Interaction between superconductors and weak gravitational field

We consider the interaction between the Earth's gravitational field and a superconductor in the fluctuation regime. Exploiting the weak field expansion formalism and using time dependent Ginzburg-Landau formulation, we show a possible short-time alteration of the gravitational field in the vicinity of the superconductor.Comment: 5 pages, 4 figure

Possible alterations of local gravitational field inside a superconductor

We calculate the possible interaction between a superconductor and the static Earth's gravitational fields, making use of the gravito-Maxwell formalism combined with the time-dependent Ginzburg-Landau theory. We try to estimate which are the most favourable conditions to enhance the effect, optimizing the superconductor parameters characterizing the chosen sample. We also give a qualitative comparison of the behaviour of high-$T_\text{c}$ and classical low-$T_\text{c}$ superconductors with respect to the gravity/superfluid interplay.Comment: 18 page

On D=4 Stationary Black Holes

We review some recent results concerning non-extremal and extremal stationary, asymptotically flat black hole solutions in extended D = 4 supergravities, and their properties with respect to the global symmetries of the theory. More specifically we refer to the effective three-dimensional description of these solutions and their classification within orbits with respect to the action of the global symmetry group, illustrating, for single-center solutions, the general mathematical relation between the orbits of non-extremal and extremal black holes

N\mathcal{N}-Extended D=4D=4 Supergravity, Unconventional SUSY and Graphene

We derive a $2+1$ dimensional model with unconventional supersymmetry at the boundary of an ${\rm AdS}_4$ $\mathcal{N}$-extended supergravity, generalizing previous results. The (unconventional) extended supersymmetry of the boundary model is instrumental in describing, within a top-down approach, the electronic properties of graphene-like 2D materials at the two Dirac points, ${\bf K}$ and ${\bf K}'$. The two valleys correspond to the two independent sectors of the ${\rm OSp}(p|2)\times {\rm OSp}(q|2)$ boundary model in the $p=q$ case, which are related by a parity transformation. The Semenoff and Haldane-type masses entering the corresponding Dirac equations are identified with the torsion parameters of the substrate in the model.Comment: 27 pages, 1 figur

Romans-mass-driven flows on the D2-brane

The addition of supersymmetric Chern-Simons terms to ${\cal N}=8$ super-Yang-Mills theory in three-dimensions is expected to make the latter flow into infrared superconformal phases. We address this problem holographically by studying the effect of the Romans mass on the D2-brane near-horizon geometry. Working in a consistent, effective four-dimensional setting provided by $D=4$ ${\cal N}=8$ supergravity with a dyonic $\textrm{ISO(7)}$ gauging, we verify the existence of a rich web of supersymmetric domain walls triggered by the Romans mass that interpolate between the (four-dimensional description of the) D2-brane and various superconformal phases. We also construct domain walls for which both endpoints are superconformal. While most of our results are numerical, we provide analytic results for the $\textrm{SU}(3)\times \textrm{U}(1)$-invariant flow into an ${\cal N}=2$ conformal phase recently discovered.Comment: 20 pages plus appendices, 5 figures. v2: typos corrected, published tex