Slow magnetic relaxation and hysteresis effects of dynamic origin have been observed above liquid helium temperature in a chain compound (see picture), comprising CoII centers organic radicals, without any evidence phase transition to three-dimensional order. These results are the first slow dynamics predicted for one-dimensional systems with Ising anisotropy, they open possibility storing information single nanowire.

We prove that the stochastic and standard field-theoretical approaches produce exactly same results for amount of light massive scalar field fluctuations generated during inflation in leading order slow-roll approximation. This is true both case which this a test one driven by another field, plays role inflaton itself. In latter case, to calculate mean square gauge-invariant fluctuations, logarithm scale factor $a$ has be used as time variable Fokker-Planck equation approach. The...

We compute the growth of mean square quantum fluctuations test fields with small effective mass during a slowly changing, nearly de Sitter stage which takes place in different inflationary models. consider minimally coupled scalar mass, modulus an $\ensuremath{\propto}{H}^{2}$ (with $H$ Hubble parameter), and massless nonminimally field approximation compare their relative one gauge-invariant inflaton fluctuations. find that most single models fluctuation grows faster than any non-negative...

We study a mechanism for the amplification of inflationary scalar perturbation when inflaton field action is non-canonical, i.e. kinetic term has non-standard form. For such case speed sound perturbations generated during inflation less than one and in general changes with time. Furthermore models, even potential negligible, diverse attractors may exist. The possible effects approaching zero some stage lead to large amplitude spectrum which, on horizon re-entry radiation dominated phase, can...

Informationsspeicherung in einzelnen magnetischen Nanodrähten? Die Grundlage hierfür könnten erste Hinweise auf die langsame Dynamik liefern, welche für eindimensionale magnetische Systeme mit Ising-Anisotropie vorhergesagt wurde: Langsame Relaxation und Hystereseeffekte dynamischen Ursprungs wurden oberhalb der Temperatur flüssigen Heliums einer Kettenverbindung beobachtet (siehe Bild), aus CoII-Zentren organischen Radikalen aufgebaut ist, ohne dass es einen Phasenübergang zu...

We consider a procedure of elimination cosmological singularities similar to that suggested in the recent paper by Simpson and Visser for construction regular black holes. It is shown imposing nonsingular evolution with bounce flat Friedmann universe filled minimally coupled scalar field, we obtain transition between standard field its phantom counterpart. In this case, potential has nonanalyticity cusp type. This result also readily reproduced case an anisotropic Bianchi I universe. have...

Some questions concerning the existence of time and validity Einstein's equations as a quantum-mechanical mean have arisen in development semiclassical gravity applied to cosmology. The first is technical question which concerns choice certain class solutions. We here show that this ``gauge'' where we follow work Mead Berry. ``Berry phase'' turns out be related integral energy. second concerned with justification use matter energy drive cosmological expansion. This shown valid an...

The cosmological consequences of a simple scalar field model for the generation Newton's constant through spontaneous breaking scale invariance in curved space are presented and discussed.Received 13 October 1981DOI:https://doi.org/10.1103/PhysRevD.24.3338©1981 American Physical Society

We obtain general solutions for some flat Friedmann universes filled with a scalar field in induced gravity models and including the Hilbert-Einstein curvature term plus conformally coupled to gravity. As is well known, these are connected minimally through combination of conformal transformation field. The explicit forms self-interaction potentials six exactly solvable presented here. solution one integrable models, namely, model power-law potential argue that although being mathematically...

We study the relation between Jordan-Einstein frame transition and possible description of crossing singularities in flat Friedmann universes, using fact that regular evolution one can correspond to other frame. show some interesting effects arise simple models such as with a massless scalar field or another wherein potential is constant Einstein The dynamics these their conformally coupled counterparts are described detail, method for continuation cosmological evolutions beyond singularity...

A global scale-invariant Dark Energy model based on Induced Gravity with the addition of a small $R^2$ contribution is examined. The scalar field (quintessence), playing role Energy, has quartic potential and generates Newton's constant its non-minimal coupling (after introducing suitable symmetry breaking). Even when small, significantly modifies cosmological evolution matter-gravity system. solutions to this are obtained analytically through perturbative expansion oscillate transplanckian...

