Cosmology as Science?: From Inflation to Eternity
CERN. Geneva
2009-01-01
The last decade or two have represented the golden age of observational cosmology, producing a revolution in our picture of the Universe on its largest scales, and perhaps also its smallest ones. I will argue that these recent development bring to the forefront some vexing questions about whether various fundamental assumptions about the universe are in fact falsifiable. I will focus on 3 issues: (1) "Proving" Inflation, (2) Dark Energy and Anthropic Arguments, and (3) Cosmology of the far future.Interview with Lawrence M. Krauss
Winitzki, Sergei
2009-01-01
This volume is the only monograph covering the exciting and dazzling recent developments in quantum cosmology, including the theory of the "multiverse" and eternal inflation pioneered by A Vilenkin, A Linde, S W Hawking, and others. Written by a leading expert in the field known for his depth and clarity of presentation, the volume presents an overview of 20 years of development of the theory of eternal inflation as well as a comprehensive, research-level introduction into the current methods and problems. This volume is invaluable for researchers as a definitive reference in the rapidly devel
International Nuclear Information System (INIS)
Barenboim, Gabriela; Park, Wan-Il; Kinney, William H.
2016-01-01
We consider eternal inflation in hilltop-type inflation models, favored by current data, in which the scalar field in inflation rolls off of a local maximum of the potential. Unlike chaotic or plateau-type inflation models, in hilltop inflation the region of field space which supports eternal inflation is finite, and the expansion rate H EI during eternal inflation is almost exactly the same as the expansion rate H * during slow roll inflation. Therefore, in any given Hubble volume, there is a finite and calculable expectation value for the lifetime of the ''eternal'' inflation phase, during which quantum flucutations dominate over classical field evolution. We show that despite this, inflation in hilltop models is nonetheless eternal in the sense that the volume of the spacetime at any finite time is exponentially dominated by regions which continue to inflate. This is true regardless of the energy scale of inflation, and eternal inflation is supported for inflation at arbitrarily low energy scale.
Inflation and quantum cosmology
International Nuclear Information System (INIS)
Linde, A.
1991-01-01
In this article a review of the present status of inflationary cosmology is given. We start with a discussion of the simplest version of the chaotic inflation scenario. Then we discuss some recent develoments in the inflationary cosmology, including the theory of a self-reproducing inflationary universe (eternal chaotic inflation). We do it with the help of stochastic approach to inflation. The results obtained within this approach are compared with the results obtained in the context of Euclidean quantum cosmology. (WL)
Directory of Open Access Journals (Sweden)
Koonin Eugene V
2007-05-01
Full Text Available Abstract Background Recent developments in cosmology radically change the conception of the universe as well as the very notions of "probable" and "possible". The model of eternal inflation implies that all macroscopic histories permitted by laws of physics are repeated an infinite number of times in the infinite multiverse. In contrast to the traditional cosmological models of a single, finite universe, this worldview provides for the origin of an infinite number of complex systems by chance, even as the probability of complexity emerging in any given region of the multiverse is extremely low. This change in perspective has profound implications for the history of any phenomenon, and life on earth cannot be an exception. Hypothesis Origin of life is a chicken and egg problem: for biological evolution that is governed, primarily, by natural selection, to take off, efficient systems for replication and translation are required, but even barebones cores of these systems appear to be products of extensive selection. The currently favored (partial solution is an RNA world without proteins in which replication is catalyzed by ribozymes and which serves as the cradle for the translation system. However, the RNA world faces its own hard problems as ribozyme-catalyzed RNA replication remains a hypothesis and the selective pressures behind the origin of translation remain mysterious. Eternal inflation offers a viable alternative that is untenable in a finite universe, i.e., that a coupled system of translation and replication emerged by chance, and became the breakthrough stage from which biological evolution, centered around Darwinian selection, took off. A corollary of this hypothesis is that an RNA world, as a diverse population of replicating RNA molecules, might have never existed. In this model, the stage for Darwinian selection is set by anthropic selection of complex systems that rarely but inevitably emerge by chance in the infinite universe
Koonin, Eugene V
2007-05-31
Recent developments in cosmology radically change the conception of the universe as well as the very notions of "probable" and "possible". The model of eternal inflation implies that all macroscopic histories permitted by laws of physics are repeated an infinite number of times in the infinite multiverse. In contrast to the traditional cosmological models of a single, finite universe, this worldview provides for the origin of an infinite number of complex systems by chance, even as the probability of complexity emerging in any given region of the multiverse is extremely low. This change in perspective has profound implications for the history of any phenomenon, and life on earth cannot be an exception. Origin of life is a chicken and egg problem: for biological evolution that is governed, primarily, by natural selection, to take off, efficient systems for replication and translation are required, but even barebones cores of these systems appear to be products of extensive selection. The currently favored (partial) solution is an RNA world without proteins in which replication is catalyzed by ribozymes and which serves as the cradle for the translation system. However, the RNA world faces its own hard problems as ribozyme-catalyzed RNA replication remains a hypothesis and the selective pressures behind the origin of translation remain mysterious. Eternal inflation offers a viable alternative that is untenable in a finite universe, i.e., that a coupled system of translation and replication emerged by chance, and became the breakthrough stage from which biological evolution, centered around Darwinian selection, took off. A corollary of this hypothesis is that an RNA world, as a diverse population of replicating RNA molecules, might have never existed. In this model, the stage for Darwinian selection is set by anthropic selection of complex systems that rarely but inevitably emerge by chance in the infinite universe (multiverse). The plausibility of different models
First observational tests of eternal inflation.
Feeney, Stephen M; Johnson, Matthew C; Mortlock, Daniel J; Peiris, Hiranya V
2011-08-12
The eternal inflation scenario predicts that our observable Universe resides inside a single bubble embedded in a vast inflating multiverse. We present the first observational tests of eternal inflation, performing a search for cosmological signatures of collisions with other bubble universes in cosmic microwave background data from the WMAP satellite. We conclude that the WMAP 7-year data do not warrant augmenting the cold dark matter model with a cosmological constant with bubble collisions, constraining the average number of detectable bubble collisions on the full sky N(s) < 1.6 at 68% C.L. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.
Mathematical issues in eternal inflation
Singh Kohli, Ikjyot; Haslam, Michael C.
2015-04-01
In this paper, we consider the problem of the existence and uniqueness of solutions to the Einstein field equations for a spatially flat Friedmann-Lemaître-Robertson-Walker universe in the context of stochastic eternal inflation, where the stochastic mechanism is modelled by adding a stochastic forcing term representing Gaussian white noise to the Klein-Gordon equation. We show that under these considerations, the Klein-Gordon equation actually becomes a stochastic differential equation. Therefore, the existence and uniqueness of solutions to Einstein’s equations depend on whether the coefficients of this stochastic differential equation obey Lipschitz continuity conditions. We show that for any choice of V(φ ), the Einstein field equations are not globally well-posed, hence, any solution found to these equations is not guaranteed to be unique. Instead, the coefficients are at best locally Lipschitz continuous in the physical state space of the dynamical variables, which only exist up to a finite explosion time. We further perform Feller’s explosion test for an arbitrary power-law inflaton potential and prove that all solutions to the Einstein field equations explode in a finite time with probability one. This implies that the mechanism of stochastic inflation thus considered cannot be described to be eternal, since the very concept of eternal inflation implies that the process continues indefinitely. We therefore argue that stochastic inflation based on a stochastic forcing term would not produce an infinite number of universes in some multiverse ensemble. In general, since the Einstein field equations in both situations are not well-posed, we further conclude that the existence of a multiverse via the stochastic eternal inflation mechanism considered in this paper is still very much an open question that will require much deeper investigation.
International Nuclear Information System (INIS)
Linde, A.D.
1986-05-01
It is shown that the universe evolution in the chaotic inflation scenario has no end and may have no beginning. According to this scenario, the universe consists of exponentially large number of different mini-universes inside which all possible metastable vacuum states and all possible types of compactification are realized. (author)
A smooth exit from eternal inflation?
Hawking, S. W.; Hertog, Thomas
2018-04-01
The usual theory of inflation breaks down in eternal inflation. We derive a dual description of eternal inflation in terms of a deformed Euclidean CFT located at the threshold of eternal inflation. The partition function gives the amplitude of different geometries of the threshold surface in the no-boundary state. Its local and global behavior in dual toy models shows that the amplitude is low for surfaces which are not nearly conformal to the round three-sphere and essentially zero for surfaces with negative curvature. Based on this we conjecture that the exit from eternal inflation does not produce an infinite fractal-like multiverse, but is finite and reasonably smooth.
(No) Eternal inflation and precision Higgs physics
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Arkani-Hamed, Nima; Dubovsky, Sergei; Senatore, Leonardo; Villadoro, Giovanni
2008-01-01
Even if nothing but a light Higgs is observed at the LHC, suggesting that the Standard Model is unmodified up to scales far above the weak scale, Higgs physics can yield surprises of fundamental significance for cosmology. As has long been known, the Standard Model vacuum may be metastable for low enough Higgs mass, but a specific value of the decay rate holds special significance: for a very narrow window of parameters, our Universe has not yet decayed but the current inflationary period can not be future eternal. Determining whether we are in this window requires exquisite but achievable experimental precision, with a measurement of the Higgs mass to 0.1 GeV at the LHC, the top mass to 60 MeV at a linear collider, as well as an improved determination of α s by an order of magnitude on the lattice. If the parameters are observed to lie in this special range, particle physics will establish that the future of our Universe is a global big crunch, without harboring pockets of eternal inflation, strongly suggesting that eternal inflation is censored by the fundamental theory. This conclusion could be drawn even more sharply if metastability with the appropriate decay rate is found in the MSSM, where the physics governing the instability can be directly probed at the TeV scale
Volume-weighted measure for eternal inflation
International Nuclear Information System (INIS)
Winitzki, Sergei
2008-01-01
I propose a new volume-weighted probability measure for cosmological 'multiverse' scenarios involving eternal inflation. The 'reheating-volume (RV) cutoff' calculates the distribution of observable quantities on a portion of the reheating hypersurface that is conditioned to be finite. The RV measure is gauge-invariant, does not suffer from the 'youngness paradox', and is independent of initial conditions at the beginning of inflation. In slow-roll inflationary models with a scalar inflaton, the RV-regulated probability distributions can be obtained by solving nonlinear diffusion equations. I discuss possible applications of the new measure to 'landscape' scenarios with bubble nucleation. As an illustration, I compute the predictions of the RV measure in a simple toy landscape.
Enqvist, K
2012-01-01
The very basics of cosmological inflation are discussed. We derive the equations of motion for the inflaton field, introduce the slow-roll parameters, and present the computation of the inflationary perturbations and their connection to the temperature fluctuations of the cosmic microwave background.
Is non-minimal inflation eternal?
International Nuclear Information System (INIS)
Feng, Chao-Jun; Li, Xin-Zhou
2010-01-01
The possibility that the non-minimal coupling inflation could be eternal is investigated. We calculate the quantum fluctuation of the inflaton in a Hubble time and find that it has the same value as that in the minimal case in the slow-roll limit. Armed with this result, we have studied some concrete non-minimal inflationary models including the chaotic inflation and the natural inflation, in which the inflaton is non-minimally coupled to the gravity. We find that the non-minimal coupling inflation could be eternal in some parameter spaces.
Global-local duality in eternal inflation
International Nuclear Information System (INIS)
Bousso, Raphael; Yang, I-S.
2009-01-01
We prove that the light-cone time cutoff on the multiverse defines the same probabilities as a causal patch with initial conditions in the longest-lived metastable vacuum. This establishes the equivalence of two measures of eternal inflation which naively appear very different (though both are motivated by holography). The duality can be traced to an underlying geometric relation which we identify.
Punctuated eternal inflation via AdS/CFT duality
International Nuclear Information System (INIS)
Lowe, David A.; Roy, Shubho
2010-01-01
The work is an attempt to model a scenario of inflation in the framework of anti-de Sitter/conformal field theory duality, a potentially complete nonperturbative description of quantum gravity. We study bubble geometries with de Sitter interiors within an ambient Schwarzschild anti-de Sitter black hole spacetime and the properties of the corresponding states in the dual conformal field theory. It is argued the viable bubble states can be identified with a subset of the black hole microstates. Consistency checks are performed and a number of implications regarding cosmology are discussed including how the key problems or paradoxes of conventional eternal inflation are overcome in this scenario.
Future foam: Nontrivial topology from bubble collisions in eternal inflation
International Nuclear Information System (INIS)
Bousso, Raphael; Freivogel, Ben; Yang, I-S.; Sekino, Yasuhiro; Shenker, Stephen; Susskind, Leonard; Yeh, C.-P.
2008-01-01
We study pocket universes which have zero cosmological constant and nontrivial boundary topology. These arise from bubble collisions in eternal inflation. Using a simplified dust model of collisions we find that boundaries of any genus can occur. Using a radiation shell model we perform analytic studies in the thin-wall limit to show the existence of geometries with a single toroidal boundary. We give plausibility arguments that higher genus boundaries can also occur. In geometries with one boundary of any genus a timelike observer can see the entire boundary. Geometries with multiple disconnected boundaries can also occur. In the spherical case with two boundaries the boundaries are separated by a horizon. Our results suggest that the holographic dual description for eternal inflation, proposed by Freivogel, Sekino, Susskind and Yeh, should include summation over the genus of the base space of the dual conformal field theory. We point out peculiarities of this genus expansion compared to the string perturbation series.
No-boundary measure in the regime of eternal inflation
International Nuclear Information System (INIS)
Hartle, James; Hawking, S. W.; Hertog, Thomas
2010-01-01
The no-boundary wave function (NBWF) specifies a measure for prediction in cosmology that selects inflationary histories and remains well behaved for spatially large or infinite universes. This paper explores the predictions of the NBWF for linear scalar fluctuations about homogeneous and isotropic backgrounds in models with a single scalar field moving in a quadratic potential. We treat both the spacetime geometry of the universe and the observers inhabiting it quantum mechanically. We evaluate top-down probabilities for local observations that are conditioned on the NBWF and on part of our data as observers of the universe. For models where the most probable histories do not have a regime of eternal inflation, the NBWF predicts homogeneity on large scales, a spectrum of observable fluctuations with a small non-Gaussian component, and a small amount of inflation in our past. By contrast, for models where the dominant histories have a regime of eternal inflation, the NBWF predicts significant inhomogeneity on scales much larger than the present horizon, a Gaussian spectrum of observable fluctuations, and a long period of inflation in our past. The absence or presence of non-Gaussianity in our observable universe therefore provides information about its global structure, assuming the NBWF.
Inflation and quantum cosmology
International Nuclear Information System (INIS)
Linde, A.
1990-01-01
We investigate an interplay between elementary particle physics, quantum cosmology and inflation. These results obtained within this approach are compared with the results obtained in the context of Euclidean quantum cosmology. In particular, we discuss relations between the stochastic approach to inflationary cosmology and the approaches based on the investigation of the Hartle-Hawking and tunneling wave functions of the universe. We argue that neither of these wave functions can be used for a complete description of the inflationary universe, but in certain cases they can be used for a description of some particular stages of inflation. It is shown that if the present vacuum energy density ρ υ exceeds some extremely small critical value ρ c (ρ c ∼ 10 -107 ) g cm -3 for chaotic inflation in the theory 1/2m 2 φ 2 ), then the lifetime of mankind in the inflationary universe should be finite, even though the universe as a whole will exist without end. A possible way to justify the anthropic principle in the context of the baby universe theory and to apply it to the evaluation of masses of elementary particles, of their coupling constants and of the vacuum energy density is also discussed. (author)
How decoherence affects the probability of slow-roll eternal inflation
Boddy, Kimberly K.; Carroll, Sean M.; Pollack, Jason
2017-07-01
Slow-roll inflation can become eternal if the quantum variance of the inflaton field around its slowly rolling classical trajectory is converted into a distribution of classical spacetimes inflating at different rates, and if the variance is large enough compared to the rate of classical rolling that the probability of an increased rate of expansion is sufficiently high. Both of these criteria depend sensitively on whether and how perturbation modes of the inflaton interact and decohere. Decoherence is inevitable as a result of gravitationally sourced interactions whose strength are proportional to the slow-roll parameters. However, the weakness of these interactions means that decoherence is typically delayed until several Hubble times after modes grow beyond the Hubble scale. We present perturbative evidence that decoherence of long-wavelength inflaton modes indeed leads to an ensemble of classical spacetimes with differing cosmological evolutions. We introduce the notion of per-branch observables—expectation values with respect to the different decohered branches of the wave function—and show that the evolution of modes on individual branches varies from branch to branch. Thus, single-field slow-roll inflation fulfills the quantum-mechanical criteria required for the validity of the standard picture of eternal inflation. For a given potential, the delayed decoherence can lead to slight quantitative adjustments to the regime in which the inflaton undergoes eternal inflation.
Inflation in the standard cosmological model
Uzan, Jean-Philippe
2015-12-01
The inflationary paradigm is now part of the standard cosmological model as a description of its primordial phase. While its original motivation was to solve the standard problems of the hot big bang model, it was soon understood that it offers a natural theory for the origin of the large-scale structure of the universe. Most models rely on a slow-rolling scalar field and enjoy very generic predictions. Besides, all the matter of the universe is produced by the decay of the inflaton field at the end of inflation during a phase of reheating. These predictions can be (and are) tested from their imprint of the large-scale structure and in particular the cosmic microwave background. Inflation stands as a window in physics where both general relativity and quantum field theory are at work and which can be observationally studied. It connects cosmology with high-energy physics. Today most models are constructed within extensions of the standard model, such as supersymmetry or string theory. Inflation also disrupts our vision of the universe, in particular with the ideas of chaotic inflation and eternal inflation that tend to promote the image of a very inhomogeneous universe with fractal structure on a large scale. This idea is also at the heart of further speculations, such as the multiverse. This introduction summarizes the connections between inflation and the hot big bang model and details the basics of its dynamics and predictions. xml:lang="fr"
Cosmology, inflation, and supersymmetry
International Nuclear Information System (INIS)
Albrecht, A.; Dimopoulos, S.; Fischler, W.; Kolb, E.W.; Raby, S.; Steinhardt, P.J.
1982-01-01
Cosmological consequences of supersymmetric grand unified models based on the Witten-O'Raifeartaigh potential are discussed. In particular we study the development of the phase transition in the spontaneous breaking of supersymmetry. We find that in realistic models where light fields feel supersymmetry breaking only through coupling to massive fields, e.g., the Geometric Hierarchy model, the universe does not inflate or reheat. Thus, the standard cosmological flatness, monopole, and horizon problems remain. In addition, we find that the transition is never completed, in the sense that the universe remains dominated by coherent Higgs field energy, resulting in an apparent matter dominated universe with Ω greater than or equal to 10 30
Eternal inflation and the quantum birth of cosmic structure
Energy Technology Data Exchange (ETDEWEB)
Leon, Gabriel [Universidad Nacional de La Plata, Grupo de Astrofisica, Relatividad y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina); Universidad de Buenos Aires, Ciudad Universitaria-Pab. I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)
2017-10-15
We consider the eternal inflation scenario of the slow-roll/chaotic type with the additional element of an objective collapse of the wave function. The incorporation of this new agent to the traditional inflationary setting might represent a possible solution to the quantum measurement problem during inflation, a subject that has not reached a consensus among the community. Specifically, it could provide an explanation for the generation of the primordial anisotropies and inhomogeneities, starting from a perfectly symmetric background and invoking symmetric dynamics. We adopt the continuous spontaneous localization model, in the context of inflation, as the dynamical reduction mechanism that generates the primordial inhomogeneities. Furthermore, when enforcing the objective reduction mechanism, the condition for eternal inflation can be bypassed. In particular, the collapse mechanism incites the wave function, corresponding to the inflaton, to localize itself around the zero mode of the field. Then the zero mode will evolve essentially unperturbed, driving inflation to an end in any region of the Universe where inflation occurred. Also, our approach achieves a primordial spectrum with an amplitude and shape consistent with the one that best fits the observational data. (orig.)
The phase transition to slow-roll eternal inflation
International Nuclear Information System (INIS)
Creminelli, P.; Dubovsky, S.; Nicolis, A.; Senatore, L.; Zaldarriaga, M.
2008-01-01
For slow-roll inflation we study the phase transition to the eternal regime. Starting from a finite inflationary volume, we consider the volume of the universe at reheating as order parameter. We show that there exists a critical value for the classical inflation speed, φ-dot 2 /H 4 = 3/(2 π 2 ), where the probability distribution for the reheating volume undergoes a sharp transition. In particular, for sub-critical inflation speeds all distribution moments become infinite. We show that at the same transition point the system develops a non-vanishing probability of having a strictly infinite reheating volume, while retaining a finite probability for finite values. Our analysis represents the exact quantum treatment of the system at lowest order in the slow-roll parameters and H 2 /M Pl 2 . (author)
Eternal inflation, bubble collisions, and the persistence of memory
International Nuclear Information System (INIS)
Garriga, Jaume; Guth, Alan H.; Vilenkin, Alexander
2007-01-01
A 'bubble universe' nucleating in an eternally inflating false vacuum will experience, in the course of its expansion, collisions with an infinite number of other bubbles. In an idealized model, we calculate the rate of collisions around an observer inside a given reference bubble. We show that the collision rate violates both the homogeneity and the isotropy of the bubble universe. Each bubble has a center which can be related to 'the beginning of inflation' in the parent false vacuum, and any observer not at the center will see an anisotropic bubble collision rate that peaks in the outward direction. Surprisingly, this memory of the onset of inflation persists no matter how much time elapses before the nucleation of the reference bubble
Eternal extended inflation and graceful exit from old inflation without Jordan-Brans-Dicke
Linde, Andrei
1990-10-01
Recently a possible solution to the graceful exit problem of the old inflation was proposed in the context of the Jordan-Brans-Dicke theory (extended inflation). In this paper we will argue that inflation in this theory occurs in a most natural way if it starts near the Planck density, as in the standard version of chaotic inflation. With most natural initial conditions, the inflationary universe in the JBD theory enters the stage of permanent reproduction of new inflationary domains (eternal extended inflation). In order to realize the extended inflation scenario at least two classical scalar fields driving inflation are necessary, as distinct from the simplest versions of new and chaotic inflation. It is shown that in the theory of two scalar fields one can solve the graceful exit problem even without modifying the Einstein gravity theory, due to the possibility that the decay rate of the false rate vacuum in old inflation depends on the value of the second scalar field and hence on time. Address after 1 September 1990: Physics Department, Stanford University, Varian Building, Stanford, CA 94305, USA.
Eternal extended inflation and graceful exit from old inflation without Jordan-Brans-Dicke
International Nuclear Information System (INIS)
Linde, A.
1990-01-01
Recently a possible solution to the graceful exit problem of the old inflation was proposed in the context of the Jordan-Brans-Dicke theory (extended inflation). In this paper we will argue that inflation in this theory occurs in a most natural way if it starts near the Planck density, as in the standard version of chaotic inflation. With most natural initial conditions, the inflationary universe in the JBD theory enters the stage of permanent reproduction of new inflationary domains (eternal extended inflation). In order to realize the extended inflation scenario at least two classical scalar fields driving inflation are necessary, as distinct from the simplest versions of new and chaotic inflation. It is shown that in the theory of two scalar fields one can solve the graceful exit problem even without modifying the Einstein gravity theory, due to the possibility that the decay rate of the false vacuum in old inflation depends on the value of the second scalar field and hence on time. (orig.)
Neutrino Masses in the Landscape and Global-Local Dualities in Eternal Inflation
Mainemer Katz, Dan
In this dissertation we study two topics in Theoretical Cosmology: one more formal, the other more phenomenological. We work in the context of eternally inflating cosmologies. These arise in any fundamental theory that contains at least one stable or metastable de Sitter vacuum. Each topic is presented in a different chapter: Chapter 1 deals with the measure problem in eternal inflation. Global-local duality is the equivalence of seemingly different regulators in eternal inflation. For example, the light- cone time cutoff (a global measure, which regulates time) makes the same predictions as the causal patch (a local measure that cuts off space). We show that global-local duality is far more general. It rests on a redundancy inherent in any global cutoff: at late times, an attractor regime is reached, characterized by the unlimited exponential self-reproduction of a certain fundamental region of spacetime. An equivalent local cutoff can be obtained by restricting to this fundamental region. We derive local duals to several global cutoffs of interest. The New Scale Factor Cutoff is dual to the Short Fat Geodesic, a geodesic of fixed infinitesimal proper width. Vilenkin's CAH Cutoff is equivalent to the Hubbletube, whose width is proportional to the local Hubble volume. The famous youngness problem of the Proper Time Cutoff can be readily understood by considering its local dual, the Incredible Shrinking Geodesic. The chapter closely follows our paper. Chapter 2 deals with the question of whether neutrino masses could be anthropically explained. The sum of active neutrino masses is well constrained, 58 meV ≤ mupsilon [is approximately less than] 0.23 eV, but the origin of this scale is not well understood. Here we investigate the possibility that it arises by environmental selection in a large landscape of vacua. Earlier work had noted the detrimental effects of neutrinos on large scale structure. However, using Boltzmann codes to compute the smoothed density
An introduction to cosmological inflation
International Nuclear Information System (INIS)
Liddle, A.R.
1999-01-01
An introductory account is given of the inflationary cosmology, which postulates a period of accelerated expansion during the Universe's earliest stages. The historical motivation is briefly outlined, and the modelling of the inflationary epoch explained. The most important aspect of inflation is that it provides a possible model for the origin of structure in the Universe, and key results are reviewed, along with a discussion of the current observational situation and outlook. (author)
Inflation and the theory of cosmological perturbations
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Riotto, A.
2003-01-01
These lectures provide a pedagogical introduction to inflation and the theory of cosmological perturbations generated during inflation which are thought to be the origin of structure in the universe. (author)
Inflation and cosmological parameter estimation
Energy Technology Data Exchange (ETDEWEB)
Hamann, J.
2007-05-15
In this work, we focus on two aspects of cosmological data analysis: inference of parameter values and the search for new effects in the inflationary sector. Constraints on cosmological parameters are commonly derived under the assumption of a minimal model. We point out that this procedure systematically underestimates errors and possibly biases estimates, due to overly restrictive assumptions. In a more conservative approach, we analyse cosmological data using a more general eleven-parameter model. We find that regions of the parameter space that were previously thought ruled out are still compatible with the data; the bounds on individual parameters are relaxed by up to a factor of two, compared to the results for the minimal six-parameter model. Moreover, we analyse a class of inflation models, in which the slow roll conditions are briefly violated, due to a step in the potential. We show that the presence of a step generically leads to an oscillating spectrum and perform a fit to CMB and galaxy clustering data. We do not find conclusive evidence for a step in the potential and derive strong bounds on quantities that parameterise the step. (orig.)
Cosmological perturbations in transient phantom inflation scenarios
Energy Technology Data Exchange (ETDEWEB)
Richarte, Martin G. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil); Universidad de Buenos Aires, Ciudad Universitaria 1428, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Kremer, Gilberto M. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil)
2017-01-15
We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that the present unified model only deals with a single field and that the transition between the two eras is achieved in a smooth way, so the model does not suffer from the eternal inflation issue. We explore the conditions for the crossing of the phantom divide line within the inflationary era along with the structural stability of several critical points. We study the behavior of the phantom field within the slow-climb approximation along with the necessary conditions to have sufficient inflation. We also examine the model at the level of classical perturbations within the Newtonian gauge and determine the behavior of the gravitational potential, contrast density and perturbed field near the inflation stage and the subsequent radiation era. (orig.)
Eternal inflation and a thermodynamic treatment of Einstein's equations
Energy Technology Data Exchange (ETDEWEB)
Ghersi, José Tomás Gálvez [Facultad de Ciencias, Universidad Nacional de Ingeniería, Lima, Perú (Peru); Geshnizjani, Ghazal; Shandera, Sarah [Perimeter Institute for Theoretical Physics, Waterloo, Ontario (Canada); Piazza, Federico, E-mail: jotogalgher@gmail.com, E-mail: ggeshnizjani@perimeterinstitute.ca, E-mail: fpiazza@apc.univ-paris7.fr, E-mail: sshandera@perimeterinstitute.ca [PCCP and APC, CNRS (UMR7164), Université Denis Diderot Paris 7, Batiment Condorcet, 10 rue Alice Domon et Léonie Duquet, 75205 Paris (France)
2011-06-01
In pursuing the intriguing resemblance of the Einstein equations to thermodynamic equations, most sharply seen in systems possessing horizons, we suggest that eternal inflation of the stochastic type may be a fruitful phenomenon to explore. We develop a thermodynamic first law for quasi-de Sitter space, valid on the horizon of a single observer's Hubble patch and explore consistancy with previous proposals for horizons of various types in dynamic and static situations. We use this framework to demonstrate that for the local observer fluctuations of the type necessary for stochastic eternal inflation fall within the regime where the thermodynamic approach is believed to apply. This scenario is interesting because of suggestive parallels with black hole evaporation.
Testing eternal inflation with the kinetic Sunyaev Zel'dovich effect
Energy Technology Data Exchange (ETDEWEB)
Zhang, Pengjie [Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, 955 Jianchuan road, Shanghai, 200240 (China); Johnson, Matthew C., E-mail: zhangpj@sjtu.edu.cn, E-mail: mjohnson@perimeterinstitute.ca [Department of Physics and Astronomy, York University, Toronto, On, M3J 1P3 (Canada)
2015-06-01
Perhaps the most controversial idea in modern cosmology is that our observable universe is contained within one bubble among many, all inhabiting the eternally inflating multiverse. One of the few way to test this idea is to look for evidence of the relic inhomogeneities left by the collisions between other bubbles and our own. Such relic inhomogeneities will induce a coherent bulk flow over Gpc scales. Therefore, bubble collisions leave unique imprints in the cosmic microwave background (CMB) through the kinetic Sunyaev Zel'dovich (kSZ) effect, temperature anisotropies induced by the scattering of photons from coherently moving free electrons in the diffuse intergalactic medium. The kSZ signature produced by bubble collisions has a unique directional dependence and is tightly correlated with the galaxy distribution; it can therefore be distinguished from other contributions to the CMB anisotropies. An important advantage of the kSZ signature is that it peaks on arcminute angular scales, where the limiting factors in making a detection are instrumental noise and foreground subtraction. This is in contrast to the collision signature in the primary CMB, which peaks on angular scales much larger than one degree, and whose detection is therefore limited by cosmic variance. In this paper, we examine the prospects for probing the inhomogeneities left by bubble collisions using the kSZ effect. We provide a forecast for detection using cross-correlations between CMB and galaxy surveys, finding that the detectability using the kSZ effect can be competitive with constraints from CMB temperature and polarization data.
Testing eternal inflation with the kinetic Sunyaev Zel'dovich effect
International Nuclear Information System (INIS)
Zhang, Pengjie; Johnson, Matthew C.
2015-01-01
Perhaps the most controversial idea in modern cosmology is that our observable universe is contained within one bubble among many, all inhabiting the eternally inflating multiverse. One of the few way to test this idea is to look for evidence of the relic inhomogeneities left by the collisions between other bubbles and our own. Such relic inhomogeneities will induce a coherent bulk flow over Gpc scales. Therefore, bubble collisions leave unique imprints in the cosmic microwave background (CMB) through the kinetic Sunyaev Zel'dovich (kSZ) effect, temperature anisotropies induced by the scattering of photons from coherently moving free electrons in the diffuse intergalactic medium. The kSZ signature produced by bubble collisions has a unique directional dependence and is tightly correlated with the galaxy distribution; it can therefore be distinguished from other contributions to the CMB anisotropies. An important advantage of the kSZ signature is that it peaks on arcminute angular scales, where the limiting factors in making a detection are instrumental noise and foreground subtraction. This is in contrast to the collision signature in the primary CMB, which peaks on angular scales much larger than one degree, and whose detection is therefore limited by cosmic variance. In this paper, we examine the prospects for probing the inhomogeneities left by bubble collisions using the kSZ effect. We provide a forecast for detection using cross-correlations between CMB and galaxy surveys, finding that the detectability using the kSZ effect can be competitive with constraints from CMB temperature and polarization data
Testing eternal inflation with the kinetic Sunyaev Zel'dovich effect
Zhang, Pengjie; Johnson, Matthew C.
2015-06-01
Perhaps the most controversial idea in modern cosmology is that our observable universe is contained within one bubble among many, all inhabiting the eternally inflating multiverse. One of the few way to test this idea is to look for evidence of the relic inhomogeneities left by the collisions between other bubbles and our own. Such relic inhomogeneities will induce a coherent bulk flow over Gpc scales. Therefore, bubble collisions leave unique imprints in the cosmic microwave background (CMB) through the kinetic Sunyaev Zel'dovich (kSZ) effect, temperature anisotropies induced by the scattering of photons from coherently moving free electrons in the diffuse intergalactic medium. The kSZ signature produced by bubble collisions has a unique directional dependence and is tightly correlated with the galaxy distribution; it can therefore be distinguished from other contributions to the CMB anisotropies. An important advantage of the kSZ signature is that it peaks on arcminute angular scales, where the limiting factors in making a detection are instrumental noise and foreground subtraction. This is in contrast to the collision signature in the primary CMB, which peaks on angular scales much larger than one degree, and whose detection is therefore limited by cosmic variance. In this paper, we examine the prospects for probing the inhomogeneities left by bubble collisions using the kSZ effect. We provide a forecast for detection using cross-correlations between CMB and galaxy surveys, finding that the detectability using the kSZ effect can be competitive with constraints from CMB temperature and polarization data.
