like solution.Comment: We added a new subsection, corrected syntax errors, extended dicussion. To be published in Phys. Rev.