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Extremal black branes are of interest because they correspond to the ground states of field theories at finite charge density in gauge/gravity duality. The geometry of such a brane need not be translationally invariant in the spatial…

High Energy Physics - Theory · Physics 2015-06-03 Norihiro Iizuka , Shamit Kachru , Nilay Kundu , Prithvi Narayan , Nilanjan Sircar , Sandip P. Trivedi

In this letter we shall demonstrate that the viable $F(R)$ gravities can be classified mainly into two classes of inflationary attractors, either the $R^2$ attractors or the $\alpha$-attractors. To show this, we shall derive the most…

General Relativity and Quantum Cosmology · Physics 2020-08-26 S. D. Odintsov , V. K. Oikonomou

Transforming canonical scalars to the Einstein frame can give a multi-field generalization of pole inflation (namely, a scalar with a divergent kinetic term) at vanishing field-dependent Planck mass. However, to obtain an attractor, the…

High Energy Physics - Theory · Physics 2022-09-07 Sotirios Karamitsos , Alessandro Strumia

We systematically study the renormalizable three-term polynomial inflation in the supersymmetric and non-supersymmetric models. The supersymmetric inflaton potentials can be realized in supergravity theory, and only have two independent…

High Energy Physics - Phenomenology · Physics 2015-10-26 Tianjun Li , Zheng Sun , Chi Tian , Lina Wu

$\alpha$-attractor models naturally appear in supergravity with hyperbolic geometry. The simplest versions of $\alpha$-attractors, T- and E-models, originate from theories with non-singular potentials. In canonical variables, these…

High Energy Physics - Theory · Physics 2025-12-25 Renata Kallosh , Andrei Linde

Within the extremal black hole attractors arising in ungauged $\mathcal{N}\geqslant 2$-extended Maxwell Einstein supergravity theories in $3+1$ space-time dimensions, we provide an overview of the stratification of the electric-magnetic…

High Energy Physics - Theory · Physics 2023-12-21 Alessio Marrani

Here we analysed a particular type of $F(R)$ gravity, the so-called exponential gravity which includes an exponential function of the Ricci scalar in the action. Such term represents a correction to the usual Hilbert-Einstein action. By…

General Relativity and Quantum Cosmology · Physics 2018-01-17 Sergei D. Odintsov , Diego Saez-Chillon Gomez , German S. Sharov

Under consideration is the damped semilinear wave equation \[ u_{tt}+u_t-\Delta u+u+f(u)=0 \] in a bounded domain $\Omega$ in $\mathbb{R}^3$ subject to an acoustic boundary condition with a singular perturbation, which we term "massless…

Analysis of PDEs · Mathematics 2018-08-14 Joseph L. Shomberg

We construct a class of Einstein-vector theories where the vector field couples bilinearly to the curvature polynomials of arbitrary order in such a way that only Riemann tensor rather than its derivative enters the equations of motion. The…

High Energy Physics - Theory · Physics 2016-02-17 Wei-Jian Geng , H. Lu

In this work we study nonuniform exponential dichotomies and existence of pullback and forward attractors for evolution processes associated to nonautonomous differential equations. We define a new concept of nonuniform exponential…

Dynamical Systems · Mathematics 2021-12-14 Jose Antonio Langa , Rafael Obaya , Alexandre N. Oliveira-Sousa

We present a class of inflationary potentials which are invariant under a special symmetry, which depends on the parameters of the models. As we show, in certain limiting cases, the inverse symmetric potentials are qualitatively similar to…

General Relativity and Quantum Cosmology · Physics 2017-11-09 S. D. Odintsov , V. K. Oikonomou

We develop the attractors theory for the semigroups with multidimensional time belonging to some closed cone in an Euclidean space and apply the obtained general results to partial differential equations (PDEs) in unbounded domains. The…

Analysis of PDEs · Mathematics 2022-08-04 Anna Kostianko , Sergey Zelik

We introduce a family of $n$-dimensional Hamiltonian systems which, contain, as special reductions, several superintegrable systems as the Tremblay-Turbiner-Winternitz system, a generalized Kepler potential and the anisotropic harmonic…

Mathematical Physics · Physics 2022-12-21 Miguel A. Rodriguez , Piergiulio Tempesta

We present a number of new, exact scalar field cosmologies where the potential consists of two or more exponential terms. Such potentials are motivated by supergravity or superstring models formulated in higher dimensional spacetimes that…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Richard Easther

We disprove the Euclidean Einstein--Maxwell Black Hole Uniqueness Conjecture, and thus demonstrate that the semi-classical properties of coupled gravitational and electromagnetic fields are more subtle than expected from Lorentzian general…

General Relativity and Quantum Cosmology · Physics 2025-11-19 Bernardo Araneda , Maciej Dunajski

We study induced gravity dark energy models coupled with a simple monomial potential $\propto \sigma^n$ and a positive exponent $n$. These simple potentials lead to viable dark energy models with a weak dependence on the exponent, which…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-08 Mario Ballardini , Fabio Finelli , Caterina Umiltà , Daniela Paoletti

In the light of the new observational results we discuss the status of the exponential potentials driving inflation. We depart form the minimal scenario and study an inflaton kinetically coupled to the Einstein tensor. We find that in this…

High Energy Physics - Theory · Physics 2014-11-05 Iannis Dalianis , Fotis Farakos

We present $\alpha$-attractor models for inflation based on ${\cal N}=1$ supergravity with flat K\"ahler manifolds. The function form of the associated K\"ahler potential in these models are logarithmic square in nature and has a visible…

High Energy Physics - Theory · Physics 2018-12-19 Tony Pinhero

We investigate the symmetries of the near horizon geometry of extremal stationary black holes in four dimensional Einstein gravity coupled to abelian gauge fields and neutral scalars. Careful consideration of the equations of motion and the…

High Energy Physics - Theory · Physics 2008-11-26 Dumitru Astefanesei , Hossein Yavartanoo

We consider the Attractor Equations of particular $\mathcal{N}=2$, d=4 supergravity models whose vector multiplets' scalar manifold is endowed with homogeneous symmetric cubic special K\"{a}hler geometry, namely of the so-called $st^{2}$…

High Energy Physics - Theory · Physics 2008-11-26 S. Bellucci , A. Marrani , E. Orazi , A. Shcherbakov