Inflation after COBE: Lectures on inflationary cosmology
International Nuclear Information System (INIS)
Turner, M.S.
1992-01-01
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ''initial data'' for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models
Inflation after COBE: Lectures on inflationary cosmology
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. [Chicago Univ., IL (United States). Enrico Fermi Inst.]|[Fermi National Accelerator Lab., Batavia, IL (United States)
1992-12-31
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ``initial data`` for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models.
Universality of the Volume Bound in Slow-Roll Eternal Inflation
Energy Technology Data Exchange (ETDEWEB)
Dubovsky, Sergei; Senatore, Leonardo; Villadoro, Giovanni
2012-03-28
It has recently been shown that in single field slow-roll inflation the total volume cannot grow by a factor larger than e{sup S{sub dS}/2} without becoming infinite. The bound is saturated exactly at the phase transition to eternal inflation where the probability to produce infinite volume becomes non zero. We show that the bound holds sharply also in any space-time dimensions, when arbitrary higher-dimensional operators are included and in the multi-field inflationary case. The relation with the entropy of de Sitter and the universality of the bound strengthen the case for a deeper holographic interpretation. As a spin-off we provide the formalism to compute the probability distribution of the volume after inflation for generic multi-field models, which might help to address questions about the population of vacua of the landscape during slow-roll inflation.
Cosmological perturbations in the new Higgs inflation
Energy Technology Data Exchange (ETDEWEB)
Germani, Cristiano [Arnold Sommerfeld Center, Ludwig-Maximilians-University, Theresienstr, 37 80333 Muenchen (Germany); Kehagias, Alex, E-mail: cristiano.germani@lmu.de, E-mail: kehagias@central.ntua.gr [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece)
2010-05-01
We study the cosmological perturbations created during the New Higgs inflationary phase. In the New Higgs Inflation, the Higgs boson is kinetically coupled to the Einstein tensor and only three perturbative degrees of freedom, a scalar and two tensorial (gravitational waves), propagate during Inflation. Scalar perturbations are found to match the latest WMAP-7yrs data within Standard Model Higgs parameters. Primordial gravitational waves also, although propagating with superluminal speed, are consistent with present data. Finally, we estimate the values of the parameter of the New Higgs Inflation in relation to the Higgs mass, the spectral index and amplitude of the primordial scalar perturbations showing that the unitarity bound of the theory is not violated.
Higgs inflation and the cosmological constant
Energy Technology Data Exchange (ETDEWEB)
Jegerlehner, Fred [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2014-02-15
The Higgs not only induces the masses of all SM particles, the Higgs, given its special mass value, is the natural candidate for the inflaton and in fact is ruling the evolution of the early universe, by providing the necessary dark energy which remains the dominant energy density. SM running couplings not only allow us to extrapolate SM physics up to the Planck scale, but equally important they are triggering the Higgs mechanism. This is possible by the fact that the bare mass term in the Higgs potential changes sign at about μ{sub 0}≅1.40 x 10{sup 16} GeV and in the symmetric phase is enhanced by quadratic terms in the Planck mass. Such a huge Higgs mass term is able to play a key role in triggering inflation in the early universe. In this article we extend our previous investigation by working out the details of a Higgs inflation scenario. We show how different terms contributing to the Higgs Lagrangian are affecting inflation. Given the SM and its extrapolation to scales μ>μ{sub 0} we find a calculable cosmological constant V(0) which is weakly scale dependent and actually remains large during inflation. This is different to the Higgs fluctuation field dependent ΔV(φ), which decays exponentially during inflation, and actually would not provide a sufficient amount of inflation. The fluctuation field has a different effective mass which shifts the bare Higgs transition point to a lower value μ'{sub 0} ≅7.7 x 10{sup 14} GeV. The vacuum energy V(0) being proportional to M{sub Pl}{sup 4} has a coefficient which vanishes near the Higgs transition point, such that the bare and the renormalized cosmological constant match at this point. The role of the Higgs in reheating and baryogenesis is emphasized.
Cosmic time gauge in quantum cosmology and chaotic inflation model
International Nuclear Information System (INIS)
Hosoya, A.
1986-01-01
The author proposes a cosmic time gauge formalism in quantum cosmology to get an equation for the Schrodinger type. Its application to the chaotic inflation scenario reveals that the uncertainty in the scale factor grows exponentially as the universe inflates
Tunneling in cosmology and isothermal inflation
International Nuclear Information System (INIS)
Brout, R.; Spindel, P.
1991-01-01
The wave function for the universe, as proposed by Hartle and Hawking, experiences tunneling for small values of the radius of the universe. This induces thermal effects and so a hot big bang. We first give a detailed analysis of the observer accelerating in Minkowski space in terms of the tunneling of his wave function beyond his turning point. Applied to cosmology one finds a temperature at the big bang equal to the Gibbons-Hawking value. The residual thermal effects which result in an isothermal inflationary expansion give rise to a renormalized self-consistently determined Hubble constant (and hence Gibbons-Hawking temperature) through the trace anomaly. A thermodynamic interpretation is given. These results militate against phase transitions as a motor for inflation. (orig.)
Eternal inflation, bubble collisions, and the disintegration of the persistence of memory
International Nuclear Information System (INIS)
Freivogel, Ben; Kleban, Matthew; Nicolis, Alberto; Sigurdson, Kris
2009-01-01
We compute the probability distribution for bubble collisions in an inflating false vacuum which decays by bubble nucleation. Our analysis generalizes previous work of Guth, Garriga, and Vilenkin to the case of general cosmological evolution inside the bubble, and takes into account the dynamics of the domain walls that form between the colliding bubbles. We find that incorporating these effects changes the results dramatically: the total expected number of bubble collisions in the past lightcone of a typical observer is N ∼ γ V f /V i , where γ is the fastest decay rate of the false vacuum, V f is its vacuum energy, and V i is the vacuum energy during inflation inside the bubble. This number can be large in realistic models without tuning. In addition, we calculate the angular position and size distribution of the collisions on the cosmic microwave background sky, and demonstrate that the number of bubbles of observable angular size is N LS ∼ (Ω k ) 1/2 N, where Ω k is the curvature contribution to the total density at the time of observation. The distribution is almost exactly isotropic
Perturbative analysis of multiple-field cosmological inflation
International Nuclear Information System (INIS)
Lahiri, Joydev; Bhattacharya, Gautam
2006-01-01
We develop a general formalism for analyzing linear perturbations in multiple-field cosmological inflation based on the gauge-ready approach. Our inflationary model consists of an arbitrary number of scalar fields with non-minimal kinetic terms. We solve the equations for scalar- and tensor-type perturbations during inflation to the first order in slow roll, and then obtain the super-horizon solutions for adiabatic and isocurvature perturbations after inflation. Analytic expressions for power-spectra and spectral indices arising from multiple-field inflation are presented
Brane-world cosmology and inflation
Indian Academy of Sciences (India)
This brane-world scenario is quite attractive because of the non-trivial geometry in the bulk and because it successfully gives four-dimensional general relativity in the low energy limit. After reviewing basic features of the RS2 scenario, we consider a brane-world inflation model driven by the dynamics of a scalar field living ...
String cosmology. Large-field inflation in string theory
International Nuclear Information System (INIS)
Westphal, Alexander
2014-09-01
This is a short review of string cosmology. We wish to connect string-scale physics as closely as possible to observables accessible to current or near-future experiments. Our possible best hope to do so is a description of inflation in string theory. The energy scale of inflation can be as high as that of Grand Unification (GUT). If this is the case, this is the closest we can possibly get in energy scales to string-scale physics. Hence, GUT-scale inflation may be our best candidate phenomenon to preserve traces of string-scale dynamics. Our chance to look for such traces is the primordial gravitational wave, or tensor mode signal produced during inflation. For GUT-scale inflation this is strong enough to be potentially visible as a B-mode polarization of the cosmic microwave background (CMB). Moreover, a GUT-scale inflation model has a trans-Planckian excursion of the inflaton scalar field during the observable amount of inflation. Such large-field models of inflation have a clear need for symmetry protection against quantum corrections. This makes them ideal candidates for a description in a candidate fundamental theory like string theory. At the same time the need of large-field inflation models for UV completion makes them particularly susceptible to preserve imprints of their string-scale dynamics in the inflationary observables, the spectral index n s and the fractional tensor mode power r. Hence, we focus this review on axion monodromy inflation as a mechanism of large-field inflation in string theory.
Degravitation, inflation and the cosmological constant as an afterglow
International Nuclear Information System (INIS)
Patil, Subodh P.
2009-01-01
In this report, we adopt the phenomenological approach of taking the degravitation paradigm seriously as a consistent modification of gravity in the IR, and investigate its consequences for various cosmological situations. We motivate degravitation — where Netwon's constant is promoted to a scale dependent filter function — as arising from either a small (resonant) mass for the graviton, or as an effect in semi-classical gravity. After addressing how the Bianchi identities are to be satisfied in such a set up, we turn our attention towards the cosmological consequences of degravitation. By considering the example filter function corresponding to a resonantly massive graviton (with a filter scale larger than the present horizon scale), we show that slow roll inflation, hybrid inflation and old inflation remain quantitatively unchanged. We also find that the degravitation mechanism inherits a memory of past energy densities in the present epoch in such a way that is likely significant for present cosmological evolution. For example, if the universe underwent inflation in the past due to it having tunneled out of some false vacuum, we find that degravitation implies a remnant 'afterglow' cosmological constant, whose scale immediately afterwards is parametrically suppressed by the filter scale (L) in Planck units Λ ∼ l 2 pl /L 2 . We discuss circumstances through which this scenario reasonably yields the presently observed value for Λ ∼ O(10 −120 ). We also find that in a universe still currently trapped in some false vacuum state, resonance graviton models of degravitation only degravitate initially Planck or GUT scale energy densities down to the presently observed value over timescales comparable to the filter scale. We argue that different functional forms for the filter function will yield similar conclusions. In this way, we argue that although the degravitation models we study have the potential to explain why the cosmological constant is not large
Brane Inflation, Solitons and Cosmological Solutions: I
Energy Technology Data Exchange (ETDEWEB)
Chen, P.
2005-01-25
In this paper we study various cosmological solutions for a D3/D7 system directly from M-theory with fluxes and M2-branes. In M-theory, these solutions exist only if we incorporate higher derivative corrections from the curvatures as well as G-fluxes. We take these corrections into account and study a number of toy cosmologies, including one with a novel background for the D3/D7 system whose supergravity solution can be completely determined. Our new background preserves all the good properties of the original model and opens up avenues to investigate cosmological effects from wrapped branes and brane-antibrane annihilation, to name a few. We also discuss in some detail semilocal defects with higher global symmetries, for example exceptional ones, that occur in a slightly different regime of our D3/D7 model. We show that the D3/D7 system does have the required ingredients to realize these configurations as non-topological solitons of the theory. These constructions also allow us to give a physical meaning to the existence of certain underlying homogeneous quaternionic Kahler manifolds.
Measure problem in slow roll inflation and loop quantum cosmology
International Nuclear Information System (INIS)
Corichi, Alejandro; Karami, Asieh
2011-01-01
We consider the measure problem in standard slow-roll inflationary models from the perspective of loop quantum cosmology (LQC). Following recent results by Ashtekar and Sloan, we study the probability of having enough e-foldings and focus on its dependence on the quantum gravity scale, including the transition of the theory to the limit where general relativity (GR) is recovered. Contrary to the standard expectation, the probability of having enough inflation, that is close to 1 in LQC, grows and tends to 1 as one approaches the GR limit. We study the origin of the tension between these results with those by Gibbons and Turok, and offer an explanation that brings these apparent contradictory results into a coherent picture. As we show, the conflicting results stem from different choices of initial conditions for the computation of probability. The singularity-free scenario of loop quantum cosmology offers a natural choice of initial conditions, and suggests that enough inflation is generic.
Backreaction of Cosmological Fluctuations during Power-Law Inflation
International Nuclear Information System (INIS)
Marozzi, G.
2007-01-01
We study the renormalized energy-momentum tensor of cosmological scalar fluctuations during the slow-rollover regime for power-law inflation and find that it is characterized by a negative energy density at the leading order, with the same time behavior as the background energy. The average expansion rate appears decreased by the backreaction of the effective energy of cosmological fluctuations, but this value is comparable with the energy of the background only if inflation starts at a Planckian energy. We also find that, for this particular model, the first- and second-order inflaton fluctuations are decoupled and satisfy the same equation of motion. To conclude, the fourth-order adiabatic expansion for the inflaton scalar field is evaluated for a general potential V(φ)
Simple cosmological model with inflation and late times acceleration
Szydłowski, Marek; Stachowski, Aleksander
2018-03-01
In the framework of polynomial Palatini cosmology, we investigate a simple cosmological homogeneous and isotropic model with matter in the Einstein frame. We show that in this model during cosmic evolution, early inflation appears and the accelerating phase of the expansion for the late times. In this frame we obtain the Friedmann equation with matter and dark energy in the form of a scalar field with a potential whose form is determined in a covariant way by the Ricci scalar of the FRW metric. The energy density of matter and dark energy are also parameterized through the Ricci scalar. Early inflation is obtained only for an infinitesimally small fraction of energy density of matter. Between the matter and dark energy, there exists an interaction because the dark energy is decaying. For the characterization of inflation we calculate the slow roll parameters and the constant roll parameter in terms of the Ricci scalar. We have found a characteristic behavior of the time dependence of density of dark energy on the cosmic time following the logistic-like curve which interpolates two almost constant value phases. From the required numbers of N-folds we have found a bound on the model parameter.
Non-minimal Higgs inflation and frame dependence in cosmology
International Nuclear Information System (INIS)
Steinwachs, Christian F.; Kamenshchik, Alexander Yu.
2013-01-01
We investigate a very general class of cosmological models with scalar fields non-minimally coupled to gravity. A particular representative in this class is given by the non-minimal Higgs inflation model in which the Standard Model Higgs boson and the inflaton are described by one and the same scalar particle. While the predictions of the non-minimal Higgs inflation scenario come numerically remarkably close to the recently discovered mass of the Higgs boson, there remains a conceptual problem in this model that is associated with the choice of the cosmological frame. While the classical theory is independent of this choice, we find by an explicit calculation that already the first quantum corrections induce a frame dependence. We give a geometrical explanation of this frame dependence by embedding it into a more general field theoretical context. From this analysis, some conceptional points in the long lasting cosmological debate: 'Jordan frame vs. Einstein frame' become more transparent and in principle can be resolved in a natural way.
Non-minimal Higgs inflation and frame dependence in cosmology
Energy Technology Data Exchange (ETDEWEB)
Steinwachs, Christian F. [School of Mathematical Sciences, University of Nottingham University Park, Nottingham, NG7 2RD (United Kingdom); Kamenshchik, Alexander Yu. [Dipartimento di Fisica e Astronomia and INFN, Via Irnerio 46, 40126 Bologna, Italy and L.D. Landau Institute for Theoretical Physics of the Russian Academy of Sciences, Kosygin str. 2, 119334 Moscow (Russian Federation)
2013-02-21
We investigate a very general class of cosmological models with scalar fields non-minimally coupled to gravity. A particular representative in this class is given by the non-minimal Higgs inflation model in which the Standard Model Higgs boson and the inflaton are described by one and the same scalar particle. While the predictions of the non-minimal Higgs inflation scenario come numerically remarkably close to the recently discovered mass of the Higgs boson, there remains a conceptual problem in this model that is associated with the choice of the cosmological frame. While the classical theory is independent of this choice, we find by an explicit calculation that already the first quantum corrections induce a frame dependence. We give a geometrical explanation of this frame dependence by embedding it into a more general field theoretical context. From this analysis, some conceptional points in the long lasting cosmological debate: 'Jordan frame vs. Einstein frame' become more transparent and in principle can be resolved in a natural way.
The fissioning universe: Topological inflation and Kaluza-Klein cosmologies
International Nuclear Information System (INIS)
Kaku, Michio; Lykken, J.
1986-01-01
We propose a Kaluza-Klein cosmology by reversing the usual scenario: instead of starting with a flat 4+N dimensional universe in which N of the dimensions curl up into a compact manifold, we start with a compact 3+N dimensional manifold in which 3 of the dimensions are allowed to peel off and expand into the known universe. We reverse the usual ''spontaneous compactification'' scenario begin with a closed manifold Msup(3+N) which undergoes ''spontaneous fissioning'' into a product manifold M 3 xMsup(N). Remarkably, the 3-dimensional universe M 3 can undergo a rapid de Sitter expansion large enough to solve the horizon and flatness problem. We call this ''topological inflation'', which we propose as an alternative to the usual GUT inflation. The inflationary phase automatically terminates into a big bang phase. (orig.)
Cauchy horizon stability and mass inflation with a cosmological constant
International Nuclear Information System (INIS)
Costa, João L; Girão, Pedro M; Natário, José; Silva, Jorge Drumond
2015-01-01
Motivated by the strong cosmic censorship conjecture, we consider the Einstein- Maxwell-scalar field system with a cosmological constant Λ (of any sign), under spherical symmetry, for characteristic initial conditions, with outgoing data prescribed by a (complete) subextremal Reissner-Nordstrom black hole event horizon. We study the structure of the future maximal (globally hyperbolic) development, analyze the mass inflation scenarios, identifying, in particular, large choices of parameters for which the Hawking mass remains bounded, and study the existence of regular extensions. We also discuss why our results, although valid for all signs of Λ, only provide evidence for the failure of strong cosmic censorship in the case of a positive cosmological constant. (paper)
Exact solution in the cosmological chaotic inflation model with induced gravity
International Nuclear Information System (INIS)
Wang Wenfu
2004-01-01
We present a new, exact solution in the cosmological chaotic inflation model with induced gravity. The spectral index of the scalar density fluctuations, n s , is computed, and is consistent with the analyses of BOOMERANG data. The effective cosmological constant Λ eff tends to zero when inflation ends
Deflation of the cosmological constant associated with inflation and dark energy
International Nuclear Information System (INIS)
Geng, Chao-Qiang; Lee, Chung-Chi
2016-01-01
In order to solve the fine-tuning problem of the cosmological constant, we propose a simple model with the vacuum energy non-minimally coupled to the inflaton field. In this model, the vacuum energy decays to the inflaton during pre-inflation and inflation eras, so that the cosmological constant effectively deflates from the Planck mass scale to a much smaller one after inflation and plays the role of dark energy in the late-time of the universe. We show that our deflationary scenario is applicable to arbitrary slow-roll inflation models. We also take two specific inflation potentials to illustrate our results.
Starobinsky-Like Inflation in Dilaton-Brane Cosmology
Ellis, John; Nanopoulos, Dimitri V
2014-01-01
We discuss how Starobinsky-like inflation may emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane. The effective potential may acquire a constant term from a density of effectively point-like non-pertubative defects on the brane. Higher-genus corrections generate corrections to the effective potential that are exponentially damped at large field values, as in the Starobinsky model, but at a faster rate, leading to a smaller prediction for the tensor-to scalar perturbation ratio r. This may be compensated partially by logarithmic deformations on the world-sheet due to recoil of the defects due to scattering by string matter on the brane, which tend to enhance the tensor-to-scalar ratio.
Cosmology with torsion: An alternative to cosmic inflation
International Nuclear Information System (INIS)
Poplawski, Nikodem J.
2010-01-01
We propose a simple scenario which explains why our Universe appears spatially flat, homogeneous and isotropic. We use the Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity which naturally extends general relativity to include the spin of matter. The torsion of spacetime generates gravitational repulsion in the early Universe filled with quarks and leptons, preventing the cosmological singularity: the Universe expands from a state of minimum but finite radius. We show that the dynamics of the closed Universe immediately after this state naturally solves the flatness and horizon problems in cosmology because of an extremely small and negative torsion density parameter, Ω S ∼-10 -69 . Thus the ECKS gravity provides a compelling alternative to speculative mechanisms of standard cosmic inflation. This scenario also suggests that the contraction of our Universe preceding the bounce at the minimum radius may correspond to the dynamics of matter inside a collapsing black hole existing in another universe, which could explain the origin of the Big Bang.
Hybrid Inflation: Multi-field Dynamics and Cosmological Constraints
Clesse, Sébastien
2011-09-01
The dynamics of hybrid models is usually approximated by the evolution of a scalar field slowly rolling along a nearly flat valley. Inflation ends with a waterfall phase, due to a tachyonic instability. This final phase is usually assumed to be nearly instantaneous. In this thesis, we go beyond these approximations and analyze the exact 2-field dynamics of hybrid models. Several effects are put in evidence: 1) the possible slow-roll violations along the valley induce the non existence of inflation at small field values. Provided super-planckian fields, the scalar spectrum of the original model is red, in agreement with observations. 2) The initial field values are not fine-tuned along the valley but also occupy a considerable part of the field space exterior to it. They form a structure with fractal boundaries. Using bayesian methods, their distribution in the whole parameter space is studied. Natural bounds on the potential parameters are derived. 3) For the original model, inflation is found to continue for more than 60 e-folds along waterfall trajectories in some part of the parameter space. The scalar power spectrum of adiabatic perturbations is modified and is generically red, possibly in agreement with CMB observations. Topological defects are conveniently stretched outside the observable Universe. 4) The analysis of the initial conditions is extended to the case of a closed Universe, in which the initial singularity is replaced by a classical bounce. In the third part of the thesis, we study how the present CMB constraints on the cosmological parameters could be ameliorated with the observation of the 21cm cosmic background, by future giant radio-telescopes. Forecasts are determined for a characteristic Fast Fourier Transform Telescope, by using both Fisher matrix and MCMC methods.
Differentiating G-inflation from string gas cosmology using the effective field theory approach
Energy Technology Data Exchange (ETDEWEB)
He, Minxi; Liu, Junyu; Lu, Shiyun; Cai, Yi-Fu [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Zhou, Siyi; Wang, Yi [Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Brandenberger, Robert, E-mail: hmxz0@mail.ustc.edu.cn, E-mail: jliu2@caltech.edu, E-mail: shiyun@mail.ustc.edu.cn, E-mail: zhousiyi1@gmail.com, E-mail: yifucai@ustc.edu.cn, E-mail: phyw@ust.hk, E-mail: rhb@physics.mcgill.ca [Department of Physics, McGill University, Montréal, Quebec H3A 2T8 (Canada)
2016-12-01
A characteristic signature of String Gas Cosmology is primordial power spectra for scalar and tensor modes which are almost scale-invariant but with a red tilt for scalar modes but a blue tilt for tensor modes. This feature, however, can also be realized in the so-called G-inflation model, in which Horndeski operators are introduced which leads to a blue tensor tilt by softly breaking the Null Energy Condition. In this article we search for potential observational differences between these two cosmologies by performing detailed perturbation analyses based on the Effective Field Theory approach. Our results show that, although both two models produce blue tilted tensor perturbations, they behave differently in three aspects. Firstly, String Gas Cosmology predicts a specific consistency relation between the index of the scalar modes n {sub s} and that of tensor ones n {sub t} , which is hard to be reproduced by G-inflation. Secondly, String Gas Cosmology typically predicts non-Gaussianities which are highly suppressed on observable scales, while G-inflation gives rise to observationally large non-Gaussianities because the kinetic terms in the action become important during inflation. However, after finely tuning the model parameters of G-inflation it is possible to obtain a blue tensor spectrum and negligible non-Gaussianities with a degeneracy between the two models. This degeneracy can be broken by a third observable, namely the scale dependence of the nonlinearity parameter, which vanishes for G-inflation but has a blue tilt in the case of String Gas Cosmology. Therefore, we conclude that String Gas Cosmology is in principle observationally distinguishable from the single field inflationary cosmology, even allowing for modifications such as G-inflation.
International Nuclear Information System (INIS)
Contopoulos, G.; Kotsakis, D.
1987-01-01
An extensive first part on a wealth of observational results relevant to cosmology lays the foundation for the second and central part of the book; the chapters on general relativity, the various cosmological theories, and the early universe. The authors present in a complete and almost non-mathematical way the ideas and theoretical concepts of modern cosmology including the exciting impact of high-energy particle physics, e.g. in the concept of the ''inflationary universe''. The final part addresses the deeper implications of cosmology, the arrow of time, the universality of physical laws, inflation and causality, and the anthropic principle
Energy Technology Data Exchange (ETDEWEB)
Rajpoot, Subhash [California State University, Long Beach, CA (United States); Vacaru, Sergiu I. [Quantum Gravity Research, Topanga, CA (United States); University ' ' Al.I. Cuza' ' , Project IDEI, Iasi (Romania)
2017-05-15
Applying the anholonomic frame deformation method, we construct various classes of cosmological solutions for effective Einstein-Yang-Mills-Higgs, and two measure theories. The types of models considered are Freedman-Lemaitre-Robertson-Walker, Bianchi, Kasner and models with attractor configurations. The various regimes pertaining to plateau-type inflation, quadratic inflation, Starobinsky type and Higgs type inflation are presented. (orig.)
How robust are inflation model and dark matter constraints from cosmological data?
DEFF Research Database (Denmark)
Hamann, Jan; Hannestad, Steen; Sloth, Martin Snoager
2006-01-01
the tensor-to-scalar ratio r and the neutrino mass prevents lambda phi^4 from being excluded by present data. Reversing the argument, if lambda phi^4 is the correct model of inflation, it predicts a sum of neutrino masses at 0.3-0.5 eV, a range compatible with present experimental limits and within the reach......High-precision data from observation of the cosmic microwave background and the large scale structure of the universe provide very tight constraints on the effective parameters that describe cosmological inflation. Indeed, within a constrained class of LambdaCDM models, the simple lambda phi^4...... chaotic inflation model already appears to be ruled out by cosmological data. In this paper, we compute constraints on inflationary parameters within a more general framework that includes other physically motivated parameters such as a nonzero neutrino mass. We find that a strong degeneracy between...
García-Bellido, J
2015-01-01
In these lectures I review the present status of the so-called Standard Cosmological Model, based on the hot Big Bang Theory and the Inflationary Paradigm. I will make special emphasis on the recent developments in observational cosmology, mainly the acceleration of the universe, the precise measurements of the microwave background anisotropies, and the formation of structure like galaxies and clusters of galaxies from tiny primordial fluctuations generated during inflation.
Vacuum Energy and Inflation: 3. Newtonian Cosmology & GR
Huggins, Elisha
2013-01-01
This is paper #3 in a series of four papers on "vacuum energy" and inflation. In paper #1 [see EJ1024183] we discussed an example of what we have been calling vacuum energy. It is an energy with negative pressure whose energy density remains constant in an expanding space. We showed that an energy density with these properties exists…
Landscape predictions from cosmological vacuum selection
Energy Technology Data Exchange (ETDEWEB)
Bousso, Raphael; Bousso, Raphael; Yang, Sheng
2007-04-23
In Bousso-Polchinski models with hundreds of fluxes, we compute the effects of cosmological dynamics on the probability distribution of landscape vacua. Starting from generic initial conditions, we find that most fluxes are dynamically driven into a different and much narrower range of values than expected from landscape statistics alone. Hence, cosmological evolution will access only a tiny fraction of the vacua with small cosmological constant. This leads to a host of sharp predictions. Unlike other approaches to eternal inflation, the holographic measure employed here does not lead to staggering, an excessive spread of probabilities that would doom the string landscape as a solution to the cosmological constant problem.
Landscape predictions from cosmological vacuum selection
International Nuclear Information System (INIS)
Bousso, Raphael; Yang, I-S.
2007-01-01
In Bousso-Polchinski models with hundreds of fluxes, we compute the effects of cosmological dynamics on the probability distribution of landscape vacua. Starting from generic initial conditions, we find that most fluxes are dynamically driven into a different and much narrower range of values than expected from landscape statistics alone. Hence, cosmological evolution will access only a tiny fraction of the vacua with small cosmological constant. This leads to a host of sharp predictions. Unlike other approaches to eternal inflation, the holographic measure employed here does not lead to staggering, an excessive spread of probabilities that would doom the string landscape as a solution to the cosmological constant problem
Prospects of inflation in delicate D-brane cosmology
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Tsujikawa, Shinji
2007-01-01
We study D-brane inflation in a warped conifold background that includes brane-position dependent corrections for the nonperturbative superpotential. Instead of stabilizing the volume modulus χ at instantaneous minima of the potential and studying the inflation dynamics with an effective single field (radial distance between a brane and an antibrane) φ, we investigate the multifield inflation scenario involving these two fields. The two-field dynamics with the potential V(φ,χ) in this model is significantly different from the effective single-field description in terms of the field φ when the field χ is integrated out. The latter picture underestimates the total number of e-foldings even by 1 order of magnitude. We show that a correct single-field description is provided by a field ψ obtained from a rotation in the two-field space along the background trajectory. This model can give a large number of e-foldings required to solve flatness and horizon problems at the expense of fine-tunings of model parameters. We also estimate the spectra of density perturbations and show that the slow-roll parameter η ψψ =M pl 2 V ,ψψ /V in terms of the rotated field ψ determines the spectral index of scalar metric perturbations. We find that it is generally difficult to satisfy, simultaneously, both constraints of the spectral index and the cosmic background explorer normalization, while the tensor to scalar ratio is sufficiently small to match with observations
Cosmological constant, inflation and no-cloning theorem
Energy Technology Data Exchange (ETDEWEB)
Huang Qingguo, E-mail: huangqg@itp.ac.cn [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Science, Beijing 100190 (China); Lin Fengli, E-mail: linfengli@phy.ntnu.edu.tw [Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Department of Physics, National Taiwan Normal University, Taipei, 116, Taiwan (China)
2012-05-30
From the viewpoint of no-cloning theorem we postulate a relation between the current accelerated expansion of our universe and the inflationary expansion in the very early universe. It implies that the fate of our universe should be in a state with accelerated expansion. Quantitatively we find that the no-cloning theorem leads to a lower bound on the cosmological constant which is compatible with observations.
R2 cosmology: Inflation without a phase transition
International Nuclear Information System (INIS)
Mijic, M.B.; Morris, M.S.; Suen, W.
1986-01-01
A pure gravity inflationary model for the Universe is examined which is based on adding an εR 2 term to the usual gravitational Lagrangian. The classical evolution is worked out, including eventual particle production and the subsequent join to radiation-dominated Friedmann behavior. We show that this model gives significant inflation essentially independent of initial conditions. The model has only one free parameter which is bounded from above by observational constraints on scalar and tensorial perturbations and from below by both the need for standard baryogenesis and the need for galaxy formation. This requires 10/sup 11/<ε/sup -1/2/<10/sup 13/ GeV
Eternally existing self-reproducing inflationary universe
International Nuclear Information System (INIS)
Linde, A.D.
1986-05-01
It is shown that the large-scale quantum fluctuations of the scalar field φ generated in the chaotic inflation scenario lead to an infinite process of self-reproduction of inflationary mini-universes. A model of eternally existing chaotic inflationary universe is suggested. It is pointed out that whereas the universe locally is very homogeneous as a result of inflation, which occurs at the classical level, the global structure of the universe is determined by quantum effects and is highly non-trivial. The universe consists of exponentially large number of different mini-universes, inside which all possible (metastable) vacuum states and all possible types of compactification are realized. The picture differs crucially from the standard picture of a one-domain universe in a ''true'' vacuum state. Our results may serve as a justification of the anthropic principle in the inflationary cosmology. These results may have important implications for the elementary particle theory as well. Namely, since all possible types of mini-universes, in which inflation may occur, should exist in our universe, there is no need to insist (as it is usually done) that in realistic theories the vacuum state of our type should be the only possible one or the best one. (author)
International Nuclear Information System (INIS)
Gonzalez-Mestres, Luis
2016-01-01
A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of “anomalies”. Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang
Gonzalez-Mestres, Luis
2016-11-01
A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of "anomalies". Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang pattern
How robust are inflation model and dark matter constraints from cosmological data?
International Nuclear Information System (INIS)
Hamann, J.; Hannestad, S.; Sloth, M.S.; Wong, Y.Y.Y.
2006-11-01
High-precision data from observation of the cosmic microwave background and the large scale structure of the universe provide very tight constraints on the effective parameters that describe cosmological inflation. Indeed, within a constrained class of ΛCDM models, the simple λφ 4 chaotic inflation model already appears to be ruled out by cosmological data. In this paper, we compute constraints on inflationary parameters within a more general framework that includes other physically motivated parameters such as a nonzero neutrino mass. We find that a strong degeneracy between the tensor-to-scalar ratio τ and the neutrino mass prevents λφ 4 from being excluded by present data. Reversing the argument, if λφ 4 is the correct model of inflation, it predicts a sum of neutrino masses at 0.3→0.5 eV, a range compatible with present experimental limits and within the reach of the next generation of neutrino mass measurements. We also discuss the associated constraints on the dark matter density, the dark energy equation of state, and spatial curvature, and show that the allowed regions are significantly altered. Importantly, we find an allowed range of 0.094 c h 2 <0.136 for the dark matter density, a factor of two larger than that reported in previous studies. This expanded parameter space may have implications for constraints on SUSY dark matter models. (orig.)
Bubble nucleation in first-order inflation and other cosmological phase transitions
International Nuclear Information System (INIS)
Turner, M.S.; Weinberg, E.J.; Widrow, L.M.
