Temperature Influence on the Properties of Thin Si3N4 Films

Applying Raman spectroscopy, small-angle x-ray scattering, and atomic force microscopy it were studied phase composition and surface morphology of nanoscale films Si3N4 (obtained by RF magnetron sputtering)

N=1 Supergravity Chaotic Inflation in the Braneworld Scenario

We study a N=1 Supergravity chaotic inflationary model, in the context of the braneworld scenario. It is shown that successful inflation and reheating consistent with phenomenological constraints can be achieved via the new terms in the Friedmann equation arising from brane physics. Interestingly, the model satisfies observational bounds with sub-Planckian field values, implying that chaotic inflation on the brane is free from the well known difficulties associated with the presence of higher order non-renormalizable terms in the superpotential. A bound on the mass scale of the fifth dimension, M_5 \gsim 1.3 \times 10^{-6} M_P, is obtained from the requirement that the reheating temperature be higher than the temperature of the electroweak phase transition.Comment: 5 pages, 1 Table, Revtex

Stationarity of Inflation and Predictions of Quantum Cosmology

We describe several different regimes which are possible in inflationary cosmology. The simplest one is inflation without self-reproduction of the universe. In this scenario the universe is not stationary. The second regime, which exists in a broad class of inflationary models, is eternal inflation with the self-reproduction of inflationary domains. In this regime local properties of domains with a given density and given values of fields do not depend on the time when these domains were produced. The probability distribution to find a domain with given properties in a self-reproducing universe may or may not be stationary, depending on the choice of an inflationary model. We give examples of models where each of these possibilities can be realized, and discuss some implications of our results for quantum cosmology. In particular, we propose a new mechanism which may help solving the cosmological constant problem.Comment: 30 pages, Stanford preprint SU-ITP-94-24, LaTe

From the Big Bang Theory to the Theory of a Stationary Universe

We consider chaotic inflation in the theories with the effective potentials phi^n and e^{\alpha\phi}. In such theories inflationary domains containing sufficiently large and homogeneous scalar field \phi permanently produce new inflationary domains of a similar type. We show that under certain conditions this process of the self-reproduction of the Universe can be described by a stationary distribution of probability, which means that the fraction of the physical volume of the Universe in a state with given properties (with given values of fields, with a given density of matter, etc.) does not depend on time, both at the stage of inflation and after it. This represents a strong deviation of inflationary cosmology from the standard Big Bang paradigm. We compare our approach with other approaches to quantum cosmology, and illustrate some of the general conclusions mentioned above with the results of a computer simulation of stochastic processes in the inflationary Universe.Comment: No changes to the file, but original figures are included. They substantially help to understand this paper, as well as eternal inflation in general, and what is now called the "multiverse" and the "string theory landscape." High quality figures can be found at http://www.stanford.edu/~alinde/LLMbigfigs

Relaxing the Cosmological Moduli Problem

Typically the moduli fields acquire mass m =C H in the early universe, which shifts the position of the minimum of their effective potential and leads to an excessively large energy density of the oscillating moduli fields at the later stages of the evolution of the universe. This constitutes the cosmological moduli problem, or Polonyi field problem. We show that the cosmological moduli problem can be solved or at least significantly relaxed in the theories in which C >> 1, as well as in some models with C << 1.Comment: 9 pages, 3 Postscript figure

Present status of the positive space charge lense for focusing intense negative charged particle beams

