Static N=2 Black Holes For Quadratic Prepotentials

We employ the principle of minimal central charge and study the entropy of N=2 black holes corresponding to the most general quadratic prepotential. We also give a static black hole solution for these models in which the scalar moduli are non constants. Finally, we speculate on the microscopic origin for our solution.Comment: 8 pages, Latex fil

BPS black holes in N=2 five dimensional AdS supergravity

BPS black hole solutions of U(1) gauged five-dimensional supergravity are obtained by solving the Killing spinor equations. These extremal static black holes live in an asymptotic AdS_5 space time. Unlike black holes in asymptotic flat space time none of them possess a regular horizon. We also calculate the influence, of a particular class of these solutions, on the Wilson loops calculation.Comment: 8 pages, 1 figure, LaTeX, corrected the potentia

General Static N=2 Black Holes

We find general static BPS black hole solutions for general N=2, d=4 supergravity theories with an arbitrary number of vector multiplets. These solutions are completely specified by the K\"ahler potential of the underlying special K\"ahler geometry and a set of constrained harmonic functions.Comment: Latex, 7 pages, typos corrected, version to appear in MPL

Black Holes and Flop Transitions in M-Theory on Calabi-Yau Threefolds

We present fivedimensional extreme black hole solutions of M-theory compactified on Calabi-Yau threefolds and study these solutions in the context of flop transitions in the extended Kahler cone. In particular we consider a specific model and present black hole solutions, breaking half of N=2 supersymmetry, in two regions of the extended Kahler cone, which are connected by a flop transition. The conditions necessary to match both solutions at the flop transition are analysed. Finally we also discuss the conditions to obtain massless black holes at the flop transition.Comment: 19 pp, LaTe

Impact of sex and gender on COVID-19 outcomes in Europe

Emerging evidence from China suggests that coronavirus disease 2019 (COVID-19) is deadlier forinfected men than women with a 2.8% fatality rate being reported in Chinese men versus 1.7% in women. Further,sex-disaggregated data for COVID-19 in several European countries show a similar number of cases between thesexes, but more severe outcomes in aged men. Case fatality is highest in men with pre-existing cardiovascularconditions. The mechanisms accounting for the reduced case fatality rate in women are currently unclear but mayoffer potential to develop novel risk stratification tools and therapeutic options for women and men.Peer Reviewe

Black Holes in Supergravity and String Theory

We give an elementary introduction to black holes in supergravity and string theory. The focus is on BPS solutions in four- and higher-dimensional supergravity and string theory. Basic ideas and techniques are explained in detail, including exercises with solutions.Comment: 64 pages, based on lectures given at the school of the TMR network 'Quantum aspects of gauge theories, supersymmetry and unification' in Torino, January 26 - February 2, 2000. To be published in Class. Quant. Grav. (Some typos corrected, two references added.

Consistent reductions of IIB*/M* theory and de Sitter supergravity

We construct consistent non-linear Kaluza Klein reduction ansatze for a subset of fields arising from the reduction of IIB* and M* theory on dS_5 x H^5 and dS_4 x AdS_7, respectively. These reductions yield four and five-dimensional de Sitter supergravities, albeit with wrong sign kinetic terms. We also demonstrate that the ansatze may be used to lift multi-centered de Sitter black hole solutions to ten and eleven dimensions. The lifted dS_5 black holes correspond to rotating E4-branes of IIB* theory.Comment: 27 pages, late

HKT Geometry and Fake Five Dimensional Supergravity

Recent results on the relation between hyper-Kahler geometry with torsion and solutions admitting Killing spinors in minimal de sitter supergravity are extended to more general supergravity models with vector multiplets.Comment: 14 pages, latex. Minor typos corrected, references adde