1992-01-01
We address in some detail the kinematics of bubble nucleation and percolation in first-order cosmological phase transitions, with the primary focus on first-order inflation. We study how a first-order phase transition completes, describe measures of its progress, and compute the distribution of bubble sizes. For example, we find that the typical bubble size in a successful transition is of order 1% to 100% of the Hubble radius, and depends very weakly on the energy scale of the transition. We derive very general conditions that must be satisfied by Γ/H 4 to complete the phase transition (Γ=bubble nucleation rate per unit volume; H=expansion rate; physically, Γ/H 4 corresponds to the volume fraction of space occupied by bubbles nucleated over a Hubble time). In particular, Γ/H 4 must exceed 9/4π to successfully end inflation. To avoid the deleterious effects of bubbles nucleated early during inflation on primordial nucleosynthesis and on the isotropy and spectrum of the cosmic microwave background radiation, during most of inflation Γ/H 4 must be less than order 10 -4 --10 -3 . Our constraints imply that in a successful model of first-order inflation the phase transition must complete over a period of at most a few Hubble times and all but preclude individual bubbles from providing an interesting source of density perturbation. We note, though, that it is just possible for Poisson fluctuations in the number of moderately large-size bubbles to lead to interesting isocurvature perturbations, whose spectrum is not scale invariant. Finally, we analyze in detail several recently proposed models of first-order inflation
Cosmological attractor inflation from the RG-improved Higgs sector of finite gauge theory
Energy Technology Data Exchange (ETDEWEB)
Elizalde, Emilio; Odintsov, Sergei D. [Instituto de Ciencias del Espacio (ICE/CSIC) and Institut d' Estudis Espacials de Catalunya (IEEC), Campus UAB, Carrer de Can Magrans, s/n, Cerdanyola del Vallès, Barcelona, 08193 Spain (Spain); Pozdeeva, Ekaterina O.; Vernov, Sergey Yu., E-mail: elizalde@ieec.uab.es, E-mail: odintsov@ieec.uab.es, E-mail: pozdeeva@www-hep.sinp.msu.ru, E-mail: svernov@theory.sinp.msu.ru [Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119991 (Russian Federation)
2016-02-01
The possibility to construct an inflationary scenario for renormalization-group improved potentials corresponding to the Higgs sector of finite gauge models is investigated. Taking into account quantum corrections to the renormalization-group potential which sums all leading logs of perturbation theory is essential for a successful realization of the inflationary scenario, with very reasonable parameter values. The inflationary models thus obtained are seen to be in good agreement with the most recent and accurate observational data. More specifically, the values of the relevant inflationary parameters, n{sub s} and r, are close to the corresponding ones in the R{sup 2} and Higgs-driven inflation scenarios. It is shown that the model here constructed and Higgs-driven inflation belong to the same class of cosmological attractors.
Stable bounce and inflation in non-local higher derivative cosmology
International Nuclear Information System (INIS)
Biswas, Tirthabir; Koshelev, Alexey S.; Mazumdar, Anupam; Vernov, Sergey Yu.
2012-01-01
One of the greatest problems of primordial inflation is that the inflationary space-time is past-incomplete. This is mainly because Einstein's GR suffers from a space-like Big Bang singularity. It has recently been shown that ghost-free, non-local higher-derivative ultra-violet modifications of Einstein's gravity may be able to resolve the cosmological Big Bang singularity via a non-singular bounce. Within the framework of such non-local cosmological models, we are going to study both sub- and super-Hubble perturbations around an inflationary trajectory which is preceded by the Big Bounce in the past, and demonstrate that the inflationary trajectory has an ultra-violet completion and that perturbations do not suffer from any pathologies
Superhorizon curvaton amplitude in inflation and pre-big bang cosmology
DEFF Research Database (Denmark)
Sloth, Martin Snoager
2002-01-01
We follow the evolution of the curvaton on superhorizon scales and check that the spectral tilt of the curvaton perturbations is unchanged as the curvaton becomes non-relativistic. Both inflation and pre-big bang cosmology can be treated since the curvaton mechanism within the two scenarios works...... the same way. We also discuss the amplitude of the density perturbations, which leads to some interesting constrains on the pre-big bang scenario. It is shown that within a SL(3,R) non-linear sigma model one of the three axions has the right coupling to the dilaton and moduli to yield a flat spectrum...
Consistent cosmology with Higgs thermal inflation in a minimal extension of the MSSM
Energy Technology Data Exchange (ETDEWEB)
Hindmarsh, Mark [Dept. of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Jones, D.R. Timothy, E-mail: m.b.hindmarsh@sussex.ac.uk, E-mail: drtj@liv.ac.uk [Dept. of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX (United Kingdom)
2013-03-01
We consider a class of supersymmetric inflation models, in which minimal gauged F-term hybrid inflation is coupled renormalisably to the minimal supersymmetric standard model (MSSM), with no extra ingredients; we call this class the ''minimal hybrid inflationary supersymmetric standard model'' (MHISSM). The singlet inflaton couples to the Higgs as well as the waterfall fields, supplying the Higgs μ-term. We show how such models can exit inflation to a vacuum characterised by large Higgs vevs, whose vacuum energy is controlled by supersymmetry-breaking. The true ground state is reached after an intervening period of thermal inflation along the Higgs flat direction, which has important consequences for the cosmology of the F-term inflation scenario. The scalar spectral index is reduced, with a value of approximately 0.976 in the case where the inflaton potential is dominated by the 1-loop radiative corrections. The reheat temperature following thermal inflation is about 10{sup 9} GeV, which solves the gravitino overclosure problem. A Higgs condensate reduces the cosmic string mass per unit length, rendering it compatible with the Cosmic Microwave Background constraints without tuning the inflaton coupling. With the minimal U(1)' gauge symmetry in the inflation sector, where one of the waterfall fields generates a right-handed neutrino mass, we investigate the Higgs thermal inflation scenario in three popular supersymmetry-breaking schemes: AMSB, GMSB and the CMSSM, focusing on the implications for the gravitino bound. In AMSB enough gravitinos can be produced to account for the observed dark matter abundance through decays into neutralinos. In GMSB we find an upper bound on the gravitino mass of about a TeV, while in the CMSSM the thermally generated gravitinos are sub-dominant. When Big Bang Nucleosynthesis constraints are taken into account, the unstable gravitinos of AMSB and the CMSSM must have a mass O(10) TeV or greater, while in GMSB
Consistent cosmology with Higgs thermal inflation in a minimal extension of the MSSM
International Nuclear Information System (INIS)
Hindmarsh, Mark; Jones, D.R. Timothy
2013-01-01
We consider a class of supersymmetric inflation models, in which minimal gauged F-term hybrid inflation is coupled renormalisably to the minimal supersymmetric standard model (MSSM), with no extra ingredients; we call this class the ''minimal hybrid inflationary supersymmetric standard model'' (MHISSM). The singlet inflaton couples to the Higgs as well as the waterfall fields, supplying the Higgs μ-term. We show how such models can exit inflation to a vacuum characterised by large Higgs vevs, whose vacuum energy is controlled by supersymmetry-breaking. The true ground state is reached after an intervening period of thermal inflation along the Higgs flat direction, which has important consequences for the cosmology of the F-term inflation scenario. The scalar spectral index is reduced, with a value of approximately 0.976 in the case where the inflaton potential is dominated by the 1-loop radiative corrections. The reheat temperature following thermal inflation is about 10 9 GeV, which solves the gravitino overclosure problem. A Higgs condensate reduces the cosmic string mass per unit length, rendering it compatible with the Cosmic Microwave Background constraints without tuning the inflaton coupling. With the minimal U(1)' gauge symmetry in the inflation sector, where one of the waterfall fields generates a right-handed neutrino mass, we investigate the Higgs thermal inflation scenario in three popular supersymmetry-breaking schemes: AMSB, GMSB and the CMSSM, focusing on the implications for the gravitino bound. In AMSB enough gravitinos can be produced to account for the observed dark matter abundance through decays into neutralinos. In GMSB we find an upper bound on the gravitino mass of about a TeV, while in the CMSSM the thermally generated gravitinos are sub-dominant. When Big Bang Nucleosynthesis constraints are taken into account, the unstable gravitinos of AMSB and the CMSSM must have a mass O(10) TeV or greater, while in GMSB we find an upper bound on the
Consistent cosmology with Higgs thermal inflation in a minimal extension of the MSSM
Hindmarsh, Mark; Jones, D. R. Timothy
2013-03-01
We consider a class of supersymmetric inflation models, in which minimal gauged F-term hybrid inflation is coupled renormalisably to the minimal supersymmetric standard model (MSSM), with no extra ingredients; we call this class the ``minimal hybrid inflationary supersymmetric standard model'' (MHISSM). The singlet inflaton couples to the Higgs as well as the waterfall fields, supplying the Higgs μ-term. We show how such models can exit inflation to a vacuum characterised by large Higgs vevs, whose vacuum energy is controlled by supersymmetry-breaking. The true ground state is reached after an intervening period of thermal inflation along the Higgs flat direction, which has important consequences for the cosmology of the F-term inflation scenario. The scalar spectral index is reduced, with a value of approximately 0.976 in the case where the inflaton potential is dominated by the 1-loop radiative corrections. The reheat temperature following thermal inflation is about 109 GeV, which solves the gravitino overclosure problem. A Higgs condensate reduces the cosmic string mass per unit length, rendering it compatible with the Cosmic Microwave Background constraints without tuning the inflaton coupling. With the minimal U(1)' gauge symmetry in the inflation sector, where one of the waterfall fields generates a right-handed neutrino mass, we investigate the Higgs thermal inflation scenario in three popular supersymmetry-breaking schemes: AMSB, GMSB and the CMSSM, focusing on the implications for the gravitino bound. In AMSB enough gravitinos can be produced to account for the observed dark matter abundance through decays into neutralinos. In GMSB we find an upper bound on the gravitino mass of about a TeV, while in the CMSSM the thermally generated gravitinos are sub-dominant. When Big Bang Nucleosynthesis constraints are taken into account, the unstable gravitinos of AMSB and the CMSSM must have a mass O(10) TeV or greater, while in GMSB we find an upper bound on the
Unification of inflation, dark energy, and dark matter within the Salam-Sezgin cosmological model
International Nuclear Information System (INIS)
Henriques, Alfredo B.; Potting, Robertus; Sa, Paulo M.
2009-01-01
We investigate a cosmological model, based on the Salam-Sezgin six-dimensional supergravity theory and on previous work by Anchordoqui, Goldberg, Nawata, and Nunez. Assuming a period of warm inflation, we show that it is possible to extend the evolution of the model back in time, to include the inflationary period, thus unifying inflation, dark matter, and dark energy within a single framework. Like the previous authors, we were not able to obtain the full dark matter content of the universe from the Salam-Sezgin scalar fields. However, even if only partially successful, this work shows that present-day theories, based on superstrings and supergravity, may eventually lead to a comprehensive modeling of the evolution of the universe. We find that the gravitational-wave spectrum of the model has a nonconstant negative slope in the frequency range (10 -15 -10 6 ) rad/s, and that, unlike standard (cold) inflation models, it shows no structure in the MHz/GHz range of frequencies.
Inflation, the Higgs field and the resolution of the Cosmological Constant Paradox
De Martini, Francesco
2017-08-01
The nature of the scalar field responsible for the cosmological inflation, the ”inflaton”, is found to be rooted in the most fundamental concept of the Weyl’s differential geometry: the parallel displacement of vectors in curved space-time. Within this novel dynamical scenario, the standard electroweak theory of leptons based on the SU(2) L ⊗ U(1) Y as well as on the conformal groups of spacetime Weyl’s transformations is analyzed within the framework of a general-relativistic, co-covariant scalar-tensor theory that includes the electromagnetic and the Yang-Mills fields. A Higgs mechanism within a spontaneous symmetry breaking process is identified and this offers formal connections between some relevant properties of the elementary particles and the dark energy content of the Universe. An ”Effective Cosmological Potential”: Veff is expressed in terms of the dark energy potential: {V}{{Λ }}\\equiv {M}{{Λ }}2 via the ”mass reduction parameter”: \\zeta \\equiv \\sqrt{\\frac{|{V}eff|}{|{V}{{Λ }}|}}, a general property of the Universe. The mass of the Higgs boson, which is considered a ”free parameter” by the standard electroweak theory, by our theory is found to be proportional to the geometrical mean: {M}H\\propto \\sqrt{{M}eff× {M}P} of the Planck mass, MP and of the mass {M}eff\\equiv \\sqrt{|{V}eff|} which accounts for the measured Cosmological Constant, i.e. the measured content of vacuum-energy in the Universe. The experimental result obtained by the ATLAS and CMS Collaborations at CERN in the year 2012: MH = 125.09(GeV/c 2) leads by our theory to a value: Meff ~ 3.19 · 10-6(eV/c 2). The peculiar mathematical structure of Veff offers a clue towards the resolution of a most intriguing puzzle of modern quantum field theory, the ”Cosmological Constant Paradox”.
Reheating-volume measure for random-walk inflation
International Nuclear Information System (INIS)
Winitzki, Sergei
2008-01-01
The recently proposed 'reheating-volume' (RV) measure promises to solve the long-standing problem of extracting probabilistic predictions from cosmological multiverse scenarios involving eternal inflation. I give a detailed description of the new measure and its applications to generic models of eternal inflation of random-walk type. For those models I derive a general formula for RV-regulated probability distributions that is suitable for numerical computations. I show that the results of the RV cutoff in random-walk type models are always gauge invariant and independent of the initial conditions at the beginning of inflation. In a toy model where equal-time cutoffs lead to the 'youngness paradox', the RV cutoff yields unbiased results that are distinct from previously proposed measures.
Origin of inflation in CFT driven cosmology. R2-gravity and non-minimally coupled inflaton models
International Nuclear Information System (INIS)
Barvinsky, A.O.; Kamenshchik, A.Yu.; Nesterov, D.V.
2015-01-01
We present a detailed derivation of the recently suggested new type of hill-top inflation [arXiv:1509.07270] originating from the microcanonical density matrix initial conditions in cosmology driven by conformal field theory (CFT). The cosmological instantons of topology S 1 x S 3 , which set up these initial conditions, have the shape of a garland with multiple periodic oscillations of the scale factor of the spatial S 3 -section. They describe underbarrier oscillations of the inflaton and scale factor in the vicinity of the inflaton potential maximum, which gives a sufficient amount of inflation required by the known CMB data. We build the approximation of two coupled harmonic oscillators for these garland instantons and show that they can generate inflation consistent with the parameters of the CMB primordial power spectrum in the non-minimal Higgs inflation model and in R 2 gravity. In particular, the instanton solutions provide smallness of inflationary slow-roll parameters ε and η < 0 and their relation ε ∝ η 2 characteristic of these two models. We present the mechanism of formation of hill-like inflaton potentials, which is based on logarithmic loop corrections to the asymptotically shift-invariant tree-level potentials of these models in the Einstein frame. We also discuss the role of R 2 -gravity as an indispensable finite renormalization tool in the CFT driven cosmology, which guarantees the nondynamical (ghost free) nature of its scale factor and special properties of its cosmological garland-type instantons. Finally, as a solution to the problem of hierarchy between the Planckian scale and the inflation scale we discuss the concept of a hidden sector of conformal higher spin fields. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Barvinsky, A. O., E-mail: barvin@td.lpi.ru [Theory Department, Lebedev Physics Institute, Leninsky Prospect 53, 119991, Moscow (Russian Federation); Department of Physics, Tomsk State University, Lenin Ave. 36, 634050, Tomsk (Russian Federation); Department of Physics and Astronomy, Pacific Institute for Theoretical Physics, UBC, 6224 Agricultural Road, V6T1Z1, Vancouver, BC (Canada); Kamenshchik, A. Yu., E-mail: kamenshchik@bo.infn.it [Dipartimento di Fisica e Astronomia, Università di Bologna and INFN, Via Irnerio 46, 40126, Bologna (Italy); L. D. Landau Institute for Theoretical Physics, 119334, Moscow (Russian Federation); Nesterov, D. V., E-mail: nesterov@td.lpi.it [Theory Department, Lebedev Physics Institute, Leninsky Prospect 53, 119991, Moscow (Russian Federation)
2015-12-11
We present a detailed derivation of the recently suggested new type of hill-top inflation originating from the microcanonical density matrix initial conditions in cosmology driven by conformal field theory (CFT). The cosmological instantons of topology S{sup 1}×S{sup 3}, which set up these initial conditions, have the shape of a garland with multiple periodic oscillations of the scale factor of the spatial S{sup 3}-section. They describe underbarrier oscillations of the inflaton and scale factor in the vicinity of the inflaton potential maximum, which gives a sufficient amount of inflation required by the known CMB data. We build the approximation of two coupled harmonic oscillators for these garland instantons and show that they can generate inflation consistent with the parameters of the CMB primordial power spectrum in the non-minimal Higgs inflation model and in R{sup 2} gravity. In particular, the instanton solutions provide smallness of inflationary slow-roll parameters ϵ and η<0 and their relation ϵ∼η{sup 2} characteristic of these two models. We present the mechanism of formation of hill-like inflaton potentials, which is based on logarithmic loop corrections to the asymptotically shift-invariant tree-level potentials of these models in the Einstein frame. We also discuss the role of R{sup 2}-gravity as an indispensable finite renormalization tool in the CFT driven cosmology, which guarantees the non-dynamical (ghost free) nature of its scale factor and special properties of its cosmological garland-type instantons. Finally, as a solution to the problem of hierarchy between the Planckian scale and the inflation scale we discuss the concept of a hidden sector of conformal higher spin fields.
Particle physics and cosmology beyond the Standard Model: inflation, dark matter and flavour
International Nuclear Information System (INIS)
Heurtier, L.
2015-01-01
This thesis has been focusing on beyond the Standard Model aspects of particle physics and their implication in cosmology. We have gone through this work along the timeline of the Universe History focusing on three major topics that are the inflationary period, the dark matter relic density production and detection, and finally the question of flavor changing constraints on low energy supersymmetric theories. In the first part of this thesis, after reviewing the theoretical and phenomenological aspects of both the Big Bang theory and the theory of Inflation we will study in detail how describing Inflation in a high energy supersymmetric theory. The second part of this thesis is dedicated to dark matter. We have studied phenomenological aspects of simple models, extending the present Standard Model with simple abelian symmetries, by assuming that the constituent of dark matter would be able to exchange information with the visible sector by the help of a mediator particle. We have studied in particular possible interactions of heavy or light dark matter with respectively the strong and the electroweak sectors of the Standard Model. Our models are strongly constrained of course by experiments. The third part of this work will be dedicated to a different aspect of beyond Standard Model theories, that is the treatment of the flavour changing processes of particle physics. The Minimal Supersymmetric Standard Model (MSSM), as one of these possible enlargement of the Standard Model, introduces new processes of flavour changing that are highly constrained by experiment. We present some works in which we consider the possibility of adding so called Dirac Gauginos to the MSSM to render flavour changing weaker in the theory, and propose different flavour patterns theories
The influence of super-horizon scales on cosmological observables generated during inflation
Matarrese, Sabino; Musso, Marcello A.; Riotto, Antonio
2004-05-01
Using the techniques of out-of-equilibrium field theory, we study the influence on properties of cosmological perturbations generated during inflation on observable scales coming from fluctuations corresponding today to scales much bigger than the present Hubble radius. We write the effective action for the coarse grained inflaton perturbations, integrating out the sub-horizon modes, which manifest themselves as a coloured noise and lead to memory effects. Using the simple model of a scalar field with cubic self-interactions evolving in a fixed de Sitter background, we evaluate the two- and three-point correlation function on observable scales. Our basic procedure shows that perturbations do preserve some memory of the super-horizon scale dynamics, in the form of scale dependent imprints in the statistical moments. In particular, we find a blue tilt of the power spectrum on large scales, in agreement with the recent results of the WMAP collaboration which show a suppression of the lower multipoles in the cosmic microwave background anisotropies, and a substantial enhancement of the intrinsic non-Gaussianity on large scales.
International Nuclear Information System (INIS)
Ballesteros, Guillermo; Ringwald, Andreas; Tamarit, Carlos
2016-10-01
We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos N_i, a new color triplet Q and a complex SM-singlet scalar σ, whose vacuum expectation value υ_σ∝10"1"1 GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of σ and the SM Higgs and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model-Axion-Seesaw-Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.
Energy Technology Data Exchange (ETDEWEB)
Ballesteros, Guillermo [Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS, 91191 Gif-sur-Yvette (France); Redondo, Javier [Departamento de Física Teórica, Universidad de Zaragoza, Pedro Cerbuna 12, E-50009, Zaragoza (Spain); Ringwald, Andreas [DESY, Notkestr. 85, 22607 Hamburg (Germany); Tamarit, Carlos, E-mail: guillermo.ballesteros@cea.fr, E-mail: jredondo@unizar.es, E-mail: andreas.ringwald@desy.de, E-mail: carlos.tamarit@durham.ac.uk [Institute for Particle Physics Phenomenology, Durham University, South Road, DH1 3LE (United Kingdom)
2017-08-01
We present a minimal extension of the Standard Model (SM) providing a consistent picture of particle physics from the electroweak scale to the Planck scale and of cosmology from inflation until today. Three right-handed neutrinos N {sub i} , a new color triplet Q and a complex SM-singlet scalar σ, whose vacuum expectation value v {sub σ} ∼ 10{sup 11} GeV breaks lepton number and a Peccei-Quinn symmetry simultaneously, are added to the SM. At low energies, the model reduces to the SM, augmented by seesaw generated neutrino masses and mixing, plus the axion. The latter solves the strong CP problem and accounts for the cold dark matter in the Universe. The inflaton is comprised by a mixture of σ and the SM Higgs, and reheating of the Universe after inflation proceeds via the Higgs portal. Baryogenesis occurs via thermal leptogenesis. Thus, five fundamental problems of particle physics and cosmology are solved at one stroke in this unified Standard Model—axion—seesaw—Higgs portal inflation (SMASH) model. It can be probed decisively by upcoming cosmic microwave background and axion dark matter experiments.
International Nuclear Information System (INIS)
Novikov, I.D.
1979-01-01
Progress made by this Commission over the period 1976-1978 is reviewed. Topics include the Hubble constant, deceleration parameter, large-scale distribution of matter in the universe, radio astronomy and cosmology, space astronomy and cosmology, formation of galaxies, physics near the cosmological singularity, and unconventional cosmological models. (C.F.)
Cosmological constant in the quantum multiverse
International Nuclear Information System (INIS)
Larsen, Grant; Nomura, Yasunori; Roberts, Hannes L. L.
2011-01-01
Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. In this paper, we elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein.
Inflationary cosmologies from compactification?
International Nuclear Information System (INIS)
Wohlfarth, Mattias N.R.
2004-01-01
We consider the compactification of (d+n)-dimensional pure gravity and of superstring or M-theory on an n-dimensional internal space to a d-dimensional Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology, with a spatial curvature k=0,±1, in the Einstein conformal frame. The internal space is taken to be a product of Einstein spaces, each of which is allowed to have arbitrary curvature and a time-dependent volume. By investigating the effective d-dimensional scalar potential, which is a sum of exponentials, it is shown that such compactifications, in the k=0,+1 cases, do not lead to large amounts of accelerating expansion of the scale factor of the resulting FLRW universe, and, in particular, do not lead to inflation. The case k=-1 admits solutions with eternal accelerating expansion for which the acceleration, however, tends to zero at late times
International Nuclear Information System (INIS)
Gato, B.; Leon, J.; Ramon-Medrano, M.
1984-01-01
We present a model for a SUSY GUT coupled to N=1 supergravity in which local supersymmetry breaks down in the gauge singlet sector. The constraints for the model to be physically acceptable are incompatible with inflation. The simultaneous breaking of local supersymmetry and gauge symmetry is proposed as a good prospect for inflation. (orig.)
Entropy generation and inflation in collision induced pre-big-bang cosmology
Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.
2000-01-01
We study inflation and entropy generation in a recently proposed pre-big-bang model universe produced in a collision of gravitational and dilaton waves. It is shown that enough inflation occurs provided the incoming waves are sufficiently weak. We also find that entropy in this model is dynamically
Quintessential inflation from a variable cosmological constant in a 5D vacuum
Membiela, Agustin; Bellini, Mauricio
2006-01-01
We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experiental data that the coupling of the inflaton with gravity should be...
International Nuclear Information System (INIS)
Nielsen, Holger B.; Ninomiya, Masao
2006-01-01
We seek to unify the second law of thermodynamics with other physical laws, or, at least to find a law underlying the second law of thermodynamics. Assuming no fine tuning, using a random Hamiltonian, we argue just from the equations of motion - without the second law - that entropy cannot first increase and then decrease except with the rather strict restriction S large ≤ S small1 + S small2 . Here S large is the large' entropy in the intermediate era, while S small1 and S small2 are the entropies at certain times before and after the S large era. From this theorem asserting that there can exist no strong maximum for the entropy, we argue that an S 1 cyclic time model world could have entropy that varies by at most a factor of two and would not be phenomenologically realistic. With an open ended time axis (-∞, ∞)=R, some law underlying the second law of thermodynamics is needed if the entropy is not maximal (i.e. that heat death having y occurred at the start). We derive such a law behind the second law - or a unification of the second law with other laws - by assigning a probability weight P for finding the world/system in various places in phase space. In such a model, P is almost unified with the rest as P=exp(-2S Im ), with S Im being the imaginary part of the action. We quite naturally derive the second law for practical purposes, a Big Bang with two-sided time directions, and find that there is a need for a Hamiltonian density with a well-defined bottom. Assuming that the cosmological constant is a dynamical variable in the sense that it is counted as on 'initial condition', we even solve in our model the cosmological constant problem without using the anthropic principle. (author)
Inflation and late-time acceleration in braneworld cosmological models with varying brane tension
International Nuclear Information System (INIS)
Wong, K.C.; Cheng, K.S.; Harko, T.
2010-01-01
Braneworld models with variable brane tension λ introduce a new degree of freedom that allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We consider a thermodynamic interpretation of the varying brane tension models, by showing that the field equations with variable λ can be interpreted as describing matter creation in a cosmological framework. The particle creation rate is determined by the variation rate of the brane tension, as well as by the brane-bulk energy-matter transfer rate. We investigate the effect of a variable brane tension on the cosmological evolution of the Universe, in the framework of a particular model in which the brane tension is an exponentially dependent function of the scale factor. The resulting cosmology shows the presence of an initial inflationary expansion, followed by a decelerating phase, and by a smooth transition towards a late accelerated de Sitter type expansion. The varying brane tension is also responsible for the generation of the matter in the Universe (reheating period). The physical constraints on the model parameters, resulting from the observational cosmological data, are also investigated. (orig.)
Particle physics and inflationary cosmology
Linde, Andrei D
1990-01-01
This is the LaTeX version of my book "Particle Physics and Inflationary Cosmology'' (Harwood, Chur, Switzerland, 1990). I decided to put it to hep-th, to make it easily available. Many things happened during the 15 years since the time when it was written. In particular, we have learned a lot about the high temperature behavior in the electroweak theory and about baryogenesis. A discovery of the acceleration of the universe has changed the way we are thinking about the problem of the vacuum energy: Instead of trying to explain why it is zero, we are trying to understand why it is anomalously small. Recent cosmological observations have shown that the universe is flat, or almost exactly flat, and confirmed many other predictions of inflationary theory. Many new versions of this theory have been developed, including hybrid inflation and inflationary models based on string theory. There was a substantial progress in the theory of reheating of the universe after inflation, and in the theory of eternal inflation. ...
Quintessential inflation from a variable cosmological constant in a 5D vacuum
Membiela, Agustin; Bellini, Mauricio
2006-10-01
We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experimental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe.
Quintessential inflation from a variable cosmological constant in a 5D vacuum
Energy Technology Data Exchange (ETDEWEB)
Membiela, Agustin [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata (Argentina)]. E-mail: membiela@argentina.com; Bellini, Mauricio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata (Argentina) and Consejo Nacional de Ciencia y Tecnologia (CONICET) (Argentina)]. E-mail: mbellini@mdp.edu.ar
2006-10-05
We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experimental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe.
Quintessential inflation from a variable cosmological constant in a 5D vacuum
International Nuclear Information System (INIS)
Membiela, Agustin; Bellini, Mauricio
2006-01-01
We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experimental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe
Cosmological Inflation with Multiple Fields and the Theory of Density Fluctuations
Tent, B.J.W. van
2002-01-01
Inflation is a stage of extremely rapid expansion in the very early universe. It was proposed to solve a number of problems in the standard Big Bang theory. In particular it others an explanation for the origin of structures like (clusters of) galaxies on the one hand (by generating small density
CERN. Geneva
2014-01-01
We discuss a corpuscular resolution of inflation. In our treatment, the geometric background is viewed as a composite entity, a type of a coherent state, of the constituent gravitons and inflatons. We show that this picture accounts for all the known semi-classical results, but more importantly predicts new quantum effects that are unaccounted neither by standard loop correction nor by known semi-classical non-perturbative effects. These new effects have important consequences. For example, they place an upper bound on the duration of inflation, which is in conflict with the possibility of self-reproduction and eternal inflation. We discuss various implications of these new quantum phenomena.
Relaxing the cosmological constant: a proof of concept
Energy Technology Data Exchange (ETDEWEB)
Alberte, Lasma [SISSA,Via Bonomea 265, 34136 Trieste (Italy); INFN - Sezione di Trieste,Via Valerio 2, 34127 Trieste (Italy); Creminelli, Paolo; Khmelnitsky, Andrei [Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, 34151, Trieste (Italy); Pirtskhalava, David [Institute of Physics, École Polytechnique Fédérale de Lausanne,CH-1015, Lausanne (Switzerland); Trincherini, Enrico [Scuola Normale Superiore,Piazza dei Cavalieri 7, 56126, Pisa (Italy); INFN - Sezione di Pisa,56200, Pisa (Italy)
2016-12-06
We propose a technically natural scenario whereby an initially large cosmological constant (c.c.) is relaxed down to the observed value due to the dynamics of a scalar evolving on a very shallow potential. The model crucially relies on a sector that violates the null energy condition (NEC) and gets activated only when the Hubble rate becomes sufficiently small — of the order of the present one. As a result of NEC violation, this low-energy universe evolves into inflation, followed by reheating and the standard Big Bang cosmology. The symmetries of the theory force the c.c. to be the same before and after the NEC-violating phase, so that a late-time observer sees an effective c.c. of the correct magnitude. Importantly, our model allows neither for eternal inflation nor for a set of possible values of dark energy, the latter fixed by the parameters of the theory.
Berkin, Andrew L.; Maeda, Kei-Ichi; Yokoyama, Junichi
1990-01-01
The cosmology resulting from two coupled scalar fields was studied, one which is either a new inflation or chaotic type inflation, and the other which has an exponentially decaying potential. Such a potential may appear in the conformally transformed frame of generalized Einstein theories like the Jordan-Brans-Dicke theory. The constraints necessary for successful inflation are examined. Conventional GUT models such as SU(5) were found to be compatible with new inflation, while restrictions on the self-coupling constant are significantly loosened for chaotic inflation.
Mavromatos, Nick E
2016-01-01
On the occasion of a century from the proposal of General relativity by Einstein, I attempt to tackle some open issues in modern cosmology, via a toy but non-trivial model. Specifically, I would like to link together: (i) the smallness of the cosmological constant today, (ii) the evolution of the universe from an inflationary era after the big-bang till now, and (iii) local supersymmetry in the gravitational sector (supergravity) with a broken spectrum at early eras, by making use of the concept of the "running vacuum" in the context of a simple toy model of four-dimensional N=1 supergravity. The model is characterised by dynamically broken local supersymmetry, induced by the formation of gravitino condensates in the early universe. As I will argue, there is a Starobinsky-type inflationary era characterising the broken supersymmetry phase in this model, which is compatible with the current cosmological data, provided a given constraint is satisfied among some tree-level parameters of the model and the renorma...
International Nuclear Information System (INIS)
Pandolfi, Stefania; Giusarma, Elena; Lattanzi, Massimiliano; Melchiorri, Alessandro
2010-01-01
We consider cosmological models with a non-scale-invariant spectrum of primordial perturbations and assess whether they represent a viable alternative to the concordance ΛCDM model. We find that in the framework of a model selection analysis, the WMAP and 2dF data do not provide any conclusive evidence in favor of one or the other kind of model. However, when a marginalization over the entire space of nuisance parameters is performed, models with a modified primordial spectrum and Ω Λ =0 are strongly disfavored.
Kaewkhao, Narakorn; Gumjudpai, Burin
2018-06-01
We consider, in Palatini formalism, a modified gravity of which the scalar field derivative couples to Einstein tensor. In this scenario, Ricci scalar, Ricci tensor and Einstein tensor are functions of connection field. As a result, the connection field gives rise to relation, hμν = fgμν between effective metric, hμν and the usual metric gμν where f = 1 - κϕ,αϕ,α / 2. In FLRW universe, NMDC coupling constant is limited in a range of - 2 /ϕ˙2 - 1 / 3. Power-law potentials of chaotic inflation are considered. For V ∝ϕ2 and V ∝ϕ4, it is possible to obtain tensor-to-scalar ratio lower than that of GR so that it satisfies r < 0 . 12 as constrained by Planck 2015 (Ade et al., 2016). The V ∝ϕ2 case yields acceptable range of spectrum index and r values. The quartic potential's spectrum index is disfavored by the Planck results. Viable range of κ for V ∝ϕ2 case lies in positive region, resulting in less blackhole's entropy, superluminal metric, more amount of inflation, avoidance of super-Planckian field initial value and stronger gravitational constant.
Vittorio, Nicola
2018-01-01
Modern cosmology has changed significantly over the years, from the discovery to the precision measurement era. The data now available provide a wealth of information, mostly consistent with a model where dark matter and dark energy are in a rough proportion of 3:7. The time is right for a fresh new textbook which captures the state-of-the art in cosmology. Written by one of the world's leading cosmologists, this brand new, thoroughly class-tested textbook provides graduate and undergraduate students with coverage of the very latest developments and experimental results in the field. Prof. Nicola Vittorio shows what is meant by precision cosmology, from both theoretical and observational perspectives.
