Search Results for « Higher derivative corrections »

Abstract We compute the most general leading-order correction to Kerr solution when the Einstein-Hilbert action is supplemented with higher-derivative terms, including the possibility of dynamical couplings controlled by scalars. The model we present depends on five parameters and it contains, as particular cases, Einstein-dilaton-Gauss-Bonnet gravity, dynamical Chern-Simons gravity and the effective action coming from Heterotic Superstring theory. By solving the corrected field equations, we find the modified Kerr metric that describes rotating black holes in these theories. We express the solution as a series in the spin parameter χ, and we show that including enough terms in the expansion we are able to describe black holes with large spin. For the computations in the text we use an expansion up to order χ 14, which is accurate for χ < 0.7, but we provide as well a Mathematica notebook that computes the solution at any given order. We study several properties of the corrected black holes, such as geometry of the horizon, ergosphere, light rings and scalar hair. Some of the corrections violate parity, and we highlight in those cases plots of horizons and ergospheres without ℤ2 symmetry.

Transport in strongly-disordered, metallic systems is governed by diffusive processes. Based on quantum mechanics, it has been conjectured that these diffusivities obey a lower bound D/v 2 ≳ ℏ/k B T , the saturation of which provides a mechanism for the T-linear resistivity of bad metals. This bound features a characteristic velocity v, which was later argued to be the butterfly velocity v B , based on holographic models of transport. This establishes a link between incoherent metallic transport, quantum chaos and Planckian timescales. Here we study higher derivative corrections to an effective holographic action of homogeneous disorder. The higher derivative terms involve only the charge and translation symmetry breaking sector. We show that they have a strong impact on the bound on charge diffusion D c /ν 2 ≳ ℏ/k B T, by potentially making the coefficient of its right-hand side arbitrarily small. On the other hand, the bound on energy diffusion is not affected.

Abstract In an effective field theory approach to gravity, the Einstein-Hilbert action is supplemented by higher derivative terms. In the absence of matter, four derivative terms can be eliminated by a field redefinition. We use the Euclidean action to calculate analytically the corrections to thermodynamic quantities of the Kerr solution arising from terms with six or eight derivatives. The eight derivative terms make a non-negative correction to the entropy (at fixed mass and angular momentum) if their coefficients have appropriate signs. The correction from the six derivative terms does not have a definite sign.

A bstract We quantitatively estimate the leading higher derivative corrections to $$ \mathcal{N} $$ N = 1 supergravity derived from IIB string compactifications and study how they may affect moduli stabilisation and LVS inflation models. Using the Kreuzer-Skarke database of 4D reflexive polytopes and their triangulated Calabi-Yau database, we present scanning results for a set of divisor topologies corresponding to threefolds with 1 ≤ h 1 , 1 ≤ 5. In particular, we find several geometries suitable to realise blow-up inflation, fibre inflation and poly-instantons inflation, together with a classification of the divisors topologies for which the leading higher derivative corrections to the inflationary potential vanish. In all other cases, we instead estimate numerically how these corrections modify the inflationary dynamics, finding that they do not destroy the predictions for the main cosmological observables.

We calculate in detail the disk level S-matrix element of one Ramond-Ramond field and three gauge field vertex operators in the world volume of BPS branes, to find four gauge field couplings to all orders of α ′ up to on-shell ambiguity. Then using these infinite couplings we find that the massless pole of the field theory amplitude is exactly equal to the massless pole S-matrix element of this amplitude for the p = n case to all orders of α ′. Finally we show that the infinite massless poles and the contact terms of this amplitude for the p = n + 2 case can be reproduced by the Born-Infeld action and the Wess-Zumino actions, and by their higher derivative corrections.

We consider the effect of the ${\mathcal{R}}^{4}$ term in type IIA string theory on the supergravity background dual to ${N}_{c}$ D4-branes compactified on a circle with supersymmetry breaking boundary conditions. We study the dynamics of D8-branes in this perturbed geometry in the probe approximation. This leads to an analysis of higher derivative corrections in holographic QCD beyond the supergravity approximation. We make a rough estimate of the corrections to the masses of some of the lightest (axial) vector mesons. The corrections are suppressed by a factor of $({g}_{\mathrm{YM}}^{2}{N}_{c}{)}^{\ensuremath{-}3}$ compared to their supergravity values. We find that the masses of these mesons increase from their supergravity values.