The slow dynamics (10^-6 s - 10^4 s) of the magnetization in paramagnetic phase, predicted by Glauber for 1d Ising ferromagnets, has been observed with ac susceptibility and SQUID magnetometry measurements a molecular chain comprising alternating Co{2+} spins organic radical strongly antiferromagnetically coupled. An Arrhenius behavior activation energy Delta=152 K ten decades relaxation time found to be consistent model. We have extended this model take into account ferrimagnetic nature as...

In a series of recent papers Kallosh, Linde, and collaborators provide unified description single-field inflation with several types potentials ranging from power law to supergravity, in terms just one parameter $\ensuremath{\alpha}$. These so-called $\ensuremath{\alpha}$ attractors predict spectral index ${n}_{s}$ tensor-to-scalar ratio $r$, which are fully compatible the latest Planck data. The only common feature all is noncanonical kinetic term pole, potential analytic around pole. this...

We solve a general equation describing the lowest order corrections arising from quantum gravitational effects to spectrum of cosmological fluctuations. The spectra scalar and tensor perturbations are calculated first in slow roll approximation results compared with most recent observations. gives qualitatively new respect pure de Sitter case.

The Born - Oppenheimer approach to the matter gravity system is illustrated in a simple minisuperspace model and corrections quantum field theory on semiclassical background exhibited. Within such context unitary evolution for matter, absence of phenomena as tunnelling or other instabilities, verified compared with results approaches. Finally, simplifications associated use adiabatic invariants obtain solution explicitly time-dependent equation are given.

Inflation is studied in the context of induced gravity (IG) $\gamma \sigma^2 R$, where $R$ Ricci scalar, $\sigma$ a scalar field and $\gamma$ dimensionless constant. We study detail cosmological perturbations IG examine both Landau-Ginzburg (LG) Coleman-Weinberg (CW) potential toy models for small large (chaotic) inflation find that inflationary are constrained to \lesssim 3 \times 10^{-3}$ by WMAP 5 yrs data. Finally we describe regime coherent oscillations an analytic approximation,...

We employ the superpotential technique for reconstruction of cosmological models with a nonminimally coupled scalar field evolving on spatially flat Friedmann-Robertson-Walker background. The key point in this method is that Hubble parameter considered as function field, and allows one to reconstruct potential determine dynamics itself, without priori fixing time or scale factor. potentials lead de Sitter asymptotic solutions, those reproduce evolution given by Einstein-Hilbert action plus...

We study the cosmological evolution and singularity crossing in Bianchi-I universe filled with a conformally coupled scalar field compare them those of minimally field. also write down solution for Universe induced gravity cosmology.

We consider the relation between exact solutions of cosmological models having minimally and non-minimally coupled scalar fields. This is done for a particular class solvable which, in Einstein frame, have potentials depending on hyperbolic functions Jordan where non-minimal coupling conformal, possess relatively simple dynamics. show that model this can be generalized to cases closed open Friedmann universes still exhibits Further we illustrate conditions existences bounces some sub-classes...

We study static spherically and hyperbolically symmetric solutions of the Einstein equations in presence a conformally coupled scalar field compare them with those space filled minimally field. then Kantowski-Sachs cosmological solutions, which are connected by duality relations. The main ingredient these relations is an exchange roles between radial temporal coordinates, combined spherical hyperbolical two-dimensional geometries. A brief discussion questions such as relation Jordan frames...

We study the cosmological evolution of an induced gravity model with a self-interacting scalar field $σ$ and in presence matter radiation. Such leads to Einstein Gravity plus constant as stable attractor among homogeneous cosmologies is therefore viable dark-energy (DE) for wide range initial conditions values its positive $γ$ coupling Ricci curvature $γσ^{2}R$.

Improved Wentzel-Kramers-Brillouin (WKB)-type approximations are presented in order to study cosmological perturbations beyond the lowest order. Our methods based on functions which approximate true perturbation modes over complete range of independent (Langer) variable, from sub-horizon super-horizon scales, and include region near turning point. We employ both a perturbative Green's function technique an adiabatic (or ``semiclassical'') expansion (for linear point) compute higher...

We study the renormalized energy-momentum tensor (EMT) of cosmological scalar fluctuations during slow-rollover regime for chaotic inflation with a quadratic potential and find that it is characterized by negative energy density which grows slow rollover. also approach back-reaction problem as second-order calculation in perturbation theory, finding no evidence back reaction gauge artifact. In agreement results EMT, average expansion rate decreased fluctuations.