Higgs-dilaton cosmology: An inflation-dark-energy connection and forecasts for future galaxy surveys
Casas, Santiago; Pauly, Martin; Rubio, Javier
2018-02-01
The Higgs-dilaton model is a scale-invariant extension of the Standard Model nonminimally coupled to gravity and containing just one additional degree of freedom on top of the Standard Model particle content. This minimalistic scenario predicts a set of measurable consistency relations between the inflationary observables and the dark-energy equation-of-state parameter. We present an alternative derivation of these consistency relations that highlights the connections and differences with the α -attractor scenario. We study how far these constraints allow one to distinguish the Higgs-dilaton model from Λ CDM and w CDM cosmologies. To this end we first analyze existing data sets using a Markov chain Monte Carlo approach. Second, we perform forecasts for future galaxy surveys using a Fisher matrix approach, both for galaxy clustering and weak lensing probes. Assuming that the best fit values in the different models remain comparable to the present ones, we show that both Euclid- and SKA2-like missions will be able to discriminate a Higgs-dilaton cosmology from Λ CDM and w CDM .
Axions in inflationary cosmology
International Nuclear Information System (INIS)
Linde, A.
1991-01-01
The problem of the cosmological constraints on the axion mass is re-examined. It is argued that in the context of inflationary cosmology the constraint m a > or approx.10 -5 eV can be avoided even when the axion perturbations produced during inflation are taken into account. It is shown also that in most axion models the effective parameter f a rapidly changes during inflation. This modifies some earlier statements concerning isothermal perturbations in the axion cosmology. A hybrid inflation scenario is proposed which combines some advantages of chaotic inflation with specific features of new and/or extended inflation. Its implications for the axion cosmology are discussed. (orig.)
Domination, Eternal Domination, and Clique Covering
Directory of Open Access Journals (Sweden)
Klostermeyer William F.
2015-05-01
Full Text Available Eternal and m-eternal domination are concerned with using mobile guards to protect a graph against infinite sequences of attacks at vertices. Eternal domination allows one guard to move per attack, whereas more than one guard may move per attack in the m-eternal domination model. Inequality chains consisting of the domination, eternal domination, m-eternal domination, independence, and clique covering numbers of graph are explored in this paper.
Eternity Variables to Simulate Specifications
Hesselink, WH; Boiten, EA; Moller, B
2002-01-01
Simulation of specifications is introduced as a unification and generalization of refinement mappings, history variables, forward simulations, prophecy variables, and backward simulations. Eternity variables are introduced as a more powerful alternative for prophecy variables and backward
International Nuclear Information System (INIS)
Antusch, S.; King, F.S.; Malinsky, M.; Velasco-Sevilla, L.; Zavala, I.
2008-04-01
We propose an entirely new class of particle physics models of inflation based on the phase transition associated with the spontaneous breaking of family symmetry responsible for the generation of the effective quark and lepton Yukawa couplings. We show that the Higgs fields responsible for the breaking of family symmetry, called flavons, are natural candidates for the inflation field in new inflation, or the waterfall fields in hybrid inflation. This opens up a rich vein of possible inflation models, all linked to the physics of flavour, with interesting cosmological and phenomenological implications. Out of these many possibilities we discuss two examples which realise flavon inflation: a model of new inflation based on the discrete non-Abelian family symmetry group A 4 or Δ 27 , and a model of hybrid inflation embedded in an existing flavour model with a continuous SU(3) family symmetry. With the inflation scale and family symmetry breaking scale below the Grand Unification Theory (GUT) scale, these classes of models are free of the monopole (and similar) problems which are often associated with the GUT phase transition. (author)
International Nuclear Information System (INIS)
Ratra, B.
1991-01-01
Estimates for the baryon-dominated epoch form of the large-scale adiabatic energy-density irregularities generated during an early scalar-field-dominated inflation epoch, in simple inflation-modified hot-big-bang models, are compared to the widely used approximate general expression, which is proportional to the large-scale, gauge-invariant part of H 2 left-angle φφ * right-angle/(Φ b ) 2 evaluated at the first Hubble radius crossing (here Φ b and φ are the spatially homogeneous and inhomogeneous parts of the scalar field, H is the Hubble parameter, and an overdot represents a derivative with respect to time). In the de Sitter inflation limit, if the inflation-epoch background scalar-field solution is an ''attractor,'' or if there is sufficient inflation before the scale of interest leaves the Hubble radius, the approximate general expression identically reproduces what we have found. It is also less than an order of magnitude away from our expression in a large fraction of the parameter space of the inflation model we study and is within 2 orders of magnitude of our result in almost all of parameter space. We also show that the more accurate general expression (which the above formula is an approximation of) identically reproduces our results in the simple models studied, provided the inflation-epoch background scalar-field solution is an ''attractor'' or if there is sufficient inflation. The approximate general formula is used to restudy energy-density inhomogeneities in the quartic-potential scalar-field de Sitter inflation model; the difference between the standard result in this model and our result in related models is traced to a difference in the form of the part of the potential used to model ''reheating'' and the end of inflation
International Nuclear Information System (INIS)
Gomez Martinez, Silvina Paola; Madriz Aguilar, Jose Edgar; Bellini, Mauricio
2007-01-01
We study gravitational waves generated during the inflationary epoch in presence of a decaying cosmological parameter on a 5D geometrical background which is Riemann flat. Two examples are considered, one with a constant cosmological parameter and the second with a decreasing one
Relaxing a large cosmological constant
International Nuclear Information System (INIS)
Bauer, Florian; Sola, Joan; Stefancic, Hrvoje
2009-01-01
The cosmological constant (CC) problem is the biggest enigma of theoretical physics ever. In recent times, it has been rephrased as the dark energy (DE) problem in order to encompass a wider spectrum of possibilities. It is, in any case, a polyhedric puzzle with many faces, including the cosmic coincidence problem, i.e. why the density of matter ρ m is presently so close to the CC density ρ Λ . However, the oldest, toughest and most intriguing face of this polyhedron is the big CC problem, namely why the measured value of ρ Λ at present is so small as compared to any typical density scale existing in high energy physics, especially taking into account the many phase transitions that our Universe has undergone since the early times, including inflation. In this Letter, we propose to extend the field equations of General Relativity by including a class of invariant terms that automatically relax the value of the CC irrespective of the initial size of the vacuum energy in the early epochs. We show that, at late times, the Universe enters an eternal de Sitter stage mimicking a tiny positive cosmological constant. Thus, these models could be able to solve the big CC problem without fine-tuning and have also a bearing on the cosmic coincidence problem. Remarkably, they mimic the ΛCDM model to a large extent, but they still leave some characteristic imprints that should be testable in the next generation of experiments.
Energy Technology Data Exchange (ETDEWEB)
Vilenkin, Alexander, E-mail: vilenkin@cosmos.phy.tufts.ed [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
2010-01-01
The 'new standard cosmology', based on the theory of inflation, has very impressive observational support. I review some outstanding problems of the new cosmology and the global view of the universe - the multiverse - that it suggests. I focus in particular on prospects for further observational tests of inflation and of the multiverse.
International Nuclear Information System (INIS)
Vilenkin, Alexander
2010-01-01
The n ew standard cosmology , based on the theory of inflation, has very impressive observational support. I review some outstanding problems of the new cosmology and the global view of the universe - the multiverse - that it suggests. I focus in particular on prospects for further observational tests of inflation and of the multiverse.
Energy Technology Data Exchange (ETDEWEB)
Antusch, S. [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, D-80805 Muenchen (Germany); King, S.F.; Malinsky, M. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Velasco-Sevilla, L. [ICTP, Strada Costiera 11, Trieste 34014 (Italy)], E-mail: lvelasco@ictp.it; Zavala, I. [CPT and IPPP, Durham University, South Road, DH1 3LE, Durham (United Kingdom)
2008-08-14
We propose an entirely new class of particle physics models of inflation based on the phase transition associated with the spontaneous breaking of family symmetry responsible for the generation of the effective quark and lepton Yukawa couplings. We show that the Higgs fields responsible for the breaking of family symmetry, called flavons, are natural candidates for the inflaton field in new inflation, or the waterfall fields in hybrid inflation. This opens up a rich vein of possibilities for inflation, all linked to the physics of flavour, with interesting cosmological and phenomenological implications. Out of these, we discuss two examples which realise flavon inflation: a model of new inflation based on the discrete non-Abelian family symmetry group A{sub 4} or {delta}{sub 27}, and a model of hybrid inflation embedded in an existing flavour model with a continuous SU(3) family symmetry. With the inflation scale and family symmetry breaking scale below the Grand Unification Theory (GUT) scale, these classes of models are free of the monopole (and similar) problems which are often associated with the GUT phase transition.
International Nuclear Information System (INIS)
Antusch, S.; King, S.F.; Malinsky, M.; Velasco-Sevilla, L.; Zavala, I.
2008-01-01
We propose an entirely new class of particle physics models of inflation based on the phase transition associated with the spontaneous breaking of family symmetry responsible for the generation of the effective quark and lepton Yukawa couplings. We show that the Higgs fields responsible for the breaking of family symmetry, called flavons, are natural candidates for the inflaton field in new inflation, or the waterfall fields in hybrid inflation. This opens up a rich vein of possibilities for inflation, all linked to the physics of flavour, with interesting cosmological and phenomenological implications. Out of these, we discuss two examples which realise flavon inflation: a model of new inflation based on the discrete non-Abelian family symmetry group A 4 or Δ 27 , and a model of hybrid inflation embedded in an existing flavour model with a continuous SU(3) family symmetry. With the inflation scale and family symmetry breaking scale below the Grand Unification Theory (GUT) scale, these classes of models are free of the monopole (and similar) problems which are often associated with the GUT phase transition
Costa, João L.; Girão, Pedro M.; Natário, José; Silva, Jorge Drumond
2018-03-01
In this paper we study the spherically symmetric characteristic initial data problem for the Einstein-Maxwell-scalar field system with a positive cosmological constant in the interior of a black hole, assuming an exponential Price law along the event horizon. More precisely, we construct open sets of characteristic data which, on the outgoing initial null hypersurface (taken to be the event horizon), converges exponentially to a reference Reissner-Nördstrom black hole at infinity. We prove the stability of the radius function at the Cauchy horizon, and show that, depending on the decay rate of the initial data, mass inflation may or may not occur. In the latter case, we find that the solution can be extended across the Cauchy horizon with continuous metric and Christoffel symbols in {L^2_{loc}} , thus violating the Christodoulou-Chruściel version of strong cosmic censorship.
Narlikar, Jayant Vishnu
2002-01-01
The third edition of this successful textbook is fully updated and includes important recent developments in cosmology. It begins with an introduction to cosmology and general relativity, and goes on to cover the mathematical models of standard cosmology. The physical aspects of cosmology, including primordial nucleosynthesis, the astroparticle physics of inflation, and the current ideas on structure formation are discussed. Alternative models of cosmology are reviewed, including the model of Quasi-Steady State Cosmology, which has recently been proposed as an alternative to Big Bang Cosmology.
International Nuclear Information System (INIS)
Oh, P.; Chicago Univ., IL
1986-01-01
Cosmological solutions with three exponentially expanding space dimensions in the N=1 supersymmetric Yang-Mills supergravity system are found under the assumption of gluino and ''subgravitino'' condensation. The potential has a long flat region providing sufficient inflation. (orig.)
García-Bellido, J
1998-01-01
We propose a new model of inflation based on the soft-breaking of N=2 supersymmetric SU(2) Yang-Mills theory. The advantage of such a model is the fact that we can write an exact expression for the effective scalar potential, including non-perturbative effects, which preserves the analyticity and duality properties of the Seiberg-Witten solution. We find that the scalar condensate that plays the role of the inflaton can drive a long period of cosmological expansion, produce the right amount of temperature anisotropies in the microwave background, and end inflation when the monopole acquires a vacuum expectation value. Duality properties relate the weak coupling Higgs region where inflation takes place with the strong coupling monopole region, where reheating occurs, creating particles corresponding to the light degrees of freedom in the true vacuum.
García-Bellido, J
2003-01-01
In this talk I will review the present status of inflationary cosmology and its emergence as the basic paradigm behind the Standard Cosmological Model, with parameters determined today at better than 10% level from CMB and LSS observations. I will also discuss the recent theoretical developments on the process of reheating after inflation and model building based on string theory and D-branes.
International Nuclear Information System (INIS)
Zavala, I.
2008-01-01
A new class of particle physics models of inflation based on the phase transition associated with the spontaneous breaking of family symmetry is proposed. The Higgs fields responsible for the breaking of family symmetry, the flavons, are natural inflaton candidates or waterfall fields in hybrid inflation. This opens up a rich vein of possible inflation models, all linked to the physics of flavour, with several interesting cosmological implications.
Srivastava, S. K.
2008-01-01
Here, cosmology is obtained from the variable gravitational constant $ G \\propto \\phi^{-2}$ with $ \\phi(x) $ being a scalar and its fluctuations around the ground state. The gravitational action contains Einstein-Hilbert like term with variable $ G $, kinetic energy and self-interaction potential for $ \\phi(x) $. Two phase transitions take place in this model. The first one takes place at the GUT (grand unified theory) scale $ \\sim 2.45 \\times 10^{14}{\\rm GeV} $, when the early universe exits...
White holes and eternal black holes
International Nuclear Information System (INIS)
Hsu, Stephen D H
2012-01-01
We investigate isolated white holes surrounded by vacuum, which correspond to the time reversal of eternal black holes that do not evaporate. We show that isolated white holes produce quasi-thermal Hawking radiation. The time reversal of this radiation, incident on a black hole precursor, constitutes a special preparation that will cause the black hole to become eternal. (paper)
Deviation from Standard Inflationary Cosmology and the Problems in Ekpyrosis
Tseng, Chien-Yao
There are two competing models of our universe right now. One is Big Bang with inflation cosmology. The other is the cyclic model with ekpyrotic phase in each cycle. This paper is divided into two main parts according to these two models. In the first part, we quantify the potentially observable effects of a small violation of translational invariance during inflation, as characterized by the presence of a preferred point, line, or plane. We explore the imprint such a violation would leave on the cosmic microwave background anisotropy, and provide explicit formulas for the expected amplitudes ( alma*l'm') of the spherical-harmonic coefficients. We then provide a model and study the two-point correlation of a massless scalar (the inflaton) when the stress tensor contains the energy density from an infinitely long straight cosmic string in addition to a cosmological constant. Finally, we discuss if inflation can reconcile with the Liouville's theorem as far as the fine-tuning problem is concerned. In the second part, we find several problems in the cyclic/ekpyrotic cosmology. First of all, quantum to classical transition would not happen during an ekpyrotic phase even for superhorizon modes, and therefore the fluctuations cannot be interpreted as classical. This implies the prediction of scale-free power spectrum in ekpyrotic/cyclic universe model requires more inspection. Secondly, we find that the usual mechanism to solve fine-tuning problems is not compatible with eternal universe which contains infinitely many cycles in both direction of time. Therefore, all fine-tuning problems including the flatness problem still asks for an explanation in any generic cyclic models.
International Nuclear Information System (INIS)
Turner, M.S.
1983-01-01
The hot big bang cosmology provides a reliable accounting of the evolution of the Universe from -- 0.01 s after 'the bang' until the present (10-20 Byr after 'the bang'). This is a truly impressive achievement. There are, however, a handful of very fundamental 'cosmological facts' which the model by itself fails to elucidate. They include: the large-scale homogeneity, the isotropy, the small-scale inhomogeneity, the near critical expansion rate, the predominance of matter, the 'monopole problem', and the extremely tiny value of the present cosmological term. Inflation makes the present state of the observable Universe virtually insensitive to the initial state of the Universe. Unfortunately, at present there is no model of new inflation which both resolves the cosmological puzzles and leads to sensible particle physics. A general prescription for the cosmologically-desirable Higgs potential does exist
Computational complexity of the landscape II-Cosmological considerations
Denef, Frederik; Douglas, Michael R.; Greene, Brian; Zukowski, Claire
2018-05-01
We propose a new approach for multiverse analysis based on computational complexity, which leads to a new family of "computational" measure factors. By defining a cosmology as a space-time containing a vacuum with specified properties (for example small cosmological constant) together with rules for how time evolution will produce the vacuum, we can associate global time in a multiverse with clock time on a supercomputer which simulates it. We argue for a principle of "limited computational complexity" governing early universe dynamics as simulated by this supercomputer, which translates to a global measure for regulating the infinities of eternal inflation. The rules for time evolution can be thought of as a search algorithm, whose details should be constrained by a stronger principle of "minimal computational complexity". Unlike previously studied global measures, ours avoids standard equilibrium considerations and the well-known problems of Boltzmann Brains and the youngness paradox. We also give various definitions of the computational complexity of a cosmology, and argue that there are only a few natural complexity classes.
Li, Bohua; Shapiro, Paul R.; Rindler-Daller, Tanja
2017-09-01
We consider an alternative to weakly interacting massive particle (WIMP) cold dark matter (CDM)—ultralight bosonic dark matter (m ≳10-22 eV /c2) described by a complex scalar field (SFDM) with a global U (1 ) symmetry—for which the comoving particle number density or charge density is conserved after particle production during standard reheating. We allow for a repulsive self-interaction. In a Λ SFDM universe, SFDM starts out relativistic, evolving from stiff (w =1 ) to radiation-like (w =1 /3 ), before becoming nonrelativistic at late times (w =0 ). Thus, before the familiar radiation-dominated era, there is an earlier era of stiff-SFDM domination. During both the stiff-SFDM-dominated and radiation-dominated eras, the expansion rate is higher than in Λ CDM . The SFDM particle mass m and quartic self-interaction coupling strength λ are therefore constrained by cosmological observables, particularly Neff, the effective number of neutrino species during big bang nucleosynthesis, and zeq, the redshift of matter-radiation equality. Furthermore, since the stochastic gravitational-wave background (SGWB) from inflation is amplified during the stiff-SFDM-dominated era, it can contribute a radiation-like component large enough to affect these observables by further boosting the expansion rate after the stiff era ends. Remarkably, this same amplification makes detection of the SGWB possible at high frequencies by current laser interferometer experiments, e.g., aLIGO/Virgo and LISA. For SFDM particle parameters that satisfy these cosmological constraints, the amplified SGWB is detectable by LIGO for a broad range of reheat temperatures Treheat, for values of the tensor-to-scalar ratio r currently allowed by cosmic microwave background polarization measurements. For a given r and λ /(m c2)2, the marginally allowed Λ SFDM model for each Treheat has the smallest m that satisfies the cosmological constraints, and maximizes the present SGWB energy density for that
A critical review of inflation
Turok, N G
2002-01-01
The theory of cosmic inflation offers an attractive resolution of some of the great paradoxes in cosmology: why the universe is so large, flat and uniform on large scales, and how density variations arose. Inflation has rightly dominated cosmological thinking for the past two decades, helping stimulate the development of high-precision observational programmes. The survival of simple inflationary models in the face of an impressive observational onslaught has been interpreted as convincing evidence of the correctness of the basic idea. In this paper, I review inflation, but highlight its weaknesses, explaining my reasons for believing that a more complete theory may supersede inflation without necessarily incorporating it.
A critical review of inflation
International Nuclear Information System (INIS)
Turok, Neil
2002-01-01
The theory of cosmic inflation offers an attractive resolution of some of the great paradoxes in cosmology: why the universe is so large, flat and uniform on large scales, and how density variations arose. Inflation has rightly dominated cosmological thinking for the past two decades, helping stimulate the development of high-precision observational programmes. The survival of simple inflationary models in the face of an impressive observational onslaught has been interpreted as convincing evidence of the correctness of the basic idea. In this paper, I review inflation, but highlight its weaknesses, explaining my reasons for believing that a more complete theory may supersede inflation without necessarily incorporating it
International Nuclear Information System (INIS)
Green, Dan
2014-01-01
The last few years have yielded remarkable discoveries in physics. In particle physics it appears that a fundamental scalar field exists. The Higgs boson is measured to have a mass of about 126 GeV and to have spin zero and positive parity. The Higgs field is the first fundamental scalar to be discovered in physics. The Cosmic Microwave Background, CMB, is known to have a uniform temperature to parts per 10 5 , but has well measured fluctuations, which are thought to evolve gravitationally to provide the seeds of the current structure of the Universe. In addition, the Universe appears to contain, at present, an unknown ''dark energy'', which is presently the majority energy density of the Universe, larger than either matter or radiation. This may, indeed, be a fundamental scalar field like the Higgs. ''Big Bang'' (BB) cosmology is a very successful ''standard model'' in cosmology. However, it cannot explain the uniformity of the CMB because the CMB consists of many regions not causally connected in the context of the BB model. In addition, the Universe appears to be spatially flat. However, in BB cosmology the present spatial curvature is not stable, so that the initial conditions for BB cosmology would need to be fantastically fine-tuned in order to successfully predict the presently small value of the observed curvature. These issues for BB cosmology have led to the hypothesis of ''inflation'' which postulates an unknown scalar field, not presumably the Higgs field or the dark energy, which causes an exponential expansion of the Universe at very early times. This attractive hypothesis can account for the problems in BB cosmology of flatness and causal CMB connectivity. In addition, the quantum fluctuations of this postulated field provide a natural explanation of the CMB fluctuations which are the seeds of the structure of galaxies. Researchers are now searching for gravitational
International Nuclear Information System (INIS)
Chialva, Diego; Danielsson, Ulf H
2008-01-01
This paper represents an in-depth treatment of the chain inflation scenario. We fully determine the evolution of the universe in the model, the conditions necessary in order to have a successful inflationary period, and the matching with the observational results regarding the cosmological perturbations. We study in great detail, and in general, the dynamics of the background, as well as the mechanism of generation of the perturbations. We also find an explicit formula for the spectrum of adiabatic perturbations. Our results prove that chain inflation is a viable model for solving the horizon, entropy and flatness problems of standard cosmology and for generating the right amount of adiabatic cosmological perturbations. The results are radically different from those found in previous works on the subject. Finally, we argue that there is a natural way to embed chain inflation into flux compactified string theory. We discuss the details of the implementation and how to fit observations
The Future of Theoretical Physics and Cosmology
Gibbons, G. W.; Shellard, E. P. S.; Rankin, S. J.
2009-08-01
: 31. Adventures in de Sitter space Raphael Bousso; 32. de Sitter space in non-critical string theory Andrew Strominger; 33. Supergravity, M theory and cosmology Renata Kallosh; Part VIII. Quantum Cosmology: 34. The state of the universe James B. Hartle; 35. Quantum cosmology Don Page; 36. Quantum cosmology and eternal inflation A. Vilenkin; 37. Probability in the deterministic theory known as quantum mechanics Bryce de Witt; 38. The interpretation of quantum cosmology and the problem of time J. Halliwell; 39. What local supersymmetry can do for quantum cosmology Peter D'Eath; Part IX. Cosmology: 40. Inflation and cosmological perturbations Alan Guth; 41. The future of cosmology: observational and computational prospects Paul Shellard; 42. The ekpyrotic universe and its cyclic extension Neil Turok; 43. Inflationary theory versus the ekpyrotic/cyclic scenario Andrei Linde; 44. Brane (new) worlds Pierre Binetruy; 45. Publications of Stephen Hawking; Index.
Inflation targeting and core inflation
Julie Smith
2005-01-01
This paper examines the interaction of core inflation and inflation targeting as a monetary policy regime. Interest in core inflation has grown because of inflation targeting. Core inflation is defined in numerous ways giving rise to many potential measures; this paper defines core inflation as the best forecaster of inflation. A cross-country study finds before the start of inflation targeting, but not after, core inflation differs between non-inflation targeters and inflation targeters. Thr...
The Universe, Time, Eternity and Infinity
Directory of Open Access Journals (Sweden)
Lolaev T. P.
2013-04-01
Full Text Available The conceptions of «universe», «eternity», «time» and «infinity» belong to the list of the most fundamental and complex characteristics of the matter. The concepts of "universe", "eternity", "time" and "infinity" is defined in article in fundamentally new interpretation. This was made possible thanks to the identification by the author the nature of time, and formulation and theoretically and experimentally justification of the Law of the Universe functioning.
International Nuclear Information System (INIS)
Chimento, L P; Forte, M; Devecchi, F P; Kremer, G M; Ribas, M O; Samojeden, L L
2011-01-01
In this work we review if fermionic sources could be responsible for accelerated periods during the evolution of a FRW universe. In a first attempt, besides the fermionic source, a matter constituent would answer for the decelerated periods. The coupled differential equations that emerge from the field equations are integrated numerically. The self-interaction potential of the fermionic field is considered as a function of the scalar and pseudo-scalar invariants. It is shown that the fermionic field could behave like an inflaton field in the early universe, giving place to a transition to a matter dominated (decelerated) period. In a second formulation we turn our attention to analytical results, specifically using the idea of form-invariance transformations. These transformations can be used for obtaining accelerated cosmologies starting with conventional cosmological models. Here we reconsider the scalar field case and extend the discussion to fermionic fields. Finally we investigate the role of a Dirac field in a Brans-Dicke (BD) context. The results show that this source, in combination with the BD scalar, promote a final eternal accelerated era, after a matter dominated period.
Indian Academy of Sciences (India)
at different distances (that is, at different epochs in the past) to come to this ... that the expansion started billions of years ago from an explosive Big Bang. Recent research sheds new light on the key cosmological question about the distant ...
Chamcham, Khalil; Silk, Joseph; Barrow, John D.; Saunders, Simon
2017-04-01
Part I. Issues in the Philosophy of Cosmology: 1. Cosmology, cosmologia and the testing of cosmological theories George F. R. Ellis; 2. Black holes, cosmology and the passage of time: three problems at the limits of science Bernard Carr; 3. Moving boundaries? - comments on the relationship between philosophy and cosmology Claus Beisbart; 4. On the question why there exists something rather than nothing Roderich Tumulka; Part II. Structures in the Universe and the Structure of Modern Cosmology: 5. Some generalities about generality John D. Barrow; 6. Emergent structures of effective field theories Jean-Philippe Uzan; 7. Cosmological structure formation Joel R. Primack; 8. Formation of galaxies Joseph Silk; Part III. Foundations of Cosmology: Gravity and the Quantum: 9. The observer strikes back James Hartle and Thomas Hertog; 10. Testing inflation Chris Smeenk; 11. Why Boltzmann brains do not fluctuate into existence from the de Sitter vacuum Kimberly K. Boddy, Sean M. Carroll and Jason Pollack; 12. Holographic inflation revised Tom Banks; 13. Progress and gravity: overcoming divisions between general relativity and particle physics and between physics and HPS J. Brian Pitts; Part IV. Quantum Foundations and Quantum Gravity: 14. Is time's arrow perspectival? Carlo Rovelli; 15. Relational quantum cosmology Francesca Vidotto; 16. Cosmological ontology and epistemology Don N. Page; 17. Quantum origin of cosmological structure and dynamical reduction theories Daniel Sudarsky; 18. Towards a novel approach to semi-classical gravity Ward Struyve; Part V. Methodological and Philosophical Issues: 19. Limits of time in cosmology Svend E. Rugh and Henrik Zinkernagel; 20. Self-locating priors and cosmological measures Cian Dorr and Frank Arntzenius; 21. On probability and cosmology: inference beyond data? Martin Sahlén; 22. Testing the multiverse: Bayes, fine-tuning and typicality Luke A. Barnes; 23. A new perspective on Einstein's philosophy of cosmology Cormac O
Rajantie, Arttu
2018-03-06
The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).
Rajantie, Arttu
2018-01-01
The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue `Higgs cosmology'.
Fluctuations in models with primordial inflation
International Nuclear Information System (INIS)
Kahn, R.; Brandenberger, R.
1984-01-01
The recently proposed general framework for calculating the growth of primordial energy density fluctuations in cosmological models is applied to two models of phenomenological interest in which the cosmological evolution differs crucially from that in new inflationary universe models. Both in a model of primordial supersymmetric inflation and in Linde's proposal of chaotic inflation we verify the conjectured results. (orig.)
Measures, Probability and Holography in Cosmology
Phillips, Daniel
comment on the general implications of this view, and specifically question the application of classical probability theory to cosmology in cases where key questions are known to have no quantum answer. We argue that the ideas developed here may offer a way out of the notorious measure problems of eternal inflation. The fourth project looks at finite universes as alternatives to multiverse theories of cosmology. We compare two holographic arguments that impose especially strong bounds on the amount of inflation. One comes from the de Sitter Equilibrium cosmology and the other from the work of Banks and Fischler. We find that simple versions of these two approaches yield the same bound on the number of e-foldings. A careful examination reveals that while these pictures are similar in spirit, they are not necessarily identical prescriptions. We apply the two pictures to specific cosmologies which expose potentially important differences and which also demonstrate ways these seemingly simple proposals can be tricky to implement in practice.
International Nuclear Information System (INIS)
Feng, Jonathan L.
2005-01-01
Cosmology now provides unambiguous, quantitative evidence for new particle physics. I discuss the implications of cosmology for supersymmetry and vice versa. Topics include: motivations for supersymmetry; supersymmetry breaking; dark energy; freeze out and WIMPs; neutralino dark matter; cosmologically preferred regions of minimal supergravity; direct and indirect detection of neutralinos; the DAMA and HEAT signals; inflation and reheating; gravitino dark matter; Big Bang nucleosynthesis; and the cosmic microwave background. I conclude with speculations about the prospects for a microscopic description of the dark universe, stressing the necessity of diverse experiments on both sides of the particle physics/cosmology interface
Roos, Matts
2003-01-01
The Third Edition of the hugely successful Introduction to Cosmology provides a concise, authoritative study of cosmology at an introductory level. Starting from elementary principles and the history of cosmology, the text carefully guides the student on to curved spacetimes, general relativity, black holes, cosmological models, particles and symmetries, and phase transitions. Extensively revised, this latest edition includes broader and updated coverage of distance measures, gravitational lensing and waves, dark energy and quintessence, the thermal history of the Universe, inflation,
Inflation and the Higgs Scalar
Energy Technology Data Exchange (ETDEWEB)
Green, Dan [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2014-12-05
This note makes a self-contained exposition of the basic facts of big bang cosmology as they relate to inflation. The fundamental problems with that model are then explored. A simple scalar model of inflation is evaluated which provides the solution of those problems and makes predictions which will soon be definitively tested. The possibility that the recently discovered fundamental Higgs scalar field drives inflation is explored.
Energy Technology Data Exchange (ETDEWEB)
Green, Dan [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2014-03-01
The last few years have yielded remarkable discoveries in physics. In particle physics it appears that a fundamental scalar field exists. The Higgs boson is measured to have a mass of about 126 GeV and to have spin zero and positive parity. The Higgs field is the first fundamental scalar to be discovered in physics. The Cosmic Microwave Background, CMB, is known to have a uniform temperature to parts per 10^{5}, but has well measured fluctuations, which are thought to evolve gravitationally to provide the seeds of the current structure of the Universe. In addition, the Universe appears to contain, at present, an unknown “dark energy”, which is presently the majority energy density of the Universe, larger than either matter or radiation. This may, indeed, be a fundamental scalar field like the Higgs. “Big Bang” (BB) cosmology is a very successful “standard model” in cosmology. However, it cannot explain the uniformity of the CMB because the CMB consists of many regions not causally connected in the context of the BB model. In addition, the Universe appears to be spatially flat. However, in BB cosmology the present spatial curvature is not stable, so that the initial conditions for BB cosmology would need to be fantastically fine-tuned in order to successfully predict the presently small value of the observed curvature. These issues for BB cosmology have led to the hypothesis of “inflation” which postulates an unknown scalar field, not presumably the Higgs field or the dark energy, which causes an exponential expansion of the Universe at very early times. This attractive hypothesis can account for the problems in BB cosmology of flatness and causal CMB connectivity. In addition, the quantum fluctuations of this postulated field provide a natural explanation of the CMB fluctuations which are the seeds of the structure of galaxies. Researchers are now searching for gravitational waves imprinted on the CMB. These would be a “smoking gun” for
Inflation from extra dimensions
International Nuclear Information System (INIS)
Barr, S.M.
1984-01-01
Recently there has been growing interest (1) in the possibility that the universe could have more than four dimensions. Aside from any light this may shed on problems in particle physics, if true it would undoubtedly have important implications for early cosmology. A rather speculative but very appealing possibility suggested by D. Sahdev and by E. Alvarez and B. Gavela is that the gravitational collapse of extra spatial dimensions could drive an inflation of ordinary space. This kind of inflationary cosmology would be quite different from the inflationary cosmologies now so intensively studied which are supposed to result from changes in vacuum energy during phase transitions in the early universe. In our work we examine the physics of these Kaluza-Klein inflationary cosmologies and come to three main conclusions. (1) It is desirable to have many extra dimensions, many being of order forty or fifty. (2) For models which give a realistically large inflation almost all of this inflation occurs in a period when quantum gravity is certainly important. This means that Einstein's equations cannot be used to calculate the details of this inflationary period. (3) Under plausible assumptions one may argue from the second law of thermodynamics that given appropriate initial conditions a large inflation will occur even when details of the inflationary phase cannot be calculated classically
Extended inflation with nonminimally coupled inflation field
International Nuclear Information System (INIS)
Panchapakesan, N.; Sethi, S.K.