We describe the new experimental and simulation results of wide-aperture (6 cm) non-relativistic (up to 18 keV) intense (up to 400 mA) electron beam focusing by the positive-space-charge plasma lens. Recently we proposed and explored a new original plasma-optical tool for negative charged particle beams focusing and manipulating with a dynamic cloud of non-magnetized free positive ions and magnetically isolated electrons produced by a toroidal plasma source like an anode layer thruster. In such kind systems the electrons are separated from ions by relatively strong magnetic field in the discharge channel. The accelerated ions are weakly affected by the magnetic field owing to their mass. Focusing of the electron beam by electrostatic plasma lens was separated from magnetic focusing experimentally and the compression factor was up to about 5. The results of the computer simulation are shown good agreement with experimental data. Obtained experimental results demonstrate the possibility to create a lowcost high-effective tool for negatively-charged particle beam focusing without influence of momentum aberrations.Впервые наглядно продемонстрирован эффект фокусировки интенсивного широкоапертурного электронного пучка средних энергий электростатической плазменной линзой формирующей аксиально-симметричное облако положительного пространственного заряда в области прохождения пучка в условиях магнитной изоляции плазменных электронов линзы. Экспериментально измеренное фокусное расстояние плазменной линзы находится в согласии с расчетным значением. Достигнуто почти пятикратное увеличение плотности тока пучка на оси при совместном действии магнитного и электростатического полей линзы. Показана возможность четкой сепарации влияния магнитного и электрического полей на фокусировку проходящего электронного пучка.Вперше наочно продемонстровано ефект фокусування інтенсивного широкоапертурного електронного пучка середніх енергій електростатичною плазмовою лінзою, що формує аксіально-симетричну хмару позитивного просторового заряду в області проходження пучка в умовах магнітної ізоляції плазмових електронів лінзи. Експериментально виміряна фокусна відстань плазмової лінзи знаходиться у згоді з розрахунковим значенням. Досягнуто майже п’ятикратне збільшення густини струму пучка на осі при суміснїй дії магнітного та електростатичного полів лінзи. Показана спроможність виразної сепарації впливу магнітного і електричного полів на фокусування електронного пучка, що проходить

Islands in the landscape

The string theory landscape consists of many metastable de Sitter vacua, populated by eternal inflation. Tunneling between these vacua gives rise to a dynamical system, which asymptotically settles down to an equilibrium state. We investigate the effects of sinks to anti-de Sitter space, and show how their existence can change probabilities in the landscape. Sinks can disturb the thermal occupation numbers that would otherwise exist in the landscape and may cause regions that were previously in thermal contact to be divided into separate, thermally isolated islands.Comment: 31 pages, 8 figure

Topological Defects as Seeds for Eternal Inflation

We investigate the global structure of inflationary universe both by analytical methods and by computer simulations of stochastic processes in the early Universe. We show that the global structure of the universe depends crucially on the mechanism of inflation. In the simplest models of chaotic inflation the Universe looks like a sea of thermalized phase surrounding permanently self-reproducing inflationary domains. In the theories where inflation occurs near a local extremum of the effective potential corresponding to a metastable state, the Universe looks like de Sitter space surrounding islands of thermalized phase. A similar picture appears even if the state $\phi = 0$ is unstable but the effective potential has a discrete symmetry $\phi \to =-\phi$. In this case the Universe becomes divided into domains containing different phases. These domains will be separated from each other by domain walls. However, unlike ordinary domain walls, these domain walls will inflate, and their thickness will exponentially grow. In the theories with continuous symmetries inflation generates exponentially expanding strings and monopoles surrounded by thermalized phase. Inflating topological defects will be stable, and they will unceasingly produce new inflating topological defects. This means that topological defects may play a role of indestructible seeds for eternal inflation.Comment: 21 pages, 17 figures (not included), Stanford University preprint SU--ITP--94--

Temperature Influence on the Properties of Thin Si3N4 Films

Applying Raman spectroscopy, small-angle x-ray scattering, and atomic force microscopy it were studied phase composition and surface morphology of nanoscale films Si3N4 (obtained by RF magnetron sputtering)

Constraining the primordial spectrum of metric perturbations from gravitino and moduli production

We consider the production of gravitinos and moduli fields from quantum vacuum fluctuations induced by the presence of scalar metric perturbations at the end of inflation. We obtain the corresponding occupation numbers, up to first order in perturbation theory, in terms of the power spectrum of the metric perturbations. We compute the limits imposed by nucleosynthesis on the spectral index $n_s$ for different models with constant $n_s$. The results show that, in certain cases, such limits can be as strong as $n_s<1.12$, which is more stringent than those coming from primordial black hole production.Comment: 16 pages, LaTeX, 5 figures. Corrected figures, new references included. Final version to appear in Phys. Rev.