1992-01-01
In this paper, an extended inflation model, in which the inflation field is nonminimally coupled to the gravity, is discussed. It is shown that the nucleation rate of bubbles, during a phase transition in the inflaton field, can increase as the transition proceeds for a wide range of parameters of the inflaton potential. The bounce action for three possible cases - the strong gravity regime, the thick-walled Coleman-DeLuccia bubbles and the thin-walled bubbles - is evaluated. The resulting bubble distribution for all the cases is shown to be in conformity with cosmological constraints for ω < 500
Inflation and cosmic strings: Two mechanisms for producing structure in the universe
International Nuclear Information System (INIS)
Brandenberger, R.
1987-01-01
Contents: Introduction; Big Bang Cosmology and its Problems; The Old and the New Inflationary Universe; The Onset of Inflation; Chaotic Inflation; The Origin of Small Scale Structure in Inflationary Universe Models: Generation of Perturbations; Gauge Invariant Analysis of Classical Perturbations; Evolution of Perturbations in Inflationary Universe Models; Cosmological Constrains on Inflationary Universe Models; Beyond the Simplest Models of Inflation; Generalized Inflation (Kaluza-Klein Inflation, Inflation in Induced Gravity Models and in Superstring Theories); Quantum Cosmology and Inflation; Inflation and Cosmic Strings: A Comparison between Two Mechanisms for Forming Structures in the Early Universe
Roberts, Alex
2016-08-01
Recently, a new framework for describing the multiverse has been proposed which is based on the principles of quantum mechanics. The framework allows for well-defined predictions, both regarding global properties of the universe and outcomes of particular experiments, according to a single probability formula. This provides complete unification of the eternally inflating multiverse and many worlds in quantum mechanics. We elucidate how cosmological parameters can be calculated in this framework, and study the probability distribution for the value of the cosmological constant. We consider both positive and negative values, and find that the observed value is consistent with the calculated distribution at an order of magnitude level. In particular, in contrast to the case of earlier measure proposals, our framework prefers a positive cosmological constant over a negative one. These results depend only moderately on how we model galaxy formation and life evolution therein. We explore supersymmetric theories in which the Higgs mass is boosted by the non-decoupling D-terms of an extended U(1) X gauge symmetry, defined here to be a general linear combination of hypercharge, baryon number, and lepton number. Crucially, the gauge coupling, gX, is bounded from below to accommodate the Higgs mass, while the quarks and leptons are required by gauge invariance to carry non-zero charge under U(1)X. This induces an irreducible rate, sigmaBR, for pp → X → ll relevant to existing and future resonance searches, and gives rise to higher dimension operators that are stringently constrained by precision electroweak measurements. Combined, these bounds define a maximally allowed region in the space of observables, (sigmaBR, mX), outside of which is excluded by naturalness and experimental limits. If natural supersymmetry utilizes non-decoupling D-terms, then the associated X boson can only be observed within this window, providing a model independent 'litmus test' for this broad
Bumps on the Road to Here (from Eternity
Directory of Open Access Journals (Sweden)
Eric Winsberg
2012-02-01
Full Text Available In his recent book, From Eternity to Here, and in other more technical papers, Sean Carroll (partly in collaboration with Jennifer Chen has put forward an intriguing new way to think about the origin of the Universe. His approach, in a nutshell, is to raise certain worries about a standard Boltzmannian picture of statistical mechanics, and to present certain commitments that he thinks we ought to hold—commitments that the standard picture doesn’t share. He then proposes a cosmological model—one that purports to give us insight into what sort of process brought about the “initial state” of the universe—that can uniquely accommodate those commitments. The conclusion of Carroll’s argument is that statistical mechanical reasoning provides grounds for provisionally accepting that cosmological model. My goal in this paper is to reconstruct and critically assess this proposal. I argue that “statistical cosmology” requires a careful balance of philosophical intuitions and commitments against technical, scientific considerations; how much stock we ought to place in these intuitions and commitments should depend on where they lead us—those that lead us astray scientifically might well be in need of philosophical re‑examination.
International Nuclear Information System (INIS)
Matsuda, Tomohiro
2010-01-01
We describe new scenarios for generating curvature perturbations when inflaton (curvaton) has significant interactions. We consider a ''spot'', which arises from interactions associated with an enhanced symmetric point (ESP) on the trajectory. Our first example uses the spot to induce a gap in the field equation. We observe that the gap in the field equation may cause generation of curvature perturbation if it does not appear simultaneous in space. The mechanism is similar to the scenario of inhomogeneous phase transition. Then we observe that the spot interactions may initiate warm inflation in the cold Universe. Creation of cosmological perturbation is discussed in relation to the inflaton dynamics and the modulation associated with the spot interactions
Local Operators in the Eternal Black Hole
Papadodimas, Kyriakos; Raju, Suvrat
2015-01-01
In the AdS/CFT correspondence, states obtained by Hamiltonian evolution of the thermofield doubled state are also dual to an eternal black-hole geometry, which is glued to the boundary with a time shift generated by a large diffeomorphism. We describe gauge-invariant relational observables that
Eternal peace and world citizen order
Directory of Open Access Journals (Sweden)
Lolić Marinko V.
2004-01-01
Full Text Available In this paper the author examines the key principles of Kant's conception of eternal peace and the possibility of an international legal order grounded in Reason. The central segment of the paper consists of an analysis of the problem of mediation between Kant's normative theory and political practice.
Axion cold dark matter in nonstandard cosmologies
International Nuclear Information System (INIS)
Visinelli, Luca; Gondolo, Paolo
2010-01-01
We study the parameter space of cold dark matter axions in two cosmological scenarios with nonstandard thermal histories before big bang nucleosynthesis: the low-temperature reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmology. We show that the axion velocity dispersion may be used to distinguish some of these nonstandard cosmologies. Thus, axion cold dark matter may be a good probe of the history of the Universe before big bang nucleosynthesis.
Ellis, John; Nanopoulos, Dimitri V.; Olive, Keith A.
2016-01-01
Supersymmetry is the most natural framework for physics above the TeV scale, and the corresponding framework for early-Universe cosmology, including inflation, is supergravity. No-scale supergravity emerges from generic string compactifications and yields a non-negative potential, and is therefore a plausible framework for constructing models of inflation. No-scale inflation yields naturally predictions similar to those of the Starobinsky model based on $R + R^2$ gravity, with a tilted spectrum of scalar perturbations: $n_s \\sim 0.96$, and small values of the tensor-to-scalar perturbation ratio $r < 0.1$, as favoured by Planck and other data on the cosmic microwave background (CMB). Detailed measurements of the CMB may provide insights into the embedding of inflation within string theory as well as its links to collider physics.
Ellis, John; Garcia, Marcos A. G.; Nanopoulos, Dimitri V.; Olive, Keith A.
2016-05-01
Supersymmetry is the most natural framework for physics above the TeV scale, and the corresponding framework for early-Universe cosmology, including inflation, is supergravity. No-scale supergravity emerges from generic string compactifications and yields a non-negative potential, and is therefore a plausible framework for constructing models of inflation. No-scale inflation yields naturally predictions similar to those of the Starobinsky model based on R+{R}2 gravity, with a tilted spectrum of scalar perturbations: {n}s∼ 0.96, and small values of the tensor-to-scalar perturbation ratio r\\lt 0.1, as favoured by Planck and other data on the cosmic microwave background (CMB). Detailed measurements of the CMB may provide insights into the embedding of inflation within string theory as well as its links to collider physics.
Wilczek, Frank; Turner, Michael S.
1990-09-01
If Peccei-Quinn (PQ) symmetry is broken after inflation, the initial axion angle is a random variable on cosmological scales; based on this fact, estimates of the relic-axion mass density give too large a value if the axion mass is less than about 10-6 eV. This bound can be evaded if the Universe underwent inflation after PQ symmetry breaking and if the observable Universe happens to be a region where the initial axion angle was atypically small, .1 . (ma/10-6eV)0.59. We show consideration of fluctuations induced during inflation severely constrains the latter alternative.
International Nuclear Information System (INIS)
Turner, M.S.; Wilczek, F.
1991-01-01
If Peccei-Quinn (PQ) symmetry is broken after inflation, the initial axion angle is a random variable on cosmological scales; based on this fact, estimates of the relic-axion mass density give too large a value if the axion mass is less than about 10 -6 eV. This bound can be evaded if the Universe underwent inflation after PQ symmetry breaking and if the observable Universe happens to be a region where the initial axion angle was atypically small, θ 1 approx-lt[m a /10 -6 eV 0.59 .] We show consideration of fluctuations induced during inflation severely constrains the latter alternative
Cosmology for high energy physicists
International Nuclear Information System (INIS)
Albrecht, A.
1987-11-01
The standard big bang model of cosmology is presented. Although not perfect, its many successes make it a good starting point for most discussions of cosmology. Places are indicated where well understood laboratory physics is incorporated into the big bang, leading to successful predictions. Much less established aspects of high energy physics and some of the new ideas they have introduced into the field of cosmology are discussed, such as string theory, inflation and monopoles. 49 refs., 5 figs
International Nuclear Information System (INIS)
Nojiri, S; Odintsov, S D; Oikonomou, V K
2016-01-01
We combine the unimodular gravity and mimetic gravity theories into a unified theoretical framework, which is proposed to provide a suggestive proposal for a framework that may assist in the discussion and search for a solution to the cosmological constant problem and the dark matter issue. After providing the formulation of the unimodular mimetic gravity and investigating all the new features that the vacuum unimodular gravity implies, by using the underlying reconstruction method, we realize some well known cosmological evolutions, with some of these being exotic for the ordinary Einstein–Hilbert gravity. Specifically we provide the vacuum unimodular mimetic gravity description of the de Sitter cosmology and of the perfect fluid with constant equation of state cosmology. As we demonstrate, these cosmologies can be realized by vacuum mimetic unimodular gravity, without the existence of any matter fluid source. Moreover, we investigate how cosmologically viable cosmologies, which are compatible with the recent observational data, can be realized by the vacuum unimodular mimetic gravity. Since in some cases, a graceful exit from inflation problem might exist, we provide a qualitative description of the mechanism that can potentially generate the graceful exit from inflation in these theories, by searching for the unstable de Sitter solutions in the context of unimodular mimetic theories of gravity. (paper)
International Nuclear Information System (INIS)
Verde, L.
2011-01-01
This is the summary of two lectures that aim to give an overview of cosmology. I will not try to be toa rigorous in derivations, nor to give a full historical overview. The idea is to provide a 'taste' of cosmology and some of the interesting topics it covers. The standard cosmological model is presented and I highlight the successes of cosmology over the past decade or so. Keys to the development of the standard cosmological model are observations of the cosmic microwave background and of large-scale structure, which are introduced. Inflation and dark energy and the outlook for the future are also discussed. Slides from the lectures are available from the school web site: physicschool.web.cern.ch/PhysicSchool/CLASHEP/CLASHEP2011/. (author)
Classical and quantum cosmology
Calcagni, Gianluca
2017-01-01
This comprehensive textbook is devoted to classical and quantum cosmology, with particular emphasis on modern approaches to quantum gravity and string theory and on their observational imprint. It covers major challenges in theoretical physics such as the big bang and the cosmological constant problem. An extensive review of standard cosmology, the cosmic microwave background, inflation and dark energy sets the scene for the phenomenological application of all the main quantum-gravity and string-theory models of cosmology. Born of the author's teaching experience and commitment to bridging the gap between cosmologists and theoreticians working beyond the established laws of particle physics and general relativity, this is a unique text where quantum-gravity approaches and string theory are treated on an equal footing. As well as introducing cosmology to undergraduate and graduate students with its pedagogical presentation and the help of 45 solved exercises, this book, which includes an ambitious bibliography...
Verde, L.
2013-06-27
This is the summary of two lectures that aim to give an overview of cosmology. I will not try to be too rigorous in derivations, nor to give a full historical overview. The idea is to provide a "taste" of cosmology and some of the interesting topics it covers. The standard cosmological model is presented and I highlight the successes of cosmology over the past decade or so. Keys to the development of the standard cosmological model are observations of the cosmic microwave background and of large-scale structure, which are introduced. Inflation and dark energy and the outlook for the future are also discussed. Slides from the lectures are available from the school website: physicschool.web.cern.ch/PhysicSchool/CLASHEP/CLASHEP2011/.
Ellis, John; Gonzalo, Tomás E.; Harz, Julia; Huang, Wei-Chih
2015-01-01
We analyse the prospects for constructing hybrid models of inflation that provide a dynamical realisation of the apparent closeness between the supersymmetric GUT scale and the possible scale of cosmological inflation. In the first place, we consider models based on the flipped SU(5)×U(1) gauge group, which has no magnetic monopoles. In one model, the inflaton is identified with a sneutrino field, and in the other model it is a gauge singlet. In both cases we find regions of the model paramet...
International Nuclear Information System (INIS)
Chimento, Luis P.
2002-01-01
We find the group of symmetry transformations under which the Einstein equations for the spatially flat Friedmann-Robertson-Walker universe are form invariant. They relate the energy density and the pressure of the fluid to the expansion rate. We show that inflation can be obtained from nonaccelerated scenarios by a symmetry transformation. We derive the transformation rule for the spectrum and spectral index of the curvature perturbations. Finally, the group is extended to investigate inflation in the anisotropic Bianchi type-I spacetime and the brane-world cosmology
Supersymmetric inflation: Recent progress
International Nuclear Information System (INIS)
Ovrut, B.A.; Steinhardt, P.J.
1986-01-01
The new inflationary universe scenario is, in principle, a simple and powerful approach to resolving a large number of fundamental cosmological problems. However, in order for the scenario to be considered a complete theory, one critical question remains to be answered: What is the physics responsible for the phase transition that triggers the exponential expansion (inflation) of the universe? One possibility that the authors and several other groups have been pursuing is that the physics responsible for the phase transition involves (local) supersymmetry. The goal of this paper is to review the present status of ''Supersymmetric Inflation'', particularly emphasizing some very exciting results that they recently obtained
International Nuclear Information System (INIS)
Brandenberger, R.H.
1986-01-01
Cosmological phase transitions are examined using a new approach based on the dynamical analysis of the equations of motion of quantum fields rather than on static effective potential considerations. In many models the universe enters a period of exponential expansion required for an inflationary cosmology. Analytical methods show that this will be the case if the interaction rate due to quantum field nonlinearities is small compared to the expansion rate of the universe. They derive a heuristic criterion for the maximal value of the coupling constant for which they expect inflation. The prediction is in good agreement with numerical results
International Nuclear Information System (INIS)
Albrecht, A.; Brandenberger, R.H.
1985-01-01
We examine cosmological phase transitions using a new approach and argue that there are many models in which the universe enters a period of exponential expansion required for an inflationary cosmology. A sufficient condition is that the interaction rates due to quantum field nonlinearities be sufficiently small compared to the expansion rate of the universe. In Coleman-Weinberg-type models this requires tuning the gauge coupling constant to a low value. In pure scalar field theories, the conditions for inflation are satisfied if the scale of symmetry breaking is of the order of the Planck scale
Producing a scale-invariant spectrum of perturbations in a Hagedorn phase of string cosmology.
Nayeri, Ali; Brandenberger, Robert H; Vafa, Cumrun
2006-07-14
We study the generation of cosmological perturbations during the Hagedorn phase of string gas cosmology. Using tools of string thermodynamics we provide indications that it may be possible to obtain a nearly scale-invariant spectrum of cosmological fluctuations on scales which are of cosmological interest today. In our cosmological scenario, the early Hagedorn phase of string gas cosmology goes over smoothly into the radiation-dominated phase of standard cosmology, without having a period of cosmological inflation.
Higher Curvature Supergravity, Supersymmetry Breaking and Inflation
Ferrara, Sergio
2017-01-01
In these lectures, after a short introduction to cosmology, we discuss the supergravity embedding of higher curvature models of inflation. The supergravity description of such models is presented for the two different formulations of minimal supergravity.
International Nuclear Information System (INIS)
Ellis, J.; Enqvist, K.; Nanopoulos, D.V.; Olive, K.A.; Srednicki, M.
1985-01-01
We present a simple model for primordial inflation in the context of SU(N, 1) no-scale n=1 supergravity. Because the model at zero temperature very closely resembles global supersymmetry, minima with negative cosmological constants do not exist, and it is easy to have a long inflationary epoch while keeping density perturbations of the right magnitude and satisfying other cosmological constraints. We pay specific attention to satisfying the thermal constraint for inflation, i.e. the existence of a high temperature minimum at the origin. (orig.)
Complex Hybrid Inflation and Baryogenesis
Delepine, David; Martinez, Carlos; Urena-Lopez, L. Arturo
2006-01-01
We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U(1) global symmetry associated to the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vev of the waterfall field, which is well constrained by diverse cosmological observations.
Complex Hybrid Inflation and Baryogenesis
International Nuclear Information System (INIS)
Delepine, David; Martinez, Carlos; Urena-Lopez, L. Arturo
2007-01-01
We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U(1) global symmetry associated with the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vacuum expectation value of the waterfall field, which is well constrained by diverse cosmological observations
Complex hybrid inflation and baryogenesis.
Delepine, David; Martínez, Carlos; Ureña-López, L Arturo
2007-04-20
We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U(1) global symmetry associated with the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vacuum expectation value of the waterfall field, which is well constrained by diverse cosmological observations.
International Nuclear Information System (INIS)
Hawking, S.W.
1984-01-01
The subject of these lectures is quantum effects in cosmology. The author deals first with situations in which the gravitational field can be treated as a classical, unquantized background on which the quantum matter fields propagate. This is the case with inflation at the GUT era. Nevertheless the curvature of spacetime can have important effects on the behaviour of the quantum fields and on the development of long-range correlations. He then turns to the question of the quantization of the gravitational field itself. The plan of these lectures is as follows: Euclidean approach to quantum field theory in flat space; the extension of techniques to quantum fields on a curved background with the four-sphere, the Euclidean version of De Sitter space as a particular example; the GUT era; quantization of the gravitational field by Euclidean path integrals; mini superspace model. (Auth.)
An introduction to modern cosmology
Liddle, Andrew
2015-01-01
An Introduction to Modern Cosmology Third Edition is an accessible account of modern cosmological ideas. The Big Bang Cosmology is explored, looking at its observational successes in explaining the expansion of the Universe, the existence and properties of the cosmic microwave background, and the origin of light elements in the universe. Properties of the very early Universe are also covered, including the motivation for a rapid period of expansion known as cosmological inflation. The third edition brings this established undergraduate textbook up-to-date with the rapidly evolving observation
Energy Technology Data Exchange (ETDEWEB)
Ellis, John [Theoretical Particle Physics and Cosmology Group, Department of Physics, King’s College London, Strand, London WC2R 2LS (United Kingdom); Theory Division, CERN, Route de Meyrin 385, 1217 Meyrin (Switzerland); Gonzalo, Tomás E.; Harz, Julia; Huang, Wei-Chih [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2015-03-23
We analyse the prospects for constructing hybrid models of inflation that provide a dynamical realisation of the apparent closeness between the supersymmetric GUT scale and the possible scale of cosmological inflation. In the first place, we consider models based on the flipped SU(5)×U(1) gauge group, which has no magnetic monopoles. In one model, the inflaton is identified with a sneutrino field, and in the other model it is a gauge singlet. In both cases we find regions of the model parameter spaces that are compatible with the experimental magnitudes of the scalar perturbations, A{sub s}, and the tilt in the scalar perturbation spectrum, n{sub s}, as well as with an indicative upper limit on the tensor-to-scalar perturbation ratio, r. We also discuss embeddings of these models into SO(10), which is broken at a higher scale so that its monopoles are inflated away.
Energy Technology Data Exchange (ETDEWEB)
Ellis, John [Theoretical Particle Physics and Cosmology Group, Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Gonzalo, Tomás E.; Harz, Julia; Huang, Wei-Chih, E-mail: john.ellis@cern.ch, E-mail: tomas.gonzalo.11@ucl.ac.uk, E-mail: j.harz@ucl.ac.uk, E-mail: wei-chih.huang@ucl.ac.uk [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2015-03-01
We analyse the prospects for constructing hybrid models of inflation that provide a dynamical realisation of the apparent closeness between the supersymmetric GUT scale and the possible scale of cosmological inflation. In the first place, we consider models based on the flipped SU(5)×U(1) gauge group, which has no magnetic monopoles. In one model, the inflaton is identified with a sneutrino field, and in the other model it is a gauge singlet. In both cases we find regions of the model parameter spaces that are compatible with the experimental magnitudes of the scalar perturbations, A{sub s}, and the tilt in the scalar perturbation spectrum, n{sub s}, as well as with an indicative upper limit on the tensor-to-scalar perturbation ratio, r. We also discuss embeddings of these models into SO(10), which is broken at a higher scale so that its monopoles are inflated away.
Ellis, John; Harz, Julia; Huang, Wei-Chih
2015-01-01
We analyse the prospects for constructing hybrid models of inflation that provide a dynamical realisation of the apparent closeness between the supersymmetric GUT scale and the possible scale of cosmological inflation. In the first place, we consider models based on the flipped SU(5)$\\times$U(1) gauge group, which has no magnetic monopoles. In one model, the inflaton is identified with a sneutrino field, and in the other model it is a gauge singlet. In both cases we find regions of the model parameter spaces that are compatible with the experimental magnitudes of the scalar perturbations, $A_s$, and the tilt in the scalar perturbation spectrum, $n_s$, as well as with an indicative upper limit on the tensor-to-scalar perturbation ratio, $r$. We also discuss embeddings of these models into SO(10), which is broken at a higher scale so that its monopoles are inflated away.
Transdimensional physics and inflation
International Nuclear Information System (INIS)
Giudice, Gian F.; Kolb, Edward W.; Lesgourgues, Julien; Riotto, Antonio
2002-01-01
Within the framework of a five-dimensional brane world with a stabilized radion, we compute the cosmological perturbations generated during inflation and show that the perturbations are a powerful tool to probe the physics of extra dimensions. While we find that the power spectrum of scalar perturbations is unchanged, we show that the existence of the fifth dimension is imprinted on the spectrum of gravitational waves generated during inflation. In particular, we find that the tensor perturbations receive a correction proportional to (HR) 2 , where H is the Hubble expansion rate during inflation and R is the size of the extra dimension. We also generalize our findings to the case of several extra dimensions as well as to warped geometries
Transdimensional physics and inflation
Giudice, Gian Francesco; Lesgourgues, Julien; Riotto, Antonio; Giudice, Gian F.; Kolb, Edward W.; Lesgourgues, Julien; Riotto, Antonio
2002-01-01
Within the framework of a five-dimensional brane world with a stabilized radion, we compute the cosmological perturbations generated during inflation and show that the perturbations are a powerful tool to probe the physics of extra dimensions. While we find that the power spectrum of scalar perturbations is unchanged, we show that the existence of the fifth dimension is imprinted on the spectrum of gravitational waves generated during inflation. In particular, we find that the tensor perturbations receive a correction proportional to (HR)^2, where H is the Hubble expansion rate during inflation and R is the size of the extra dimension. We also generalize our findings to the case of several extra dimensions as well as to warped geometries.
Chuss, David
2010-01-01
The Cosmic Microwave Background (CMB) has provided a wealth of information about the history and physics of the early Universe. Much progress has been made on uncovering the emerging Standard Model of Cosmology by such experiments as COBE and WMAP, and ESA's Planck Surveyor will likely increase our knowledge even more. Despite the success of this model, mysteries remain. Currently understood physics does not offer a compelling explanation for the homogeneity, flatness, and the origin of structure in the Universe. Cosmic Inflation, a brief epoch of exponential expansion, has been posted to explain these observations. If inflation is a reality, it is expected to produce a background spectrum of gravitational waves that will leave a small polarized imprint on the CMB. Discovery of this signal would give the first direct evidence for inflation and provide a window into physics at scales beyond those accessible to terrestrial particle accelerators. I will briefly review aspects of the Standard Model of Cosmology and discuss our current efforts to design and deploy experiments to measure the polarization of the CMB with the precision required to test inflation.
Bianchi models and new inflation
International Nuclear Information System (INIS)
Turner, M.S.; Widrow, L.
1986-03-01
The promise of the inflationary Universe scenario is to free the present state of the Universe from extreme dependence on initial data. Paradoxically, inflation is usually analyzed in the context of the homogeneous and isotropic Robertson-Walker (RW) cosmological models. We show that all but a small subset of the homogeneous models (the Bianchi models) undergo inflation. Any initial anisotropy is so strongly damped that if sufficient inflation occurs to solve the flatness/horizon problems the Universe today would still be very isotropic. Some of the Bianchi models will eventually (in the exponentially distant future) become very anisotropic again. 15 refs
International Nuclear Information System (INIS)
Turner, Michael S.
1999-01-01
For two decades the hot big-bang model as been referred to as the standard cosmology - and for good reason. For just as long cosmologists have known that there are fundamental questions that are not answered by the standard cosmology and point to a grander theory. The best candidate for that grander theory is inflation + cold dark matter. It holds that the Universe is flat, that slowly moving elementary particles left over from the earliest moments provide the cosmic infrastructure, and that the primeval density inhomogeneities that seed all the structure arose from quantum fluctuations. There is now prima facie evidence that supports two basic tenets of this paradigm. An avalanche of high-quality cosmological observations will soon make this case stronger or will break it. Key questions remain to be answered; foremost among them are: identification and detection of the cold dark matter particles and elucidation of the dark-energy component. These are exciting times in cosmology!
Local Operators in the Eternal Black Hole.
Papadodimas, Kyriakos; Raju, Suvrat
2015-11-20
In the AdS/CFT correspondence, states obtained by Hamiltonian evolution of the thermofield doubled state are also dual to an eternal black-hole geometry, which is glued to the boundary with a time shift generated by a large diffeomorphism. We describe gauge-invariant relational observables that probe the black hole interior in these states and constrain their properties using effective field theory. By adapting recent versions of the information paradox we show that these observables are necessarily described by state-dependent bulk-boundary maps, which we construct explicitly.
Primordial inflation and the monopole problem
International Nuclear Information System (INIS)
Olive, K.A.; Seckel, D.
1984-01-01
This chapter discusses the cosmological abundance of magnetic monopoles in locally supersymmetry grand unified theories (GUTs) and primordial inflation. It is shown how the magnetic monopole problem can be solved in variants of broken N=1 supergravity primordial inflation. The monopole problem and its solution in inflationary models is reviewed. It is demonstrated that the monopole problem can be solved by coupling primordial inflation to supersymmetric SU(5) breaking
Davis Meeting on Cosmic Inflation
Kaloper, N; Knox, L; Cosmic Inflation
2003-01-01
The Davis Meeting on Cosmic Inflation marked an exciting milestone on the road to precision cosmology. This is the index page for the proceedings of the conference. Individual proceedings contributions, when they appear on this archive, are linked from this page.
International Nuclear Information System (INIS)
Kehagias, A.; Riotto, A.
2016-01-01
Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformations which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to scalar, vector and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.
Energy Technology Data Exchange (ETDEWEB)
Kehagias, A. [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece); Riotto, A. [Department of Theoretical Physics,24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland); Center for Astroparticle Physics (CAP),24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland)
2016-05-25
Symmetries play an interesting role in cosmology. They are useful in characterizing the cosmological perturbations generated during inflation and lead to consistency relations involving the soft limit of the statistical correlators of large-scale structure dark matter and galaxies overdensities. On the other hand, in observational cosmology the carriers of the information about these large-scale statistical distributions are light rays traveling on null geodesics. Motivated by this simple consideration, we study the structure of null infinity and the associated BMS symmetry in a cosmological setting. For decelerating Friedmann-Robertson-Walker backgrounds, for which future null infinity exists, we find that the BMS transformations which leaves the asymptotic metric invariant to leading order. Contrary to the asymptotic flat case, the BMS transformations in cosmology generate Goldstone modes corresponding to scalar, vector and tensor degrees of freedom which may exist at null infinity and perturb the asymptotic data. Therefore, BMS transformations generate physically inequivalent vacua as they populate the universe at null infinity with these physical degrees of freedom. We also discuss the gravitational memory effect when cosmological expansion is taken into account. In this case, there are extra contribution to the gravitational memory due to the tail of the retarded Green functions which are supported not only on the light-cone, but also in its interior. The gravitational memory effect can be understood also from an asymptotic point of view as a transition among cosmological BMS-related vacua.
CERN. Geneva
2000-01-01
Most of the puzzles with standard big bang cosmology can be avoided if the big bang is NOT identified with the beginning of time. The short-distance cutoff and duality symmetries of superstring theory suggest a new (so-called pre-big bang) cosmology in which the birth of our Universe is the result of a long classical evolution characterized by a gravitational instability. I will motivate and describe this heretical scenario and compare its phenomenological implications with those of ortodox (post-big bang) inflation.
Difficulties with inflationary cosmology
International Nuclear Information System (INIS)
Penrose, R.
1989-01-01
According to the author, the idea of inflationary cosmology is an ingenious attempt to solve some of the major puzzles of cosmology, most notably the flatness problem, the homogeneity (horizon) problem, and the monopole problem. The homogeneity problem, in particular, is intimately connected with a largely unappreciated, but profound puzzle presented by the second law of thermodynamics. The author argues that the mechanism of inflation does not, by itself, come to terms with this and consequently, comes nowhere close to providing an understanding of the large-scale homogeneity of the universe
Benoit-Lévy, Aurélien; Chardin, Gabriel
2014-05-01
We study an unconventional cosmology, in which we investigate the consequences that antigravity would pose to cosmology. We present the main characteristics of the Dirac-Milne Universe, a cosmological model where antimatter has a negative active gravitational mass. In this non-standard Universe, separate domains of matter and antimatter coexist at our epoch without annihilation, separated by a gravitationally induced depletion zone. We show that this cosmology does not require a priori the Dark Matter and Dark Energy components of the standard model of cosmology. Additionally, inflation becomes an unnecessary ingredient. Investigating this model, we show that the classical cosmological tests such as primordial nucleosynthesis, Type Ia supernovæ and Cosmic Microwave Background are surprisingly concordant.
Cosmic curvature from de Sitter equilibrium cosmology.
Albrecht, Andreas
2011-10-07
I show that the de Sitter equilibrium cosmology generically predicts observable levels of curvature in the Universe today. The predicted value of the curvature, Ω(k), depends only on the ratio of the density of nonrelativistic matter to cosmological constant density ρ(m)(0)/ρ(Λ) and the value of the curvature from the initial bubble that starts the inflation, Ω(k)(B). The result is independent of the scale of inflation, the shape of the potential during inflation, and many other details of the cosmology. Future cosmological measurements of ρ(m)(0)/ρ(Λ) and Ω(k) will open up a window on the very beginning of our Universe and offer an opportunity to support or falsify the de Sitter equilibrium cosmology.
The cosmology/particle physics interface
International Nuclear Information System (INIS)
Olive, K.A.; Schramm, D.N.
1985-01-01
The paper reviews the interface between elementary particle physics and cosmology; and concentrates on inflation and the dark matter problem. Inflationary models of the Universe are examined, including phase transitions and supergravity. The three classes of dark matter problems discussed are: dynamical halos, galaxy formation and clustering, and the Ω=1 of inflation. Possible solutions to the cosmological dark matter problems are considered. (U.K.)
Ultracompact Minihalos as Probes of Inflationary Cosmology.
Aslanyan, Grigor; Price, Layne C; Adams, Jenni; Bringmann, Torsten; Clark, Hamish A; Easther, Richard; Lewis, Geraint F; Scott, Pat
2016-09-30
Cosmological inflation generates primordial density perturbations on all scales, including those far too small to contribute to the cosmic microwave background. At these scales, isolated ultracompact minihalos of dark matter can form well before standard structure formation, if the perturbations have sufficient amplitude. Minihalos affect pulsar timing data and are potentially bright sources of gamma rays. The resulting constraints significantly extend the observable window of inflation in the presence of cold dark matter, coupling two of the key problems in modern cosmology.
International Nuclear Information System (INIS)
Gupta, R.C.; Pradhan, Anirudh; Gupta, Sushant
2012-01-01
Comparatively recent observations on Type-Ia supernovae and low density (Um = 0.3) measurement of matter including dark matter suggest that the present day universe consists mainly of repulsive-gravity type 'exotic matter' with negative-pressure often said 'dark energy' (Ux = O7). But the nature of dark energy is mysterious and its puzzling questions, such as why, how, where and when about the dark energy, are intriguing. In the present paper the authors attempt to answer these questions while making an effort to reveal the genesis of dark energy, and suggest that the cosmological nuclear binding energy liberated during primordial nucleo-synthesis remains trapped dormant for a long time and then is released free which manifests itself as dark energy in the universe. It is also explained why for dark energy the parameter w = -2/3. Noting that w = 1 for stiff matter and w = 1/3 for radiation; w = -2/3 is for dark energy because '- 1' is due to 'deficiency of stiff- nuclear-matter' and that this binding energy is ultimately released as 'radiation' contributing '+ 1/3', making w = -1+ 1/3 = -2/3. When dark energy is released free at Z = 80, w = -2/3. But as on present day at Z = 0 when radiation strength has diminished to ä ? 0, the parameter w = -1 + ä 1/3 = -1. This, thus almost solves the dark- energy mystery of negative pressure and repulsive-gravity. The proposed theory makes several estimates/predictions which agree reasonably well with the astrophysical constraints and observations. Though there are many candidate-theories, the proposed model of this paper presents an entirely new approach (cosmological nuclear energy) as a possible candidate for dark energy. The secret of acceleration of big-universe is hidden in the small-nucleus. (author)
International Nuclear Information System (INIS)
Fliche, H.-H.; Souriau, J.-M.
1978-03-01
On the basis of colorimetric data a composite spectrum of quasars is established from the visible to the Lyman's limit. Its agreement with the spectrum of the quasar 3C273, obtained directly, confirms the homogeneity of these objects. The compatibility of the following hypotheses: negligible evolution of quasars, Friedmann type model of the universe with cosmological constant, is studied by means of two tests: a non-correlation test adopted to the observation conditions and the construction of diagrams (absolute magnitude, volume) using the K-correction deduced from the composite spectrum. This procedure happens to give relatively well-defined values of the parameters; the central values of the density parameter, the reduced curvature and the reduced cosmological constant are: Ω 0 =0.053, k 0 =0.245, lambda-zero=1.19, which correspond to a big bang model, eternally expanding, spatially finite, in which Hubble's parameter H is presently increasing. This model responds well to different cosmological tests: density of matter, diameter of radio sources, age of the universe. Its characteristics suggest various cosmogonic mechanisms, espacially mass formation by growth of empty spherical bubbles [fr
Simple types of anisotropic inflation
International Nuclear Information System (INIS)
Barrow, John D.; Hervik, Sigbjoern
2010-01-01
We display some simple cosmological solutions of gravity theories with quadratic Ricci curvature terms added to the Einstein-Hilbert Lagrangian which exhibit anisotropic inflation. The Hubble expansion rates are constant and unequal in three orthogonal directions. We describe the evolution of the simplest of these homogeneous and anisotropic cosmological models from its natural initial state and evaluate the deviations they will create from statistical isotropy in the fluctuations produced during a period of anisotropic inflation. The anisotropic inflation is not a late-time attractor in these models but the rate of approach to a final isotropic de Sitter state is slow and is conducive to the creation of observable anisotropic statistical effects in the microwave background. The statistical anisotropy would not be scale invariant and the level of statistical anisotropy will grow with scale.
INFLATE: INFlate Landing Apparatus Technology
Koryanov, V. V. K.; Da-Poian, V. D. P.
2018-02-01
Our project, named INFLATE (INFlatable Landing Apparatus Technology), aims at reducing space landing risks and constraints and so optimizing space missions (reducing cost, mass, and risk and in the same time improving performance).
Energy Technology Data Exchange (ETDEWEB)
Dvali, Gia
2003-10-03
We propose a new class of inflationary solutions to the standard cosmological problems (horizon, flatness, monopole,...), based on a modification of old inflation. These models do not require a potential which satisfies the normal inflationary slow-roll conditions. Our universe arises from a single tunneling event as the inflaton leaves the false vacuum. Subsequent dynamics (arising from either the oscillations of the inflaton field or thermal effects) keep a second field trapped in a false minimum, resulting in an evanescent period of inflation (with roughly 50 e-foldings) inside the bubble. This easily allows the bubble to grow sufficiently large to contain our present horizon volume. Reheating is accomplished when the inflaton driving the last stage of inflation rolls down to the true vacuum, and adiabatic density perturbations arise from moduli-dependent Yukawa couplings of the inflaton to matter fields. Our scenario has several robust predictions, including virtual absence of gravity waves, a possible absence of tilt in scalar perturbations, and a higher degree of non-Gaussianity than other models. It also naturally incorporates a solution to the cosmological moduli problem.
Supersymmetric inflationary cosmology
International Nuclear Information System (INIS)
Ruiz-Altaba, M.
1986-06-01
An action is presented, within the framework of supergravity unification, which satisfies all experimental and cosmological constraints. In intermediate scale, around 10 10 - 10 11 GeV, arises from a critical examination of inflation, supersymmetry breaking, fermion masses, proton decay, baryogenesis, and electroweak breaking - including neutrino oscillations and CP violation. Careful consideration is given to some relevant calculations. 86 refs., 10 figs., 5 tabs
Cosmological horizons, quintessence and string theory
International Nuclear Information System (INIS)
Kaloper, Nemanja
2003-01-01
String theory is presently the best candidate for a quantum theory of gravity unified with other forces. It is natural to hope that applications of string theory to cosmology may shed new light on the cosmological conundra, such as singularities, initial conditions, cosmological constant problem and the origin of inflation. Before we can apply string theory to cosmology, there are important conceptual and practical problems which must be addressed. We have reviewed here some of these problems, related to how one defines string theory in a cosmological setting. (author)
No hair theorem for inhomogeneous cosmologies
International Nuclear Information System (INIS)
Jensen, L.G.; Stein-Schabes, J.A.
1986-03-01
We show that under very general conditions any inhomogeneous cosmological model with a positive cosmological constant, that can be described in a synchronous reference system will tend asymptotically in time towards the de Sitter solution. This is shown to be relevant in the context of inflationary models as it makes inflation very weakly dependent on initial conditions. 8 refs
Inflationary cosmology: First 30+ years
Sato, Katsuhiko; Yokoyama, Jun'ichi
2015-08-01
Starting with an account of historical developments in Japan and Russia, we review inflationary cosmology and its basic predictions in a pedagogical manner. We also introduce the generalized G-inflation model, in terms of which all the known single-field inflation models may be described. This formalism allows us to analyze and compare the many inflationary models that have been proposed simultaneously and within a common framework. Finally, current observational constraints on inflation are reviewed, with particular emphasis on the sensitivity of the inferred constraints to the choice of datasets used.
Accelerating cosmologies from exponential potentials
International Nuclear Information System (INIS)
Neupane, Ishwaree P.
2003-11-01
It is learnt that exponential potentials of the form V ∼ exp(-2cφ/M p ) arising from the hyperbolic or flux compactification of higher-dimensional theories are of interest for getting short periods of accelerated cosmological expansions. Using a similar potential but derived for the combined case of hyperbolic-flux compactification, we study a four-dimensional flat (or open) FRW cosmologies and give analytic (and numerical) solutions with exponential behavior of scale factors. We show that, for the M-theory motivated potentials, the cosmic acceleration of the universe can be eternal if the spatial curvature of the 4d spacetime is negative, while the acceleration is only transient for a spatially flat universe. We also briefly discuss about the mass of massive Kaluza-Klein modes and the dynamical stabilization of the compact hyperbolic extra dimensions. (author)
Effect of reheating on predictions following multiple-field inflation
Hotinli, Selim C.; Frazer, Jonathan; Jaffe, Andrew H.; Meyers, Joel; Price, Layne C.; Tarrant, Ewan R. M.
2018-01-01
We study the sensitivity of cosmological observables to the reheating phase following inflation driven by many scalar fields. We describe a method which allows semianalytic treatment of the impact of perturbative reheating on cosmological perturbations using the sudden decay approximation. Focusing on N -quadratic inflation, we show how the scalar spectral index and tensor-to-scalar ratio are affected by the rates at which the scalar fields decay into radiation. We find that for certain choices of decay rates, reheating following multiple-field inflation can have a significant impact on the prediction of cosmological observables.
Energy Technology Data Exchange (ETDEWEB)
Herrera, Ramón, E-mail: ramon.herrera@pucv.cl [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Brasil 2950, Casilla 4059, Valparaíso (Chile)
2017-05-01
A warm inflationary universe in the context of Galileon model or G-model is studied. Under a general formalism we study the inflationary dynamics and the cosmological perturbations considering a coupling of the form G (φ, X )= g (φ) X . As a concrete example, we consider an exponential potential together with the cases in which the dissipation and Galilean coefficients are constants. Also, we study the weak regime given by the condition R <1+3 gH φ-dot , and the strong regime in which 1< R +3 gH φ-dot . Additionally, we obtain constraints on the parameters during the evolution of G-warm inflation, assuming the condition for warm inflation in which the temperature T > H , the conditions or the weak and strong regimes, together with the consistency relation r = r ( n {sub s} ) from Planck data.
Energy Technology Data Exchange (ETDEWEB)
Bachlechner, Thomas C. [Department of Physics, Columbia University,New York, NY 10027 (United States)
2016-12-30
We argue that moduli stabilization generically restricts the evolution following transitions between weakly coupled de Sitter vacua and can induce a strong selection bias towards inflationary cosmologies. The energy density of domain walls between vacua typically destabilizes Kähler moduli and triggers a runaway towards large volume. This decompactification phase can collapse the new de Sitter region unless a minimum amount of inflation occurs after the transition. A stable vacuum transition is guaranteed only if the inflationary expansion generates overlapping past light cones for all observable modes originating from the reheating surface, which leads to an approximately flat and isotropic universe. High scale inflation is vastly favored. Our results point towards a framework for studying parameter fine-tuning and inflationary initial conditions in flux compactifications.
Herrera, Ramón
2017-05-01
A warm inflationary universe in the context of Galileon model or G-model is studied. Under a general formalism we study the inflationary dynamics and the cosmological perturbations considering a coupling of the form G(phi,X)=g(phi) X. As a concrete example, we consider an exponential potential together with the cases in which the dissipation and Galilean coefficients are constants. Also, we study the weak regime given by the condition RR+3gHdot phi. Additionally, we obtain constraints on the parameters during the evolution of G-warm inflation, assuming the condition for warm inflation in which the temperature T>H, the conditions or the weak and strong regimes, together with the consistency relation r=r(ns) from Planck data.
The Primordial Inflation Explorer
Kogut, Alan J.
2012-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10(exp -3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Inflation as de Sitter instability
Energy Technology Data Exchange (ETDEWEB)
Cadoni, Mariano; Franzin, Edgardo [Universita di Cagliari, Cittadella Universitaria, Dipartimento di Fisica, Monserrato (Italy); INFN, Sezione di Cagliari, Monserrato (Italy); Mignemi, Salvatore [INFN, Sezione di Cagliari, Monserrato (Italy); Universita di Cagliari, Dipartimento di Matematica e Informatica, Cagliari (Italy)
2016-09-15
We consider cosmological inflation generated by a scalar field slowly rolling off from a de Sitter maximum of its potential. The models belong to the class of hilltop models and represent the most general model of this kind in which the scalar potential can be written as the sum of two exponentials. The minimally coupled Einstein-scalar gravity theory obtained in this way is the cosmological version of a two-scale generalization of known holographic models, allowing for solitonic solutions interpolating between an AdS spacetime in the infrared and scaling solutions in the ultraviolet. We then investigate cosmological inflation in the slow-roll approximation. Our model reproduces correctly, for a wide range of its parameters, the most recent experimental data for the power spectrum of primordial perturbations. Moreover, it predicts inflation at energy scales of four to five orders of magnitude below the Planck scale. At the onset of inflation, the mass of the tachyonic excitation, i.e. of the inflaton, turns out to be seven to eight orders of magnitude smaller than the Planck mass. (orig.)
Aspects of supersymmetric inflation
International Nuclear Information System (INIS)
Lindblom, P.R.
1987-01-01
A new supersymmetric inflationary model is presented and shown to possess the following features: a successful slow rollover produced by quantum corrections; an acceptable pattern of supersymmetry breaking leading to the correct value of the electroweak scale; and a stable slow rollover transition to a minimum with vanishing cosmological constant. It is demonstrated that there is a class of GUT models which are compatible with an inflationary universe scenario in which: (a) the GUT and inflationary phase transitions are distinct (as in supersymmetric inflation); and (b) an observable number of GUT monopoles are created thermally due to reheating of the GUT sector after inflation. This provides one of the few ways of reconciling an observation of GUT monopoles with inflation. New techniques are developed for constructing inflationary models with multiple inflation fields, such as generalizing the one-dimensional slow rollover constraints and estimating the contribution to δρ/ρ from fluctuations transverse to the path of the slow rollover. A new method for ending the slow rollover portion of the inflationary transition is developed
Inflation from Minkowski space
International Nuclear Information System (INIS)
Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Uttayarat, Patipan
2014-01-01
We propose a class of scalar models that, once coupled to gravity, lead to cosmologies that smoothly and stably connect an inflationary quasi-de Sitter universe to a low, or even zero-curvature, maximally symmetric spacetime in the asymptotic past, strongly violating the null energy condition ( H-dot ≫H"2) at intermediate times. The models are deformations of the conformal galileon lagrangian and are therefore based on symmetries, both exact and approximate, that ensure the quantum robustness of the whole picture. The resulting cosmological backgrounds can be viewed as regularized extensions of the galilean genesis scenario, or, equivalently, as ‘early-time-complete’ realizations of inflation. The late-time inflationary dynamics possesses phenomenologically interesting properties: it can produce a large tensor-to-scalar ratio within the regime of validity of the effective field theory and can lead to sizeable equilateral nongaussianities.
International Nuclear Information System (INIS)
Ellis, John; Mavromatos, Nikolaos; Nanopoulos, Dimitri; Sakharov, Alexander
2004-01-01
We present a specific model for cosmological inflation driven by the Liouville field in a non-critical supersymmetric string framework, in which the departure from criticality is due to open strings stretched between two moving Type-II 5-branes. We use WMAP and other data on fluctuations in the cosmic microwave background to fix the parameters of the model, such as the relative separation and velocity of the 5-branes, respecting also the constraints imposed by data on light propagation from distant gamma-ray bursters. The model also suggests a small, relaxing component in the present vacuum energy that may accommodate the breaking of supersymmetry
International Nuclear Information System (INIS)
Wainwright, J.
1990-01-01
The workshop on mathematical cosmology was devoted to four topics of current interest. This report contains a brief discussion of the historical background of each topic and a concise summary of the content of each talk. The topics were; the observational cosmology program, the cosmological perturbation program, isotropic singularities, and the evolution of Bianchi cosmologies. (author)
Hyperbolic geometry of cosmological attractors
Carrasco, John Joseph M.; Kallosh, Renata; Linde, Andrei; Roest, Diederik
2015-01-01
Cosmological alpha attractors give a natural explanation for the spectral index n(s) of inflation as measured by Planck while predicting a range for the tensor-to-scalar ratio r, consistent with all observations, to be measured more precisely in future B-mode experiments. We highlight the crucial
International Nuclear Information System (INIS)
Raychaudhuri, A.K.
1979-01-01
The subject is covered in chapters, entitled; introduction; Newtonian gravitation and cosmology; general relativity and relativistic cosmology; analysis of observational data; relativistic models not obeying the cosmological principle; microwave radiation background; thermal history of the universe and nucleosynthesis; singularity of cosmological models; gravitational constant as a field variable; cosmological models based on Einstein-Cartan theory; cosmological singularity in two recent theories; fate of perturbations of isotropic universes; formation of galaxies; baryon symmetric cosmology; assorted topics (including extragalactic radio sources; Mach principle). (U.K.)
Inhomogeneous anisotropic cosmology
International Nuclear Information System (INIS)
Kleban, Matthew; Senatore, Leonardo
2016-01-01
In homogeneous and isotropic Friedmann-Robertson-Walker cosmology, the topology of the universe determines its ultimate fate. If the Weak Energy Condition is satisfied, open and flat universes must expand forever, while closed cosmologies can recollapse to a Big Crunch. A similar statement holds for homogeneous but anisotropic (Bianchi) universes. Here, we prove that arbitrarily inhomogeneous and anisotropic cosmologies with “flat” (including toroidal) and “open” (including compact hyperbolic) spatial topology that are initially expanding must continue to expand forever at least in some region at a rate bounded from below by a positive number, despite the presence of arbitrarily large density fluctuations and/or the formation of black holes. Because the set of 3-manifold topologies is countable, a single integer determines the ultimate fate of the universe, and, in a specific sense, most 3-manifolds are “flat” or “open”. Our result has important implications for inflation: if there is a positive cosmological constant (or suitable inflationary potential) and initial conditions for the inflaton, cosmologies with “flat” or “open” topology must expand forever in some region at least as fast as de Sitter space, and are therefore very likely to begin inflationary expansion eventually, regardless of the scale of the inflationary energy or the spectrum and amplitude of initial inhomogeneities and gravitational waves. Our result is also significant for numerical general relativity, which often makes use of periodic (toroidal) boundary conditions.
Fibre inflation and α-attractors
Energy Technology Data Exchange (ETDEWEB)
Kallosh, Renata; Linde, Andrei [Stanford Univ., Stanford, CA (United States). Stanford Inst. for Theoretical Physics and Dept. of Physics; Leiden Univ. (Netherlands). Lorentz Inst. for Theoretical Physics; Roest, Diederik [Groningen Univ. (Netherlands). Van Swinderen Inst. for Particle Physics and Gravity; Westphal, Alexander [DESY, Hamburg (Germany). Theory Group; Yamada, Yusuke [Stanford Univ., Stanford, CA (United States). Stanford Inst. for Theoretical Physics and Dept. of Physics
2017-07-15
Fibre inflation is a specific string theory construction based on the Large Volume Scenario that produces an inflationary plateau. We outline its relation to α-attractor models for inflation, with the cosmological sector originating from certain string theory corrections leading to α=2 and α=1/2. Above a certain field range, the steepening effect of higher-order corrections leads first to the breakdown of single-field slow-roll and after that to the onset of 2-field dynamics: the overall volume of the extra dimensions starts to participate in the effective dynamics. Finally, we propose effective supergravity models of fibre inflation based on an D3 uplift term with a nilpotent superfield. Specific moduli dependent D3 induced geometries lead to cosmological fibre models but have in addition a de Sitter minimum exit. These supergravity models motivated by fibre inflation are relatively simple, stabilize the axions and disentangle the Hubble parameter from supersymmetry breaking.
Inflation and Inflation Uncertainty in Turkey
dogru, bulent
2014-01-01
Abstract: In this study, the relationship between inflation and inflation uncertainty is analyzed using Granger causality tests with annual inflation series covering the time period 1923 to 2012 for Turkish Economy. Inflation uncertainty is measured by Exponential Generalized Autoregressive Conditional Heteroskedastic model. Econometric findings suggest that although in long run the Friedman's hypothesis that high inflation increases inflation ...
Pre - big bang inflation requires fine tuning
Energy Technology Data Exchange (ETDEWEB)
Turner, Michael S. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Weinberg, Erick J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
1997-10-01
The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness and horizon problems are not solved. Hence, a fine-tuning of initial conditions is required to obtain enough inflation to solve the cosmological problems.
Eternal Rome: Guardian of the Heavenly Gates
Latura, G.
2016-01-01
The power of the Roman Empire did not come solely by way of brutal force. A spiritual vision inherited from the Greeks inspired the Romans—an ascent through the classical Planets to the intersections with the Milky Way, where stood the gates of heaven. This vision stretches back, through Macrobius and Cicero, to Plato's Republic and Timaeus. The Eternal City, capital of the Empire for four centuries, claimed control over the celestial portals, a tradition that is traced on Roman coins and medals over thousands of years. Julius Caesar borrowed enormous sums to campaign for the office of Pontifex Maximus—high priest of Rome—spending a fortune on “bread and circuses” to secure the support of the masses. Consolidating power at every turn, Caesar as dictator-for-life became absolute master of Rome, the city that, according to its coins, ruled the cosmos. Though his mortal frame fell to the knives of the senators, Caesar's soul was seen ascending to heaven as a comet. Thus was born the myth of Divvs Ivlivs—the divine avatar of the Roman Empire, whose name would become synonymous with the title of emperor over millennia (German Kaiser, Hungarian Csaszar, Russian Tsar, to name a few). Caesar's heir, Octavian, piously waited for Lepidus to die of old age before grabbing the office of Pontifex Maximus for himself, a title that would define the celestial authority of the ruler of Rome until Gratian renounced it four centuries later. Ambrose, bishop of Milan, convinced Gratian that such a pagan title was not fit for a Christian. Once the Roman emperor discarded the title Pontifex Maximus, the bishop of Rome picked it up and placed it above his own head, as can be seen on coins and medals of the Vatican to this day. In Jubilee years, the Pope knocks down the brick wall that has kept closed the Holy Door for a generation, a ceremony that reaffirms Rome's control of the celestial gates.
Finite temperature effects in primordial inflation
Gelmini, G. B.; Nanopoulos, D. V.; Olive, K. A.
1983-11-01
We present a detailed study of a recently proposed model for primordial inflation based on an N=1 locally supersymmetric potential. For a large class of parameters with which all cosmological constraints are satisfied, the temperature corrections can be neglected during the inflation period. At higher temperatures, the minimum is not at the origin, but very close to it. Address after July 1, 1983: Theory Group, Fermilab, PO Box 500, Batavia, IL 60510, USA.
Dynamical Baryogenesis in Complex Hybrid Inflation
International Nuclear Information System (INIS)
Delepine, David; Martinez, Carlos; Urena-Lopez, L. Arturo
2008-01-01
We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U (1) global symmetry associated to the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vev of the waterfall field, which is well constrained by diverse cosmological observations
Texture and inflation in a closed universe
International Nuclear Information System (INIS)
Hacyan, S.; Sarmiento, A.
1993-01-01
We present a cosmological model with a global homogeneous texture and inflation, but without an initial singularity. The Universe starts from an equilibrium configuration in a symmetric vacuum; the dynamic stability of this configuration is studied. We obtain numerical solutions which show that the Universe expands exponentially and the texture field decays in a finite time; this corresponds to a period of inflation followed naturally by a Friedmann expansion
Intermediate Inflation or Late Time Acceleration?
International Nuclear Information System (INIS)
Sanyal, A.K.
2008-01-01
The expansion rate of intermediate inflation lies between the exponential and power law expansion but corresponding accelerated expansion does not start at the onset of cosmological evolution. Present study of intermediate inflation reveals that it admits scaling solution and has got a natural exit form it at a later epoch of cosmic evolution, leading to late time acceleration. The corresponding scalar field responsible for such feature is also found to behave as a tracker field for gravity with canonical kinetic term.
Cosmological phase transitions
International Nuclear Information System (INIS)
Kolb, E.W.
1987-01-01
If the universe stated from conditions of high temperature and density, there should have been a series of phase transitions associated with spontaneous symmetry breaking. The cosmological phase transitions could have observable consequences in the present Universe. Some of the consequences including the formation of topological defects and cosmological inflation are reviewed here. One of the most important tools in building particle physics models is the use of spontaneous symmetry breaking (SSB). The proposal that there are underlying symmetries of nature that are not manifest in the vacuum is a crucial link in the unification of forces. Of particular interest for cosmology is the expectation that are the high temperatures of the big bang symmetries broken today will be restored, and that there are phase transitions to the broken state. The possibility that topological defects will be produced in the transition is the subject of this section. The possibility that the Universe will undergo inflation in a phase transition will be the subject of the next section. Before discussing the creation of topological defects in the phase transition, some general aspects of high-temperature restoration of symmetry and the development of the phase transition will be reviewed. 29 references, 1 figure, 1 table
International Nuclear Information System (INIS)
Amsterdamski, P.
1986-01-01
The standard cosmological model is reviewed and shown not to be self-sufficient in that it requires initial conditions most likely to be supplied by quantum cosmology. The possible approaches to the issue of initial conditions for cosmology are then discussed. In this thesis, the author considers three separate problems related to this issue. First, the possibility of inflation is investigated in detail by analyzing the evolution of metric perturbations and fluctuations in the expectation value of a scalar field prior to a phase transition; finite temperature effects are also included. Since the inhomogeneities were damped well before the onset of a phase transition. It is concluded that an inflation was possible. Next, the effective action of neutrino and photon fields is calculated for homogeneous spacetimes with small anisotropy; it is shown that quantum corrections to the action due to these fields influence the evolution of an early Universe in the Same way as do the analogous correction terms arising from a conformally invariant scalar which has been previously studied. Finally, the question of an early anisotropy is also discussed in a framework of Hartle-Hawking wave function of the Universe. A wave function of a Bianchi IX type Universe is calculated in a semiclassical approximation
International Nuclear Information System (INIS)
Desert, F.-Xavier
2004-01-01
After an introduction comprising some definitions, an historical overview, and a discussion of the paradoxical Universe, this course proposes a presentation of fundamental notions and theories, i.e. the restrained relativity and the universal gravitation. The next part addresses the general relativity with the following notions: space-time metrics and principle of generalised covariance, basics of tensor analysis, geodesics, energy-pulse tensor, curvature, Einstein equations, Newtonian limit, Schwarzschild metrics, gravitational waves, gravitational redshift. The next part addresses the standard cosmology with the Friedmann-Robertson-Walker metrics and the Friedmann-Lemaitre equations of the evolution of the Universe. The Universe expansion is then addressed: distances and horizons, Hubble law, determination of the Hubble constant. The next chapter deals with the constituents of the Universe: light matter, baryonic dark matter, black matter, supernovae, Universe acceleration and black energy. Then comes the nuclear evolution of the Universe: thermodynamics of the primordial Universe, the matter-antimatter asymmetry, from quarks to atoms, cosmic abundance, neutron cosmological background, matter-radiation equality, cosmo-chronology or the age of the Universe. The next chapter addresses the cosmological background at 3 K: sky electromagnetic spectrum, measurement of CMB anisotropies, interpretation of anisotropies, growth of perturbations. The last chapter addresses the quantum field theory and inflation: paradoxes of the standard Big Bang, the simple inflation, noticeable consequences
International Nuclear Information System (INIS)
Murphy, P.J.
1987-01-01
The Theory of Inflation, namely, that at some point the entropy content of the universe was greatly increased, has much promise. It may solve the puzzles of homogeneity and the creation of structure. However, no particle physics model has yet been found that can successfully drive inflation. The difficulty in satisfying the constraint that the isotropy of the microwave background places on the effective potential of prospective models is immense. In this work we have codified the requirements of such models in a most general form. We have carefully calculated the amounts of inflation the various problems of the Standard Model need for their solution. We have derived a completely model independent upper bond on the inflationary Hubble parameter. We have developed a general notation with which to probe the possibilities of Multiple Inflation. We have shown that only in very unlikely circumstances will any evidence of an earlier inflation, survive the de Sitter period of its successor. In particular, it is demonstrated that it is most unlikely that two bouts of inflation will yield high amplitudes of density perturbations on small scales and low amplitudes on large. We conclude that, while multiple inflation will be of great theoretical interest, it is unlikely to have any observational impact
Black holes from extended inflation
International Nuclear Information System (INIS)
Hsu, S.D.H.; Lawrence Berkeley Lab., CA
1990-01-01
It is argued that models of extended inflation, in which modified Einstein gravity allows a graceful exit from the false vacuum, lead to copious production of black holes. The critical temperature of the inflationary phase transition must be >10 8 GeV in order to avoid severe cosmological problems in a universe dominated by black holes. We speculate on the possibility that the interiors of false vacuum regions evolve into baby universes. (orig.)
Knotty inflation and the dimensionality of spacetime
Energy Technology Data Exchange (ETDEWEB)
Berera, Arjun [University of Edinburgh, Tait Institute, School of Physics and Astronomy, Edinburgh (United Kingdom); Buniy, Roman V. [Chapman University, Schmid College of Science, Orange, CA (United States); Kephart, Thomas W. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Paes, Heinrich [Technische Universitaet Dortmund, Fakultaet fuer Physik, Dortmund (Germany); Rosa, Joao G. [Departamento de Fisica da Universidade de Aveiro and CIDMA, Aveiro (Portugal)
2017-10-15
We suggest a structure for the vacuum comprised of a network of tightly knotted/linked flux tubes formed in a QCD-like cosmological phase transition and show that such a network can drive cosmological inflation. As the network can be topologically stable only in three space dimensions, this scenario provides a dynamical explanation for the existence of exactly three large spatial dimensions in our Universe. (orig.)
Beyond the Standard Model of Cosmology
International Nuclear Information System (INIS)
Ellis, John; Nanopoulos, D. V.
2004-01-01
Recent cosmological observations of unprecented accuracy, by WMAP in particular, have established a 'Standard Model' of cosmology, just as LEP established the Standard Model of particle physics. Both Standard Models raise open questions whose answers are likely to be linked. The most fundamental problems in both particle physics and cosmology will be resolved only within a framework for Quantum Gravity, for which the only game in town is string theory. We discuss novel ways to model cosmological inflation and late acceleration in a non-critical string approach, and discuss possible astrophysical tests
Energy Technology Data Exchange (ETDEWEB)
Burrage, Clare [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Rham, Claudia de [Univ. de Geneve (Switzerland). Dept. de Physique Theorique; Seery, David [Sussex Univ., Brigthon (United Kingdom). Dept. of Physics and Astronomy; Tolley, Andrew J. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Physics
2010-09-15
Galileon inflation is a radiatively stable higher derivative model of inflation. The model is determined by a finite number of relevant operators which are protected by a covariant generalization of the Galileon shift symmetry. We show that the nongaussianity of the primordial density perturbation generated during an epoch of Galileon inflation is a particularly powerful observational probe of these models and that, when the speed of sound is small, f{sub NL} can be larger than the usual result f{sub NL} {proportional_to} C{sup -2}{sub s}. (orig.)
Staggered multi-field inflation
International Nuclear Information System (INIS)
Battefeld, Diana; Battefeld, Thorsten; Davis, Anne-Christine
2008-01-01
We investigate multi-field inflationary scenarios with fields that drop out of the model in a staggered fashion. This feature is natural in certain multi-field inflationary setups within string theory; for instance, it can manifest itself when fields are related to tachyons that condense, or inter-brane distances that become meaningless when branes annihilate. Considering a separable potential, and promoting the number of fields to a smooth time dependent function, we derive the formalism to deal with these models at the background and perturbed level, providing general expressions for the scalar spectral index and the running. We recover known results of e.g. a dynamically relaxing cosmological constant in the appropriate limits. We further show that isocurvature perturbations are suppressed during inflation, and so perturbations are adiabatic and nearly Gaussian. The resulting setup might be interpreted as a novel type of warm inflation, readily implemented within string theory and without many of the shortcomings associated with warm inflation. To exemplify the applicability of the formalism we consider three concrete models: assisted inflation with exponential potentials as a simple toy model (a graceful exit becomes possible), inflation from multiple tachyons (a constant decay rate of the number of fields and negligible slow roll contributions turns out to be in good agreement with observations) and inflation from multiple M5-branes within M-theory (a narrow stacking of branes yields a consistent scenario)
Inflation from supersymmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Antoniadis, I. [UMR CNRS 7589 Sorbonne Universites, UPMC Paris 6, LPTHE, Paris (France); University of Bern, Albert Einstein Center, Institute for Theoretical Physics, Bern (Switzerland); Chatrabhuti, A.; Isono, H.; Knoops, R. [Chulalongkorn University, Department of Physics, Faculty of Science, Pathumwan, Bangkok (Thailand)
2017-11-15
We explore the possibility that inflation is driven by supersymmetry breaking with the superpartner of the goldstino (sgoldstino) playing the role of the inflaton. Moreover, we impose an R-symmetry that allows one to satisfy easily the slow-roll conditions, avoiding the so-called η-problem, and leads to two different classes of small-field inflation models; they are characterised by an inflationary plateau around the maximum of the scalar potential, where R-symmetry is either restored or spontaneously broken, with the inflaton rolling down to a minimum describing the present phase of our Universe. To avoid the Goldstone boson and be left with a single (real) scalar field (the inflaton), R-symmetry is gauged with the corresponding gauge boson becoming massive. This framework generalises a model studied recently by the present authors, with the inflaton identified by the string dilaton and R-symmetry together with supersymmetry restored at weak coupling, at infinity of the dilaton potential. The presence of the D-term allows a tuning of the vacuum energy at the minimum. The proposed models agree with cosmological observations and predict a tensor-to-scalar ratio of primordial perturbations 10{sup -9}
Gravitational waves from inflation
International Nuclear Information System (INIS)
Guzzetti, M.C.; Bartolo, N.; Liguori, M.; Matarrese, S.
2016-01-01
The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index ηT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.
International Nuclear Information System (INIS)
Brechet, S D; Hobson, M P; Lasenby, A N
2008-01-01
A dynamical analysis of an effective homogeneous and irrotational Weyssenhoff fluid in general relativity is performed using the 1 + 3 covariant approach that enables the dynamics of the fluid to be determined without assuming any particular form for the spacetime metric. The spin contributions to the field equations produce a bounce that averts an initial singularity, provided that the spin density exceeds the rate of shear. At later times, when the spin contribution can be neglected, a Weyssenhoff fluid reduces to a standard cosmological fluid in general relativity. Numerical solutions for the time evolution of the generalized scale factor R(t) in spatially curved models are presented, some of which exhibit eternal oscillatory behaviour without any singularities. In spatially flat models, analytical solutions for particular values of the equation-of-state parameter are derived. Although the scale factor of a Weyssenhoff fluid generically has a positive temporal curvature near a bounce, it requires unreasonable fine tuning of the equation-of-state parameter to produce a sufficiently extended period of inflation to fit the current observational data
International Nuclear Information System (INIS)
Landsberg, P.T.; Evans, D.A.
1977-01-01
The subject is dealt with in chapters, entitled: cosmology -some fundamentals; Newtonian gravitation - some fundamentals; the cosmological differential equation - the particle model and the continuum model; some simple Friedmann models; the classification of the Friedmann models; the steady-state model; universe with pressure; optical effects of the expansion according to various theories of light; optical observations and cosmological models. (U.K.)
Chameleon field dynamics during inflation
Saba, Nasim; Farhoudi, Mehrdad
By studying the chameleon model during inflation, we investigate whether it can be a successful inflationary model, wherein we employ the common typical potential usually used in the literature. Thus, in the context of the slow-roll approximations, we obtain the e-folding number for the model to verify the ability of resolving the problems of standard big bang cosmology. Meanwhile, we apply the constraints on the form of the chosen potential and also on the equation of state parameter coupled to the scalar field. However, the results of the present analysis show that there is not much chance of having the chameleonic inflation. Hence, we suggest that if through some mechanism the chameleon model can be reduced to the standard inflationary model, then it may cover the whole era of the universe from the inflation up to the late time.
Partially massless fields during inflation
Baumann, Daniel; Goon, Garrett; Lee, Hayden; Pimentel, Guilherme L.
2018-04-01
The representation theory of de Sitter space allows for a category of partially massless particles which have no flat space analog, but could have existed during inflation. We study the couplings of these exotic particles to inflationary perturbations and determine the resulting signatures in cosmological correlators. When inflationary perturbations interact through the exchange of these fields, their correlation functions inherit scalings that cannot be mimicked by extra massive fields. We discuss in detail the squeezed limit of the tensor-scalar-scalar bispectrum, and show that certain partially massless fields can violate the tensor consistency relation of single-field inflation. We also consider the collapsed limit of the scalar trispectrum, and find that the exchange of partially massless fields enhances its magnitude, while giving no contribution to the scalar bispectrum. These characteristic signatures provide clean detection channels for partially massless fields during inflation.
Warm Inflation with Nonminimal Derivative Coupling
International Nuclear Information System (INIS)
Rashidi, N.; Nozari, Kourosh; Shoukrani, M.
2014-01-01
We study the effects of the nonminimal derivative coupling on the dissipative dynamics of the warm inflation where the scalar field is nonminimally coupled to gravity via its kinetic term. We present a detailed calculation of the cosmological perturbations in this setup. We use the recent observational data from the joint data set of WMAP9 + BAO + H 0 and also the Planck satellite data to constrain our model parameters for natural and chaotic inflation potentials. We study also the levels of non-Gaussianity in this warm inflation model and we confront the result with recent observational data from the Planck satellite
Eternal and evanescent black holes and accelerating mirror analogs
Good, Michael R. R.; Linder, Eric V.
2018-03-01
The analogy between black hole radiation and accelerating mirror radiation (the dynamical Casimir effect) is particularly strong for mirror trajectories giving rise to a constant thermal flux of particles. We present new ways to achieve such thermal plateaus, and customize their finite, semi-infinite, and eternal presence, corresponding to forming/collapsing, complete-evaporation/remnants, and eternal black holes. We find simple expressions for the energy flux in terms of the mirror rapidity as a function of proper time and null time.
Towards a superstring cosmology
International Nuclear Information System (INIS)
Taylor, J.G.
1987-01-01
If superstring theory is a theory of everything then it must give a satisfactory description of the very early evolution of the universe. Since the very early universe is not directly observable, then by satisfactory it is mean that the later evolution following the earlier (pre-Planck time era) phase leads to agreement with prediction for the various observable phenomena such as (B-bar B), inflation, galaxy structure, the cosmological constant (infimum), etc. Moreover it is to be hoped that the initial singularity of classical general relativistic cosmology is also avoided. It is clear that superstring theory is not yet able to tackle these problems. This paper describes what has been done so far to construct very simplified versions of string theory relevant to the early universe, and discusses the critical questions still to be answered
Issues on generating primordial anisotropies at the end of inflation
Energy Technology Data Exchange (ETDEWEB)
Emami, Razieh; Firouzjahi, Hassan, E-mail: emami@mail.ipm.ir, E-mail: firouz@mail.ipm.ir [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2012-01-01
We revisit the idea of generating primordial anisotropies at the end of inflation in models of inflation with gauge fields. To be specific we consider the charged hybrid inflation model where the waterfall field is charged under a U(1) gauge field so the surface of end of inflation is controlled both by inflaton and the gauge fields. Using δN formalism properly we find that the anisotropies generated at the end of inflation from the gauge field fluctuations are exponentially suppressed on cosmological scales. This is because the gauge field evolves exponentially during inflation while in order to generate appreciable anisotropies at the end of inflation the spectator gauge field has to be frozen. We argue that this is a generic feature, that is, one can not generate observable anisotropies at the end of inflation within an FRW background.
Issues on generating primordial anisotropies at the end of inflation
International Nuclear Information System (INIS)
Emami, Razieh; Firouzjahi, Hassan
2012-01-01
We revisit the idea of generating primordial anisotropies at the end of inflation in models of inflation with gauge fields. To be specific we consider the charged hybrid inflation model where the waterfall field is charged under a U(1) gauge field so the surface of end of inflation is controlled both by inflaton and the gauge fields. Using δN formalism properly we find that the anisotropies generated at the end of inflation from the gauge field fluctuations are exponentially suppressed on cosmological scales. This is because the gauge field evolves exponentially during inflation while in order to generate appreciable anisotropies at the end of inflation the spectator gauge field has to be frozen. We argue that this is a generic feature, that is, one can not generate observable anisotropies at the end of inflation within an FRW background
Observable cosmology and cosmological models
International Nuclear Information System (INIS)
Kardashev, N.S.; Lukash, V.N.; Novikov, I.D.
1987-01-01
Modern state of observation cosmology is briefly discussed. Among other things, a problem, related to Hibble constant and slowdown constant determining is considered. Within ''pancake'' theory hot (neutrino) cosmological model explains well the large-scale structure of the Universe, but does not explain the galaxy formation. A cold cosmological model explains well light object formation, but contradicts data on large-scale structure
Zhang Yuan Zhong
2002-01-01
This book is one of a series in the areas of high-energy physics, cosmology and gravitation published by the Institute of Physics. It includes courses given at a doctoral school on 'Relativistic Cosmology: Theory and Observation' held in Spring 2000 at the Centre for Scientific Culture 'Alessandro Volta', Italy, sponsored by SIGRAV-Societa Italiana di Relativita e Gravitazione (Italian Society of Relativity and Gravitation) and the University of Insubria. This book collects 15 review reports given by a number of outstanding scientists. They touch upon the main aspects of modern cosmology from observational matters to theoretical models, such as cosmological models, the early universe, dark matter and dark energy, modern observational cosmology, cosmic microwave background, gravitational lensing, and numerical simulations in cosmology. In particular, the introduction to the basics of cosmology includes the basic equations, covariant and tetrad descriptions, Friedmann models, observation and horizons, etc. The ...
Energy Technology Data Exchange (ETDEWEB)
Turner, Michael S
1999-03-01
For two decades the hot big-bang model as been referred to as the standard cosmology - and for good reason. For just as long cosmologists have known that there are fundamental questions that are not answered by the standard cosmology and point to a grander theory. The best candidate for that grander theory is inflation + cold dark matter. It holds that the Universe is flat, that slowly moving elementary particles left over from the earliest moments provide the cosmic infrastructure, and that the primeval density inhomogeneities that seed all the structure arose from quantum fluctuations. There is now prima facie evidence that supports two basic tenets of this paradigm. An avalanche of high-quality cosmological observations will soon make this case stronger or will break it. Key questions remain to be answered; foremost among them are: identification and detection of the cold dark matter particles and elucidation of the dark-energy component. These are exciting times in cosmology{exclamation_point}.
Brane-world cosmology and inflation
Indian Academy of Sciences (India)
A Lukas and D Skinner, J. High Energy Phys. 0109, 020 (2001). M C Bento, O Bertolami and A A Sen, Phys. Rev. D67, 063511 (2003). [8] J Garriga and M Sasaki, Phys. Rev. D62, 043523 (2000). [9] K Koyama and J Soda, Phys. Lett. B483, 432 (2000). [10] S Kanno, M Sasaki and J Soda, Prog. Theor. Phys. 109, 357 (2003).
Hagedorn inflation in string gas cosmology
José Nunes da Silva, Tiago
2010-01-01
Durante o século XX, avanços teóricos e experimentais jogaramuma nova luz sobre o estudo da história e evolução do universo, a Cosmologia. A partir dos trabalhos de Edwin Hubble, a cosmologia moderna pôde ser vista como ciência. Mas foi nas últimas décadas, sobretudo, com o desenvolvimento da cosmologia de precisão e devido a uma melhor compreensão da natureza em seu nível mais fundamental, que a Cosmologia despertou maior interesse científico. Uma das fronteiras da área diz re...
International Nuclear Information System (INIS)
Silk, J.; Turner, M.S.
1986-04-01
The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The Ω-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig
Brane cosmology with curvature corrections
International Nuclear Information System (INIS)
Kofinas, Georgios; Maartens, Roy; Papantonopoulos, Eleftherios
2003-01-01
We study the cosmology of the Randall-Sundrum brane-world where the Einstein-Hilbert action is modified by curvature correction terms: a four-dimensional scalar curvature from induced gravity on the brane, and a five-dimensional Gauss-Bonnet curvature term. The combined effect of these curvature corrections to the action removes the infinite-density big bang singularity, although the curvature can still diverge for some parameter values. A radiation brane undergoes accelerated expansion near the minimal scale factor, for a range of parameters. This acceleration is driven by the geometric effects, without an inflation field or negative pressures. At late times, conventional cosmology is recovered. (author)
Hebecker, Arthur; Lust, Dieter; Steinfurt, Stephan; Weigand, Timo
2012-01-01
As a first step towards inflation in genuinely F-theoretic setups, we propose a scenario where the inflaton is the relative position of two 7-branes on holomorphic 4-cycles. Non-supersymmetric gauge flux induces an attractive inter-brane potential. The latter is sufficiently flat in the supergravity regime of large volume moduli. Thus, in contrast to brane-antibrane inflation, fluxbrane inflation does not require warping. We calculate the inflaton potential both in the supergravity approximation and via an open-string one-loop computation on toroidal backgrounds. This leads us to propose a generalisation to genuine Calabi-Yau manifolds. We also comment on competing F-term effects. The end of inflation is marked by the condensation of tachyonic recombination fields between the 7-branes, triggering the formation of a bound state described as a stable extension along the 7-brane divisor. Hence our model fits in the framework of hybrid D-term inflation. We work out the main phenomenological properties of our D-te...
Does Cosmological Scale Expansion Explain the Universe?
Masreliez, C. J.
2009-12-01
The idea of the creation of the world has been central in Western civilization since the earliest recorded history some 6000 years ago and it still prevails, supported by religious dogma. If the creation idea is wrong and the universe is eternal we might wonder why science has not yet revealed this fundamental truth. To understand why, we have to review how the Big Bang theory came to be the dominant cosmological paradigm in spite of many clear indications that the theory might be fundamentally flawed.
17. RMJ Oduor Eternal Damnation, a Reply to Karori Mbugua's ...
African Journals Online (AJOL)
REGINALDS
doctrine of eternal damnation. I avoid using the term “hell”, preferring to use the ... Mbugua goes on to assert that an adequate theory of justice (he probably means. “theory of ..... gratification of lust and hatred and finally parts with the last rag of.
Quantum cosmology of classically constrained gravity
International Nuclear Information System (INIS)
Gabadadze, Gregory; Shang Yanwen
2006-01-01
In [G. Gabadadze, Y. Shang, hep-th/0506040] we discussed a classically constrained model of gravity. This theory contains known solutions of General Relativity (GR), and admits solutions that are absent in GR. Here we study cosmological implications of some of these new solutions. We show that a spatially-flat de Sitter universe can be created from 'nothing'. This universe has boundaries, and its total energy equals to zero. Although the probability to create such a universe is exponentially suppressed, it favors initial conditions suitable for inflation. Then we discuss a finite-energy solution with a nonzero cosmological constant and zero space-time curvature. There is no tunneling suppression to fluctuate into this state. We show that for a positive cosmological constant this state is unstable-it can rapidly transition to a de Sitter universe providing a new unsuppressed channel for inflation. For a negative cosmological constant the space-time flat solutions is stable.
Initial conditions for slow-roll inflation in a random Gaussian landscape
Energy Technology Data Exchange (ETDEWEB)
Masoumi, Ali; Vilenkin, Alexander; Yamada, Masaki, E-mail: ali@cosmos.phy.tufts.edu, E-mail: vilenkin@cosmos.phy.tufts.edu, E-mail: Masaki.Yamada@tufts.edu [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)
2017-07-01
In the landscape perspective, our Universe begins with a quantum tunneling from an eternally-inflating parent vacuum, followed by a period of slow-roll inflation. We investigate the tunneling process and calculate the probability distribution for the initial conditions and for the number of e-folds of slow-roll inflation, modeling the landscape by a small-field one-dimensional random Gaussian potential. We find that such a landscape is fully consistent with observations, but the probability for future detection of spatial curvature is rather low, P ∼ 10{sup −3}.
Current observations with a decaying cosmological constant allow for chaotic cyclic cosmology
International Nuclear Information System (INIS)
Ellis, George F.R.; Platts, Emma; Weltman, Amanda; Sloan, David
2016-01-01
We use the phase plane analysis technique of Madsen and Ellis [1] to consider a universe with a true cosmological constant as well as a cosmological 'constant' that is decaying. Time symmetric dynamics for the inflationary era allows eternally bouncing models to occur. Allowing for scalar field dynamic evolution, we find that if dark energy decays in the future, chaotic cyclic universes exist provided the spatial curvature is positive. This is particularly interesting in light of current observations which do not yet rule out either closed universes or possible evolution of the cosmological constant. We present only a proof of principle, with no definite claim on the physical mechanism required for the present dark energy to decay
Rapid roll inflation with conformal coupling
International Nuclear Information System (INIS)
Kofman, Lev; Mukohyama, Shinji
2008-01-01
Usual inflation is realized with a slow rolling scalar field minimally coupled to gravity. In contrast, we consider dynamics of a scalar with a flat effective potential, conformally coupled to gravity. Surprisingly, it contains an attractor inflationary solution with the rapidly rolling inflaton field. We discuss models with the conformal inflaton with a flat potential (including hybrid inflation). There is no generation of cosmological fluctuations from the conformally coupled inflaton. We consider realizations of modulated (inhomogeneous reheating) or curvaton cosmological fluctuations in these models. We also implement these unusual features for the popular string-theoretic warped inflationary scenario, based on the interacting D3-D3 branes. The original warped brane inflation suffers a large inflaton mass due to conformal coupling to 4-dimensional gravity. Instead of considering this as a problem and trying to cure it with extra engineering, we show that warped inflation with the conformally coupled, rapidly rolling inflaton is yet possible with N=37 efoldings, which requires low-energy scales 1-100 TeV of inflation. Coincidentally, the same warping numerology can be responsible for the hierarchy. It is shown that the scalars associated with angular isometries of the warped geometry of compact manifold (e.g. S 3 of Klebanov-Strassler (KS) geometry) have solutions identical to conformally coupled modes and also cannot be responsible for cosmological fluctuations. We discuss other possibilities
Rapid roll inflation with conformal coupling
Kofman, Lev; Mukohyama, Shinji
2008-02-01
Usual inflation is realized with a slow rolling scalar field minimally coupled to gravity. In contrast, we consider dynamics of a scalar with a flat effective potential, conformally coupled to gravity. Surprisingly, it contains an attractor inflationary solution with the rapidly rolling inflaton field. We discuss models with the conformal inflaton with a flat potential (including hybrid inflation). There is no generation of cosmological fluctuations from the conformally coupled inflaton. We consider realizations of modulated (inhomogeneous reheating) or curvaton cosmological fluctuations in these models. We also implement these unusual features for the popular string-theoretic warped inflationary scenario, based on the interacting D3-D¯3 branes. The original warped brane inflation suffers a large inflaton mass due to conformal coupling to 4-dimensional gravity. Instead of considering this as a problem and trying to cure it with extra engineering, we show that warped inflation with the conformally coupled, rapidly rolling inflaton is yet possible with N=37 efoldings, which requires low-energy scales 1 100 TeV of inflation. Coincidentally, the same warping numerology can be responsible for the hierarchy. It is shown that the scalars associated with angular isometries of the warped geometry of compact manifold (e.g. S3 of Klebanov-Strassler (KS) geometry) have solutions identical to conformally coupled modes and also cannot be responsible for cosmological fluctuations. We discuss other possibilities.
New type of hill-top inflation
Energy Technology Data Exchange (ETDEWEB)
Barvinsky, A.O.; Nesterov, D.V. [Theory Department, Lebedev Physics Institute, Leninsky Prospect 53, Moscow 119991 (Russian Federation); Kamenshchik, A.Yu., E-mail: barvin@td.lpi.ru, E-mail: Alexander.Kamenshchik@bo.infn.it, E-mail: nesterov@td.lpi.ru [Dipartimento di Fisica and INFN, via Irnerio 46, 40126 Bologna (Italy)
2016-01-01
We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on the background of a slowly varying inflaton, which guarantees smallness of slow roll parameters ε and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R{sup 2}-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.
New type of hill-top inflation
Energy Technology Data Exchange (ETDEWEB)
Barvinsky, A.O. [Theory Department, Lebedev Physics Institute,Leninsky Prospect 53, Moscow 119991 (Russian Federation); Department of Physics, Tomsk State University,Lenin Ave. 36, Tomsk 634050 (Russian Federation); Department of Physics and Astronomy, Pacific Institue for Theoretical Physics,University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Kamenshchik, A.Yu. [Dipartimento di Fisica and INFN,via Irnerio 46, 40126 Bologna (Italy); L.D. Landau Institute for Theoretical Physcis,Kosygin str. 2, 119334 Moscow (Russian Federation); Nesterov, D.V. [Theory Department, Lebedev Physics Institute,Leninsky Prospect 53, Moscow 119991 (Russian Federation)
2016-01-20
We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on the background of a slowly varying inflaton, which guarantees smallness of slow roll parameters ϵ and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R{sup 2}-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.
Directory of Open Access Journals (Sweden)
Antipov Valerij Ivanovich
2015-10-01
Full Text Available The article gives a modern interpretation of the Fisher formula, the calculated velocity of circulation of money supply M2 in the interval 1995-2013 and forecast of its changes until 2030 when hypotheses about the rate of inflation and GDP. Points to the fallacy of its direct use to control inflation and money supply. For a more detailed understanding of the inflationary process proposes a new frequency formula and the explanation of the situation with the regulation of prices in the economy.
Energy Technology Data Exchange (ETDEWEB)
Green, Daniel; Horn, Bart; /SLAC /Stanford U., Phys. Dept.; Senatore, Leonardo; /Princeton, Inst. Advanced Study /Harvard U., Phys. Dept. /Harvard-Smithsonian Ctr. Astrophys.; Silverstein, Eva; /SLAC /Stanford U., Phys. Dept.
2009-06-19
We analyze a distinctive mechanism for inflation in which particle production slows down a scalar field on a steep potential, and show how it descends from angular moduli in string compactifications. The analysis of density perturbations - taking into account the integrated effect of the produced particles and their quantum fluctuations - requires somewhat new techniques that we develop. We then determine the conditions for this effect to produce sixty e-foldings of inflation with the correct amplitude of density perturbations at the Gaussian level, and show that these requirements can be straightforwardly satisfied. Finally, we estimate the amplitude of the non-Gaussianity in the power spectrum and find a significant equilateral contribution.
Zvi Bodie
1989-01-01
A contract to insure $1 against inflation is equivalent to a European call option on the consumer price index. When there is no deductible this call option is equivalent to a forward contract on the CPI. Its price is the difference between the prices of a zero coupon real bond and a zero coupon nominal bond, both free of default risk. Provided that the risk-free real rate of interest is positive, the price of such an inflation insurance policy first rises and then falls with time to maturity....
Maleknejad, A.; Sheikh-Jabbari, M. M.; Soda, J.
2013-07-01
The isotropy and homogeneity of the cosmic microwave background (CMB) favors “scalar driven” early Universe inflationary models. However, gauge fields and other non-scalar fields are far more common at all energy scales, in particular at high energies seemingly relevant to inflation models. Hence, in this review we consider the role and consequences, theoretical and observational, that gauge fields can have during the inflationary era. Gauge fields may be turned on in the background during inflation, or may become relevant at the level of cosmic perturbations. There have been two main classes of models with gauge fields in the background, models which show violation of the cosmic no-hair theorem and those which lead to isotropic FLRW cosmology, respecting the cosmic no-hair theorem. Models in which gauge fields are only turned on at the cosmic perturbation level, may source primordial magnetic fields. We also review specific observational features of these models on the CMB and/or the primordial cosmic magnetic fields. Our discussions will be mainly focused on the inflation period, with only a brief discussion on the post inflationary (p)reheating era. Large field models: The initial value of the inflaton field is large, generically super-Planckian, and it rolls slowly down toward the potential minimum at smaller φ values. For instance, chaotic inflation is one of the representative models of this class. The typical potential of large-field models has a monomial form as V(φ)=V0φn. A simple analysis using the dynamical equations reveals that for number of e-folds Ne larger than 60, we require super-Planckian initial field values,5φ0>3M. For these models typically ɛ˜η˜Ne-1. Small field models: Inflaton field is initially small and slowly evolves toward the potential minimum at larger φ values. The small field models are characterized by the following potential V(φ)=V0(1-(), which corresponds to a Taylor expansion about the origin, but more realistic
Attractor behaviour in ELKO cosmology
International Nuclear Information System (INIS)
Basak, Abhishek; Bhatt, Jitesh R.; Shankaranarayanan, S.; Varma, K.V. Prasantha
2013-01-01
We study the dynamics of ELKO in the context of accelerated phase of our universe. To avoid the fine tuning problem associated with the initial conditions, it is required that the dynamical equations lead to an early-time attractor. In the earlier works, it was shown that the dynamical equations containing ELKO fields do not lead to early-time stable fixed points. In this work, using redefinition of variables, we show that ELKO cosmology admits early-time stable fixed points. More interestingly, we show that ELKO cosmology admit two sets of attractor points corresponding to slow and fast-roll inflation. The fast-roll inflation attractor point is unique for ELKO as it is independent of the form of the potential. We also discuss the plausible choice of interaction terms in these two sets of attractor points and constraints on the coupling constant
Inflation and dark energy from three-forms
International Nuclear Information System (INIS)
Koivisto, Tomi S.; Nunes, Nelson J.
2009-01-01
Three-forms can give rise to viable cosmological scenarios of inflation and dark energy with potentially observable signatures distinct from standard single scalar field models. In this study, the background dynamics and linear perturbations of self-interacting three-form cosmology are investigated. The phase space of cosmological solutions possesses (super)-inflating attractors and saddle points, which can describe three-form driven inflation or dark energy. The quantum generation and the classical evolution of perturbations is considered. The scalar and tensor spectra from a three-form inflation and the impact from the presence of a three-form on matter perturbations are computed. Stability properties and equivalence of the model with alternative formulations are discussed.
Herrera, Ramón
2018-03-01
The reconstruction of a warm inflationary universe model from the scalar spectral index n_S(N) and the tensor to scalar ratio r( N) as a function of the number of e-folds N is studied. Under a general formalism we find the effective potential and the dissipative coefficient in terms of the cosmological parameters n_S and r considering the weak and strong dissipative stages under the slow roll approximation. As a specific example, we study the attractors for the index n_S given by nS-1∝ N^{-1} and for the ratio r∝ N^{-2}, in order to reconstruct the model of warm inflation. Here, expressions for the effective potential V(φ ) and the dissipation coefficient Γ (φ ) are obtained.
Ellis, John; Sueiro, Maria
2014-01-01
Inflationary models based on a single scalar field $\\phi$ with a quadratic potential $V = \\frac{1}{2} m^2 \\phi^2$ are disfavoured by the recent Planck constraints on the scalar index, $n_s$, and the tensor-to-scalar ratio for cosmological density perturbations, $r_T$. In this paper we study how such a quadratic inflationary model can be rescued by postulating additional fields with quadratic potentials, such as might occur in sneutrino models, which might serve as either curvatons or supplementary inflatons. Introducing a second scalar field reduces but does not remove the pressure on quadratic inflation, but we find a sample of three-field models that are highly compatible with the Planck data on $n_s$ and $r_T$. We exhibit a specific three-sneutrino example that is also compatible with the data on neutrino mass difference and mixing angles.
A dynamical weak scale from inflation
Energy Technology Data Exchange (ETDEWEB)
You, Tevong, E-mail: tty20@cam.ac.uk [DAMTP, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)
2017-09-01
Dynamical scanning of the Higgs mass by an axion-like particle during inflation may provide a cosmological component to explaining part of the hierarchy problem. We propose a novel interplay of this cosmological relaxation mechanism with inflation, whereby the backreaction of the Higgs vacuum expectation value near the weak scale causes inflation to end. As Hubble drops, the relaxion's dissipative friction increases relative to Hubble and slows it down enough to be trapped by the barriers of its periodic potential. Such a scenario raises the natural cut-off of the theory up to ∼ 10{sup 10} GeV, while maintaining a minimal relaxion sector without having to introduce additional scanning scalars or new physics coincidentally close to the weak scale.
Non-minimally coupled tachyon and inflation
International Nuclear Information System (INIS)
Piao Yunsong; Huang Qingguo; Zhang Xinmin; Zhang Yuanzhong
2003-01-01
In this Letter, we consider a model of tachyon with a non-minimal coupling to gravity and study its cosmological effects. Regarding inflation, we show that only for a specific coupling of tachyon to gravity this model satisfies observations and solves various problems which exist in the single and multi tachyon inflation models. But noting in the string theory the coupling coefficient of tachyon to gravity is of order g s , which in general is very small, we can hardly expect that the non-minimally coupling of tachyon to gravity could provide a reasonable tachyon inflation scenario. Our work may be a meaningful try for the cosmological effect of tachyon non-minimally coupled to gravity
Modified dispersion relations, inflation, and scale invariance
Bianco, Stefano; Friedhoff, Victor Nicolai; Wilson-Ewing, Edward
2018-02-01
For a certain type of modified dispersion relations, the vacuum quantum state for very short wavelength cosmological perturbations is scale-invariant and it has been suggested that this may be the source of the scale-invariance observed in the temperature anisotropies in the cosmic microwave background. We point out that for this scenario to be possible, it is necessary to redshift these short wavelength modes to cosmological scales in such a way that the scale-invariance is not lost. This requires nontrivial background dynamics before the onset of standard radiation-dominated cosmology; we demonstrate that one possible solution is inflation with a sufficiently large Hubble rate, for this slow roll is not necessary. In addition, we also show that if the slow-roll condition is added to inflation with a large Hubble rate, then for any power law modified dispersion relation quantum vacuum fluctuations become nearly scale-invariant when they exit the Hubble radius.
Jones, Bernard J. T.
2017-04-01
Preface; Notation and conventions; Part I. 100 Years of Cosmology: 1. Emerging cosmology; 2. The cosmic expansion; 3. The cosmic microwave background; 4. Recent cosmology; Part II. Newtonian Cosmology: 5. Newtonian cosmology; 6. Dark energy cosmological models; 7. The early universe; 8. The inhomogeneous universe; 9. The inflationary universe; Part III. Relativistic Cosmology: 10. Minkowski space; 11. The energy momentum tensor; 12. General relativity; 13. Space-time geometry and calculus; 14. The Einstein field equations; 15. Solutions of the Einstein equations; 16. The Robertson-Walker solution; 17. Congruences, curvature and Raychaudhuri; 18. Observing and measuring the universe; Part IV. The Physics of Matter and Radiation: 19. Physics of the CMB radiation; 20. Recombination of the primeval plasma; 21. CMB polarisation; 22. CMB anisotropy; Part V. Precision Tools for Precision Cosmology: 23. Likelihood; 24. Frequentist hypothesis testing; 25. Statistical inference: Bayesian; 26. CMB data processing; 27. Parametrising the universe; 28. Precision cosmology; 29. Epilogue; Appendix A. SI, CGS and Planck units; Appendix B. Magnitudes and distances; Appendix C. Representing vectors and tensors; Appendix D. The electromagnetic field; Appendix E. Statistical distributions; Appendix F. Functions on a sphere; Appendix G. Acknowledgements; References; Index.
Topics in inflationary cosmology
International Nuclear Information System (INIS)
Kahn, R.N.
1985-01-01
This thesis examines several topics in the theory of inflationary cosmology. It first proves the existence of Hawking Radiation during the slow-rolling period of a new inflationary universe. It then derives and somewhat extends Bardeen's gauge invariant formalism for calculating the growth of linear gravitational perturbations in a Friedmann-Robertson-Walker cosmological background. This formalism is then applied, first to several new inflationary universe models all of which show a Zel'dovich spectrum of fluctuations, but with amplitude sigma(100 4 ) above observational limits. The general formalism is next applied to models that exhibit primordial inflation. Fluctuations in these models also exhibit a Zel'dovich spectrum here with an acceptable amplitude. Finally the thesis presents the results of new, numerical calculations. A classical, (2 + 1) dimensional computer model is developed that includes a Higgs field (which drives inflation) along with enough auxiliary fields to generate dynamically not only a thermal bath, but also the fluctuations that naturally accompany that bath. The thesis ends with a discussion of future prospects
Cosmological aspects of superstring models
International Nuclear Information System (INIS)
Binetruy, P.
1986-10-01
I consider more specifically the cosmological aspects of supersymmetry breaking in ''superstring models'' (grand unified models which are believed to describe the effective theory obtained by compactification of superstring theories). The most interesting aspects are related to the presence of flat directions in the scalar potential (vacuum degeneracies). These flat directions are discussed both in the hidden sector of these models (do they give rise to inflation) and in the observable sector of quarks, leptons and Higgs particles, in connection with baryogenesis
International Nuclear Information System (INIS)
Steinhardt, P.J.; Accetta, F.S.
1990-01-01
We present a dynamical mechanism for completing inflationary phase transitions via bubble nucleation which can satisfy all known constraints for a wide spectrum of models and parameters. The approach is a generalization of the recent ''extended inflation'' model which corrects a serious flaw. We find an essentially model-independent bubble-size distribution which may be important for large-scale structure
Ho, Chiu Man; Kephart, Thomas W.
2010-01-01
We consider a 4+N dimensional Einstein gravity coupled to a non-linear sigma model. This theory admits a solution in which the N extra dimensions contract exponentially while the ordinary space expand exponentially. Physically, the non-linear sigma fields induce the dynamical compactification of the extra dimensions, which in turn drives inflation. No inflatons are required.
Hybrid inflation in the complex plane
International Nuclear Information System (INIS)
Buchmueller, W.; Domcke, V.; Kamada, K.; Schmitz, K.
2014-04-01
Supersymmetric hybrid inflation is an exquisite framework to connect inflationary cosmology to particle physics at the scale of grand unification. Ending in a phase transition associated with spontaneous symmetry breaking, it can naturally explain the generation of entropy, matter and dark matter. Coupling F-term hybrid inflation to soft supersymmetry breaking distorts the rotational invariance in the complex inflaton plane - an important fact, which has been neglected in all previous studies. Based on the δN formalism, we analyze the cosmological perturbations for the first time in the full two-field model, also taking into account the fast-roll dynamics at and after the end of inflation. As a consequence of the two-field nature of hybrid inflation, the predictions for the primordial fluctuations depend not only on the parameters of the Lagrangian, but are eventually fixed by the choice of the inflationary trajectory. Recognizing hybrid inflation as a two-field model resolves two shortcomings often times attributed to it: The fine-tuning problem of the initial conditions is greatly relaxed and a spectral index in accordance with the PLANCK data can be achieved in a large part of the parameter space without the aid of supergravity corrections. Our analysis can be easily generalized to other (including large-field) scenarios of inflation in which soft supersymmetry breaking transforms an initially single-field model into a multi-field model.
Notari, Alessio
2016-12-22
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
On inflating magnetic fields, and the backreactions thereof
Energy Technology Data Exchange (ETDEWEB)
Urban, Federico R., E-mail: urban@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1 (Canada)
2011-12-01
We investigate in more depth the issue of backreaction in models that attempt at generating cosmological magnetic fields at inflation. By choosing different, physically motivated, parametrisations, we are able to isolate the heart of the problem, namely the existence, alongside the wanted magnetic field, of its electric counterpart, which turns out quite generally to be stronger and redder. We were also able to identify a few more interwoven weak spots (the typically very high scale of inflation, the width of the spectrum of modes processed by inflation, the blindness of the amplification mechanism to the energy scale processed), in a way independent on the specifications of the coupling between inflation and electromagnetism. Despite having stripped down the problem to the core, the obstacles encountered appear insurmountable, thereby posing a challenge to inflation as the incubator of cosmological magnetism.
Loop quantum gravity effects on inflation and the CMB
International Nuclear Information System (INIS)
Tsujikawa, Shinji; Singh, Parampreet; Maartens, Roy
2004-01-01
In loop quantum cosmology, the universe avoids a big bang singularity and undergoes an early and short super-inflation phase. During super-inflation, non-perturbative quantum corrections to the dynamics drive an inflaton field up its potential hill, thus setting the initial conditions for standard inflation. We show that this effect can raise the inflaton high enough to achieve sufficient e-foldings in the standard inflation era. We analyse the cosmological perturbations generated when slow-roll is violated after super-inflation and show that loop quantum effects can in principle leave an indirect signature on the largest scales in the CMB, with some loss of power and running of the spectral index
Sanders, RH; Papantonopoulos, E
2005-01-01
I discuss the classical cosmological tests, i.e., angular size-redshift, flux-redshift, and galaxy number counts, in the light of the cosmology prescribed by the interpretation of the CMB anisotropies. The discussion is somewhat of a primer for physicists, with emphasis upon the possible systematic
International Nuclear Information System (INIS)
Zel'dovich, Ya.B.
1983-01-01
The present state of the art in cosmology is under discussion. The general picture of the Universe evolution is presented, and its main stages are outlined. The prooess of formation of the large scale Universe structure is considered. The possibility of investigation into the ''inflation'' period of the ''very-very early Universe'' from the view point of theoretical physics is sown. It is noted that cosmology will become a complete science only when physics gives an exhaustive answer to all issues raised by cosmology
Aquinas and Contemporary Cosmology: Creation and Beginnings
Carroll, William E.
Discussions in the Middle Ages about creation and the temporal beginning of the world involved sophisticated analyses in theology, metaphysics, and natural philosophy. Mediaeval insights on this subject, especially Thomas Aquinas' defense of the intelligibility of an eternal, created universe, can help to clarify reflections about the philosophical and theological implications of contemporary cosmological theories: from the "singularity" of the Big Bang, to "quantum tunneling from nothing," to multiverse scenarios. Thomas' insights help us to see the value of Georges Lemaître's insistence that his cosmological reflections must be kept separate from an analysis of creation. This essay will look at different senses of "beginning" and examine the claim that creation, in its fundamental meaning, tells us nothing about whether there is a temporal beginning to the universe. Multiverse models, like that recently proposed by Stephen Hawking and Leonard Mlodinow, may challenge certain views of a Grand Designer, but not of a Creator.
International Nuclear Information System (INIS)
Wang Xiaomin; Tegmark, Max; Zaldarriaga, Matias
2002-01-01
We perform a detailed analysis of the latest cosmic microwave background (CMB) measurements (including BOOMERaNG, DASI, Maxima and CBI), both alone and jointly with other cosmological data sets involving, e.g., galaxy clustering and the Lyman Alpha Forest. We first address the question of whether the CMB data are internally consistent once calibration and beam uncertainties are taken into account, performing a series of statistical tests. With a few minor caveats, our answer is yes, and we compress all data into a single set of 24 bandpowers with associated covariance matrix and window functions. We then compute joint constraints on the 11 parameters of the 'standard' adiabatic inflationary cosmological model. Our best fit model passes a series of physical consistency checks and agrees with essentially all currently available cosmological data. In addition to sharp constraints on the cosmic matter budget in good agreement with those of the BOOMERaNG, DASI and Maxima teams, we obtain a heaviest neutrino mass range 0.04-4.2 eV and the sharpest constraints to date on gravity waves which (together with preference for a slight red-tilt) favor 'small-field' inflation models
Inflation, Reionization, and All That: The Primordial Inflation Explorer
Kogut, Alan J.
2012-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10(exp -3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Curvaton paradigm can accommodate multiple low inflation scales
International Nuclear Information System (INIS)
Matsuda, Tomohiro
2004-01-01
Recent arguments show that some curvaton field may generate the cosmological curvature perturbation. As the curvaton is independent of the inflaton field, there is a hope that the fine tunings of inflation models can be cured by the curvaton scenario. More recently, however, Lyth discussed that there is a strong bound for the Hubble parameter during inflation even if one assumes the curvaton scenario. Although the most serious constraint was evaded, the bound seems rather crucial for many models of a low inflation scale. In this paper we try to remove the constraint. We show that the bound is drastically modified if there were multiple stages of inflation. (letter to the editor)
Kehagias, Alex
2017-01-01
We investigate the recently proposed clockwork mechanism delivering light degrees of freedom with suppressed interactions and show, with various examples, that it can be efficiently implemented in inflationary scenarios to generate flat inflaton potentials and small density perturbations without fine-tunings. We also study the clockwork graviton in de Sitter and, interestingly, we find that the corresponding clockwork charge is site-dependent. As a consequence, the amount of tensor modes is generically suppressed with respect to the standard cases where the clockwork set-up is not adopted. This point can be made a virtue in resurrecting models of inflation which were supposed to be ruled out because of the excessive amount of tensor modes from inflation.
Energy Technology Data Exchange (ETDEWEB)
Croon, Djuna; Sanz, Verónica; Setford, Jack [Department of Physics and Astronomy, University of Sussex,Brighton BN1 9QH (United Kingdom)
2015-10-05
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Successful Goldstone Inflation should also be robust against UV corrections, such as from quantum gravity: in the language of the effective field theory this implies that all scales are sub-Planckian. In this paper we present scenarios which realise both requirements by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. We focus on single-field models, for which we notice that both bosonic and fermionic contributions are required and that spinorial fermion representations can generate the right potential shape. We then evaluate the constraints on non-Gaussianity from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB measurements. The fit to CMB data can be connected to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we show how hybrid inflation can be realised in the same context, where both the inflaton and the waterfall fields share a common origin as Goldstones.
Croon, Djuna; Sanz, Verónica; Setford, Jack
2015-10-01
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Successful Goldstone Inflation should also be robust against UV corrections, such as from quantum gravity: in the language of the effective field theory this implies that all scales are sub-Planckian. In this paper we present scenarios which realise both requirements by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. We focus on single-field models, for which we notice that both bosonic and fermionic contributions are required and that spinorial fermion representations can generate the right potential shape. We then evaluate the constraints on non-Gaussianity from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB measurements. The fit to CMB data can be connected to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we show how hybrid inflation can be realised in the same context, where both the inflaton and the waterfall fields share a common origin as Goldstones.
International Nuclear Information System (INIS)
Croon, Djuna; Sanz, Verónica; Setford, Jack
2015-01-01
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Successful Goldstone Inflation should also be robust against UV corrections, such as from quantum gravity: in the language of the effective field theory this implies that all scales are sub-Planckian. In this paper we present scenarios which realise both requirements by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. We focus on single-field models, for which we notice that both bosonic and fermionic contributions are required and that spinorial fermion representations can generate the right potential shape. We then evaluate the constraints on non-Gaussianity from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB measurements. The fit to CMB data can be connected to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we show how hybrid inflation can be realised in the same context, where both the inflaton and the waterfall fields share a common origin as Goldstones.
Solving stochastic inflation for arbitrary potentials
International Nuclear Information System (INIS)
Martin, Jerome; Musso, Marcello
2006-01-01
A perturbative method for solving the Langevin equation of inflationary cosmology in the presence of backreaction is presented. In the Gaussian approximation, the method permits an explicit calculation of the probability distribution of the inflaton field for an arbitrary potential, with or without the volume effects taken into account. The perturbative method is then applied to various concrete models, namely, large field, small field, hybrid, and running mass inflation. New results on the stochastic behavior of the inflaton field in those models are obtained. In particular, it is confirmed that the stochastic effects can be important in new inflation while it is demonstrated they are negligible in (vacuum dominated) hybrid inflation. The case of stochastic running mass inflation is discussed in some details and it is argued that quantum effects blur the distinction between the four classical versions of this model. It is also shown that the self-reproducing regime is likely to be important in this case
Effects of heavy fields on inflationary cosmology
Ortiz, Pablo
2014-01-01
Cosmological inflation is the most successful theory that explains the homogeneity and flatness of the early universe. It also provides a quantum origin for the primordial perturbations that we observe in the Cosmic Microwave Background Radiation (CMB). The simplest models make use of a single
Cosmology with cosmic microwave background anisotropy
Indian Academy of Sciences (India)
Measurements of CMB anisotropy and, more recently, polarization have played a very important role in allowing precise determination of various parameters of the `standard' cosmological model. The expectation of the paradigm of inflation and the generic prediction of the simplest realization of inflationary scenario in the ...
International Nuclear Information System (INIS)
Leibundgut, B.
2005-01-01
Supernovae have developed into a versatile tool for cosmology. Their impact on the cosmological model has been profound and led to the discovery of the accelerated expansion. The current status of the cosmological model as perceived through supernova observations will be presented. Supernovae are currently the only astrophysical objects that can measure the dynamics of the cosmic expansion during the past eight billion years. Ongoing experiments are trying to determine the characteristics of the accelerated expansion and give insight into what might be the physical explanation for the acceleration. (author)
Effects of thermal inflation on small scale density perturbations
Energy Technology Data Exchange (ETDEWEB)
Hong, Sungwook E. [School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Seoul 130-722 (Korea, Republic of); Lee, Hyung-Joo; Lee, Young Jae; Stewart, Ewan D. [Department of Physics, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-338 (Korea, Republic of); Zoe, Heeseung, E-mail: swhong@kias.re.kr, E-mail: ohsk111@kaist.ac.kr, E-mail: noasac@kaist.ac.kr, E-mail: jcap@profstewart.org, E-mail: heezoe@dgist.ac.kr [School of Basic Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno jungang-daero, Daegu 711-873 (Korea, Republic of)
2015-06-01
In cosmological scenarios with thermal inflation, extra eras of moduli matter domination, thermal inflation and flaton matter domination exist between primordial inflation and the radiation domination of Big Bang nucleosynthesis. During these eras, cosmological perturbations on small scales can enter and re-exit the horizon, modifying the power spectrum on those scales. The largest modified scale, k{sub b}, touches the horizon size when the expansion changes from deflation to inflation at the transition from moduli domination to thermal inflation. We analytically calculate the evolution of perturbations from moduli domination through thermal inflation and evaluate the curvature perturbation on the constant radiation density hypersurface at the end of thermal inflation to determine the late time curvature perturbation. Our resulting transfer function suppresses the power spectrum by a factor 0∼ 5 at k >> k{sub b}, with k{sub b} corresponding to anywhere from megaparsec to subparsec scales depending on the parameters of thermal inflation. Thus, thermal inflation might be constrained or detected by small scale observations such as CMB distortions or 21cm hydrogen line observations.
Topics in inflationary cosmologies
International Nuclear Information System (INIS)
Mahajan, S.
1986-04-01
Several aspects of inflationary cosmologies are discussed. An introduction to the standard hot big bang cosmological model is reviewed, and some of the problems associated with it are presented. A short review of the proposals for solving the cosmological conundrums of the big bang model is presented. Old and the new inflationary scenarios are discussed and shown to be unacceptable. Some alternative scenarios especially those using supersymmetry are reviewed briefly. A study is given of inflationary models where the same set of fields that breaks supersymmetry is also responsible for inflation. In these models, the scale of supersymmetry breaking is related to the slope of the potential near the origin and can thus be kept low. It is found that a supersymmetry breaking scale of the order of the weak breaking scale. The cosmology obtained from the simplest of such models is discussed in detail and it is shown that there are no particular problems except a low reheating temperature and a violation of the thermal constraint. A possible solution to the thermal constraint problem is given by introducing a second field, and the role played by this second field in the scenario is discussed. An alternative mechanism for the generation of baryon number within the framework of supergravity inflationary models is studied using the gravitational couplings of the heavy fields with the hidden sector (the sector which breaks supersymmetry). This mechanism is applied to two specific models - one with and one without supersymmetry breaking. The baryon to entropy ratio is found to be dependent on parameters which are model dependent. Finally, the effect of direct coupling between the two sectors on results is related, 88 refs., 6 figs
Physically self-consistent basis for modern cosmology
International Nuclear Information System (INIS)
Khlopov, M.Yu.
2000-01-01
Cosmoparticle physics appeared as a natural result of internal development of cosmology seeking physical grounds for inflation, baryosynthesis, and nonbaryonic dark matter and of particle physics going outside the Standard Model of particle interactions. Its aim is to study the foundations of particle physics and cosmology and their fundamental relationship in the combination of respective indirect cosmological, astrophysical, and physical effects. The ideas on new particles and fields predicted by particle theory and on their cosmological impact are discussed, as well as the methods of cosmoparticle physics to probe these ideas, are considered with special analysis of physical mechanisms for inflation, baryosynthesis, and nonbaryonic dark matter. These mechanisms are shown to reflect the main principle of modern cosmology, putting, instead of formal parameters of cosmological models, physical processes governing the evolution of the big-bang universe. Their realization on the basis of particle theory induces additional model-dependent predictions, accessible to various methods of nonaccelerator particle physics. Probes for such predictions, with the use of astrophysical data, are the aim of cosmoarcheology studying astrophysical effects of new physics. The possibility of finding quantitatively definite relationships between cosmological and laboratory effects on the basis of cosmoparticle approach, as well as of obtaining a unique solution to the problem of physical candidates for inflation, mechanisms of baryogenesis, and multicomponent dark matter, is exemplified in terms of gauge model with broken family symmetry, underlying horizontal unification and possessing quantitatively definite physical grounds for inflation, baryosynthesis, and effectively multicomponent dark-matter scenarios
International Nuclear Information System (INIS)
Berstein, J.
1984-01-01
These lectures offer a self-contained review of the role of neutrinos in cosmology. The first part deals with the question 'What is a neutrino.' and describes in a historical context the theoretical ideas and experimental discoveries related to the different types of neutrinos and their properties. The basic differences between the Dirac neutrino and the Majorana neutrino are pointed out and the evidence for different neutrino 'flavours', neutrino mass, and neutrino oscillations is discussed. The second part summarizes current views on cosmology, particularly as they are affected by recent theoretical and experimental advances in high-energy particle physics. Finally, the close relationship between neutrino physics and cosmology is brought out in more detail, to show how cosmological constraints can limit the various theoretical possibilities for neutrinos and, more particularly, how increasing knowledge of neutrino properties can contribute to our understanding of the origin, history, and future of the Universe. The level is that of the beginning graduate student. (orig.)
International Nuclear Information System (INIS)
Khalatnikov, I.M.; Belinskij, V.A.
1984-01-01
Application of the qualitative theory of dynamic systems to analysis of homogeneous cosmological models is described. Together with the well-known cases, requiring ideal liquid, the properties of cosmological evolution of matter with dissipative processes due to viscosity are considered. New cosmological effects occur, when viscosity terms being one and the same order with the rest terms in the equations of gravitation or even exceeding them. In these cases the description of the dissipative process by means of only two viscosity coefficients (volume and shift) may become inapplicable because all the rest decomposition terms of dissipative addition to the energy-momentum in velocity gradient can be large application of equations with hydrodynamic viscosty should be considered as a model of dissipative effects in cosmology
Lesgourgues, Julien; Miele, Gennaro; Pastor, Sergio
2013-01-01
The role that neutrinos have played in the evolution of the Universe is the focus of one of the most fascinating research areas that has stemmed from the interplay between cosmology, astrophysics and particle physics. In this self-contained book, the authors bring together all aspects of the role of neutrinos in cosmology, spanning from leptogenesis to primordial nucleosynthesis, their role in CMB and structure formation, to the problem of their direct detection. The book starts by guiding the reader through aspects of fundamental neutrino physics, such as the standard cosmological model and the statistical mechanics in the expanding Universe, before discussing the history of neutrinos in chronological order from the very early stages until today. This timely book will interest graduate students and researchers in astrophysics, cosmology and particle physics, who work with either a theoretical or experimental focus.
International Nuclear Information System (INIS)
Zeldovich, Y.B.
1983-01-01
This paper fives a general review of modern cosmology. The following subjects are discussed: hot big bang and periodization of the evolution; Hubble expansion; the structure of the universe (pancake theory); baryon asymmetry; inflatory universe. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Zhang Yuanzhong
2002-06-21
This book is one of a series in the areas of high-energy physics, cosmology and gravitation published by the Institute of Physics. It includes courses given at a doctoral school on 'Relativistic Cosmology: Theory and Observation' held in Spring 2000 at the Centre for Scientific Culture 'Alessandro Volta', Italy, sponsored by SIGRAV-Societa Italiana di Relativita e Gravitazione (Italian Society of Relativity and Gravitation) and the University of Insubria. This book collects 15 review reports given by a number of outstanding scientists. They touch upon the main aspects of modern cosmology from observational matters to theoretical models, such as cosmological models, the early universe, dark matter and dark energy, modern observational cosmology, cosmic microwave background, gravitational lensing, and numerical simulations in cosmology. In particular, the introduction to the basics of cosmology includes the basic equations, covariant and tetrad descriptions, Friedmann models, observation and horizons, etc. The chapters on the early universe involve inflationary theories, particle physics in the early universe, and the creation of matter in the universe. The chapters on dark matter (DM) deal with experimental evidence of DM, neutrino oscillations, DM candidates in supersymmetry models and supergravity, structure formation in the universe, dark-matter search with innovative techniques, and dark energy (cosmological constant), etc. The chapters about structure in the universe consist of the basis for structure formation, quantifying large-scale structure, cosmic background fluctuation, galaxy space distribution, and the clustering of galaxies. In the field of modern observational cosmology, galaxy surveys and cluster surveys are given. The chapter on gravitational lensing describes the lens basics and models, galactic microlensing and galaxy clusters as lenses. The last chapter, 'Numerical simulations in cosmology', deals with spatial and
International Nuclear Information System (INIS)
Zeldovich, Ya.
1984-01-01
The knowledge is summed up of contemporary cosmology on the universe and its development resulting from a great number of highly sensitive observations and the application of contemporary physical theories to the entire universe. The questions are assessed of mass density in the universe, the structure and origin of the universe, its baryon asymmetry and the quantum explanation of the origin of the universe. Physical problems are presented which should be resolved for the future development of cosmology. (Ha)
CERN. Geneva
2007-01-01
The understanding of the Universe at the largest and smallest scales traditionally has been the subject of cosmology and particle physics, respectively. Studying the evolution of the Universe connects today's large scales with the tiny scales in the very early Universe and provides the link between the physics of particles and of the cosmos. This series of five lectures aims at a modern and critical presentation of the basic ideas, methods, models and observations in today's particle cosmology.
Primordial anisotropies in gauged hybrid inflation
Akbar Abolhasani, Ali; Emami, Razieh; Firouzjahi, Hassan
2014-05-01
We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations.
Primordial anisotropies in gauged hybrid inflation
International Nuclear Information System (INIS)
Abolhasani, Ali Akbar; Emami, Razieh; Firouzjahi, Hassan
2014-01-01
We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations
Curvaton as dark matter with secondary inflation
Energy Technology Data Exchange (ETDEWEB)
Gong, Jinn-Ouk; Kitajima, Naoya [Asia Pacific Center for Theoretical Physics, Pohang 37673 (Korea, Republic of); Terada, Takahiro, E-mail: jinn-ouk.gong@apctp.org, E-mail: naoya.kitajima@apctp.org, E-mail: terada@kias.re.kr [Korea Institute for Advanced Study, Seoul 02455 (Korea, Republic of)
2017-03-01
We consider a novel cosmological scenario in which a curvaton is long-lived and plays the role of cold dark matter (CDM) in the presence of a short, secondary inflation. Non-trivial evolution of the large scale cosmological perturbation in the curvaton scenario can affect the duration of the short term inflation, resulting in the inhomogeneous end of inflation. Non-linear parameters of the curvature perturbation are predicted to be f {sub NL} ≈ 5/4 and g {sub NL} ≈ 0. The curvaton abundance can be well diluted by the short-term inflation and accordingly, it does not have to decay into the Standard Model particles. Then the curvaton can account for the present CDM with the isocurvature perturbation being sufficiently suppressed because both the adiabatic and CDM isocurvature perturbations have the same origin. As an explicit example, we consider the thermal inflation scenario and a string axion as a candidate for this curvaton-dark matter. We further discuss possibilities to identify the curvaton-dark matter with the QCD axion.
Probing Inflation via Cosmic Microwave Background Polarimetry
Chuss, David T.
2008-01-01
The Cosmic Microwave Background (CMB) has been a rich source of information about the early Universe. Detailed measurements of its spectrum and spatial distribution have helped solidify the Standard Model of Cosmology. However, many questions still remain. Standard Cosmology does not explain why the early Universe is geometrically flat, expanding, homogenous across the horizon, and riddled with a small anisotropy that provides the seed for structure formation. Inflation has been proposed as a mechanism that naturally solves these problems. In addition to solving these problems, inflation is expected to produce a spectrum of gravitational waves that will create a particular polarization pattern on the CMB. Detection of this polarized signal is a key test of inflation and will give a direct measurement of the energy scale at which inflation takes place. This polarized signature of inflation is expected to be -9 orders of magnitude below the 2.7 K monopole level of the CMB. This measurement will require good control of systematic errors, an array of many detectors having the requisite sensitivity, and a reliable method for removing polarized foregrounds, and nearly complete sky coverage. Ultimately, this measurement is likely to require a space mission. To this effect, technology and mission concept development are currently underway.
The Cosmic Mandala: Celebrating Tibetan Cosmologies
Larsen, Kristine
2008-05-01
The past decade has seen an increased establishment of Tibetan cultural centers in North America and increased public interest in and media coverage of Tibetan culture. As a result, interest has grown in all aspects of this rich tradition. Astronomy has long played an important role in the lives of the Tibetan people, from their unique luni-solar calendar to their tradition of combining what they call "astro-science" and medicine. To this day, nomads in northern Tibet will ask the North Star - the "Stable Star of the North" - to protect a wayward animal for the night in the expectation that the star will aid in the animal's return in the morning. In Tibetan cosmology, our universe is symbolized as a series of parallel disks centered around Mount Meru, with the heavenly bodies orbiting around it. Central to this cosmology is the concept that time and space have no absolute beginning or end (paralleling the concept of eternal human reincarnation), but that at any given time there exist a billionfold impermanent universes, each one involved in its own independent 4-stage cycle of emptiness, becoming, unfolding, and dissolution. Two distinct symbolic cosmology systems, the Abhidharma ("Topics of special knowledge") and Kalachakra ("Wheel of time"), are recognized in Tibetan culture. These cosmologies also differ in their geographical description of Mount Meru and the "continents" as well as the specifics of the 4-stage cosmological cycle. This poster will celebrate the richness of Tibetan "astro-science", including the calendar, star names, traditional cosmological systems, and astronomical artwork, and demonstrate ways that this tradition can be directly utilized to celebrate and teach cultural cosmologies during the IYA.
On the possibility of braneworld quintessential inflation
International Nuclear Information System (INIS)
Dias, Mafalda; Liddle, Andrew R.
2010-01-01
We examine the possibility of achieving quintessential inflation, where the same field serves as both inflaton and quintessence, in the context of a five-dimensional braneworld. Braneworld cosmology provides an appropriate environment as it permits inflation with much steeper potentials than the conventional scenario, which is favorable to a late-time quintessence. We explore a wide space of models, together with contemporary observational data, to determine in which contexts such a picture is possible. We find that such a scenario, although attractive, is in fact impossible to achieve for the potentials studied due to the restrictiveness of current data.
Universality classes for models of inflation
Binetruy, P.; Mabillard, J.; Pieroni, M.; Rosset, C.
2015-01-01
We show that the cosmological evolution of a scalar field in a potential can be obtained from a renormalisation group equation. The slow roll regime of inflation models is understood in this context as the slow evolution close to a fixed point, described by the methods of renormalisation group. This explains in part the universality observed in the predictions of a certain number of inflation models. We illustrate this behavior on a certain number of examples and discuss it in the context of the AdS/CFT correspondence.
Path integral for multi-field inflation
Energy Technology Data Exchange (ETDEWEB)
Gong, Jinn-Ouk [Asia Pacific Center for Theoretical Physics, Pohang 37673 (Korea, Republic of); Department of Physics, Postech, Pohang 37673 (Korea, Republic of); Seo, Min-Seok [Center for Theoretical Physics of the Universe, Institute for Basic Science, 34051 Daejeon (Korea, Republic of); Shiu, Gary [Department of Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States); Department of Physics & Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay (Hong Kong)
2016-07-20
We develop the path integral formalism for studying cosmological perturbations in multi-field inflation, which is particularly well suited to study quantum theories with gauge symmetries such as diffeomorphism invariance. We formulate the gauge fixing conditions based on the Poisson brackets of the constraints, from which we derive two convenient gauges that are appropriate for multi-field inflation. We then adopt the in-in formalism to derive the most general expression for the power spectrum of the curvature perturbation including the corrections from the interactions of the curvature mode with other light degrees of freedom. We also discuss the contributions of the interactions to the bispectrum.
Universality in generalized models of inflation
Energy Technology Data Exchange (ETDEWEB)
Binétruy, P.; Pieroni, M. [AstroParticule et Cosmologie, Université Paris Diderot, CNRS, CEA, Observatoire de Paris, Sorbonne Paris Cité, 10, rue Alice Domon et Léonie Duquet, F-75205 Paris Cedex 13 (France); Mabillard, J., E-mail: pierre.binetruy@apc.univ-paris7.fr, E-mail: joel.mabillard@ed.ac.uk, E-mail: mauro.pieroni@apc.in2p3.fr [School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3JZ (United Kingdom)
2017-03-01
We discuss the cosmological evolution of a scalar field with non standard kinetic term in terms of a Renormalization Group Equation (RGE). In this framework inflation corresponds to the slow evolution in a neighborhood of a fixed point and universality classes for inflationary models naturally arise. Using some examples we show the application of the formalism. The predicted values for the speed of sound c {sub s} {sup 2} and for the amount of non-Gaussianities produced in these models are discussed. In particular, we show that it is possible to introduce models with c {sub s} {sup 2} ≠ 1 that can be in agreement with present cosmological observations.
Gersbach, Hans; Hahn, Volker
2012-01-01
We introduce a new type of incentive contract for central bankers: inflation forecast contracts, which make central bankers’ remunerations contingent on the precision of their inflation forecasts. We show that such contracts enable central bankers to influence inflation expectations more effectively, thus facilitating more successful stabilization of current inflation. Inflation forecast contracts improve the accuracy of inflation forecasts, but have adverse consequences for output. On balanc...
On corpuscular theory of inflation
Energy Technology Data Exchange (ETDEWEB)
Berezhiani, Lasha [Princeton University, Department of Physics, Princeton, NJ (United States)
2017-02-15
In order to go beyond the mean-field approximation, commonly used in the inflationary computations, an identification of the quantum constituents of the inflationary background is made. In particular, the homogeneous scalar field configuration is represented as a Bose-Einstein condensate of the off-shell inflaton degrees of freedom, with mass significantly screened by the gravitational binding energy. The gravitational counterpart of the classical background is considered to be a degenerate state of the off-shell longitudinal gravitons with the frequency of the order of the Hubble scale. As a result, the origin of the density perturbations in the slow-roll regime is identified as an uncertainty in the position of the constituent inflatons. While in the regime of eternal inflation, the scattering of the constituent gravitons becomes the relevant source of the density perturbations. The gravitational waves, on the other hand, originate from the annihilation of the constituent longitudinal gravitons at all energy scales. This results in the quantum depletion of the classical background, leading to the upper bound on the number of e-folds, after which the semi-classical description is expected to break down; this is estimated to be of the order of the entropy of the initial Hubble patch. (orig.)
Lyth, David
2016-01-01
Written by an award-winning cosmologist, this brand new textbook provides advanced undergraduate and graduate students with coverage of the very latest developments in the observational science of cosmology. The book is separated into three parts; part I covers particle physics and general relativity, part II explores an account of the known history of the universe, and part III studies inflation. Full treatment of the origin of structure, scalar fields, the cosmic microwave background and the early universe are provided. Problems are included in the book with solutions provided in a separate solutions manual. More advanced extension material is offered in the Appendix, ensuring the book is fully accessible to students with a wide variety of background experience.
Effective field theory of cosmological perturbations
International Nuclear Information System (INIS)
Piazza, Federico; Vernizzi, Filippo
2013-01-01
The effective field theory of cosmological perturbations stems from considering a cosmological background solution as a state displaying spontaneous breaking of time translations and (adiabatic) perturbations as the related Nambu–Goldstone modes. With this insight, one can systematically develop a theory for the cosmological perturbations during inflation and, with minor modifications, also describe in full generality the gravitational interactions of dark energy, which are relevant for late-time cosmology. The formalism displays a unique set of Lagrangian operators containing an increasing number of cosmological perturbations and derivatives. We give an introductory description of the unitary gauge formalism for theories with broken gauge symmetry—that allows us to write down the most general Lagrangian—and of the Stückelberg ‘trick’—that allows to recover gauge invariance and to make the scalar field explicit. We show how to apply this formalism to gravity and cosmology and we reproduce the detailed analysis of the action in the ADM variables. We also review some basic applications to inflation and dark energy. (paper)
Effective field theory of cosmological perturbations
Piazza, Federico; Vernizzi, Filippo
2013-11-01
The effective field theory of cosmological perturbations stems from considering a cosmological background solution as a state displaying spontaneous breaking of time translations and (adiabatic) perturbations as the related Nambu-Goldstone modes. With this insight, one can systematically develop a theory for the cosmological perturbations during inflation and, with minor modifications, also describe in full generality the gravitational interactions of dark energy, which are relevant for late-time cosmology. The formalism displays a unique set of Lagrangian operators containing an increasing number of cosmological perturbations and derivatives. We give an introductory description of the unitary gauge formalism for theories with broken gauge symmetry—that allows us to write down the most general Lagrangian—and of the Stückelberg ‘trick’—that allows to recover gauge invariance and to make the scalar field explicit. We show how to apply this formalism to gravity and cosmology and we reproduce the detailed analysis of the action in the ADM variables. We also review some basic applications to inflation and dark energy.
Inflation Aversion and the Optimal Inflation Tax
Gaowang Wang; Heng-fu Zou
2011-01-01
The optimal inflation tax is reexamined in the framework of dynamic second best economy populated by individuals with inflation aversion. A simple formula for the optimal inflation rate is derived. Different from the literature, it is shown that if the marginal excess burden of other distorting taxes approaches zero, Friedman's rule for optimum quantity of money is not optimal, and the optimal inflation tax is negative; if the marginal excess burden of other taxes is nonzero, the optimal infl...
International Nuclear Information System (INIS)
Wesson, P.S.
1979-01-01
The Cosmological Principle states: the universe looks the same to all observers regardless of where they are located. To most astronomers today the Cosmological Principle means the universe looks the same to all observers because density of the galaxies is the same in all places. A new Cosmological Principle is proposed. It is called the Dimensional Cosmological Principle. It uses the properties of matter in the universe: density (rho), pressure (p), and mass (m) within some region of space of length (l). The laws of physics require incorporation of constants for gravity (G) and the speed of light (C). After combining the six parameters into dimensionless numbers, the best choices are: 8πGl 2 rho/c 2 , 8πGl 2 rho/c 4 , and 2 Gm/c 2 l (the Schwarzchild factor). The Dimensional Cosmological Principal came about because old ideas conflicted with the rapidly-growing body of observational evidence indicating that galaxies in the universe have a clumpy rather than uniform distribution
ETERNAL COMTEMPORANEITY IN ADVERTISMENTS OF "NAUJOJI ROMUVA" (1931–1940
Directory of Open Access Journals (Sweden)
Gabija Bankauskaitė-Sereikienė
2014-10-01
Full Text Available Advertising appealing to senses is satiated with the dream of immortality. The society striving for an eternal state of mythical youth lives in the reality of theatre and manipulations. On the one hand, advertising offers certain society life models through myth, archetypical symbols. On the other hand, culture of global observation, watching changes life into an illusion and life simulation. The more a person succumbs to abstractedness of life in advertisements, the greater demand for mythical time, eternal moment and harmony arises. Advertising which has categorically prohibited for a society to get older, gives an individual an illusion of eternal contemporaneity through archetypes. Modern man sees himself as a creator of history, hence, he feels great temptation to take part in an imaginary act of creation. The article provides the analysis of archetypac imagery in interwar advertisements on the basis of insights of R. Barthes, G. Debord and M. McLuhan on mythological structures of thinking, advertisements and modern society of a performance as well as thoughts of M. Eliade on repetition of time. For the analysis publication "Naujoji Romuva" (1931-1940 has been chosen. The expression of archetypes has been discussed after they have been categorized into three groups under character and general context of archetypal structures: archetypes of world creation, prototypes of man and woman, and mythical, folklore. Prototypes of man as a hero and woman as having a mystic role to continue the cycle of life, as well as mythical, folklore symbols (mirror, horseshoe, spruce, flower also play the said role. Archetypal imagery is often found in advertisements of cosmetics, chemicals and sealants.
Dark Energy and Inflation from Gravitational Waves
Directory of Open Access Journals (Sweden)
Leonid Marochnik
2017-10-01
Full Text Available In this seven-part paper, we show that gravitational waves (classical and quantum produce the accelerated de Sitter expansion at the start and at the end of the cosmological evolution of the Universe. In these periods, the Universe contains no matter fields but contains classical and quantum metric fluctuations, i.e., it is filled with classical and quantum gravitational waves. In such evolution of the Universe, dominated by gravitational waves, the de Sitter state is the exact solution to the self-consistent equations for classical and quantum gravitational waves and background geometry for the empty space-time with FLRW metric. In both classical and quantum cases, this solution is of the instanton origin since it is obtained in the Euclidean space of imaginary time with the subsequent analytic continuation to real time. The cosmological acceleration from gravitational waves provides a transparent physical explanation to the coincidence, threshold and “old cosmological constant” paradoxes of dark energy avoiding recourse to the anthropic principle. The cosmological acceleration from virtual gravitons at the start of the Universe evolution produces inflation, which is consistent with the observational data on CMB anisotropy. Section 1 is devoted to cosmological acceleration from classical gravitational waves. Section 2 is devoted to the theory of virtual gravitons in the Universe. Section 3 is devoted to cosmological acceleration from virtual gravitons. Section 4 discusses the consistency of the theory with observational data on dark energy and inflation. The discussion of mechanism of acceleration and cosmological scenario are contained in Sections 5 and 6. Appendix contains the theory of stochastic nonlinear gravitational waves of arbitrary wavelength and amplitude in an isotropic Universe.
Sneutrino Inflation with $\\alpha$-attractors
Kallosh, Renata; Roest, Diederik; Wrase, Timm
2016-11-22
Sneutrino inflation employs the fermionic partners of the inflaton and stabilizer field as right-handed neutrinos to realize the seesaw mechanism for light neutrino masses. A crucial ingredient in existing constructions for sneutrino (multi-)natural inflation is an unbroken discrete shift symmetry. We demonstrate that a similar construction applies to $\\alpha$-attractor models. In this case the hyperbolic geometry protects the neutrino Yukawa couplings to the inflaton field, and the masses of leptons and Higgs fields, from blowing up when the inflaton is super-Planckian. We find that the predictions for $n_s$ and $r$ for $\\alpha$-attractor cosmological models, compatible with the current cosmological data, are preserved in the presence of the neutrino sector.
Sanders, Robert H
2016-01-01
The advent of sensitive high-resolution observations of the cosmic microwave background radiation and their successful interpretation in terms of the standard cosmological model has led to great confidence in this model's reality. The prevailing attitude is that we now understand the Universe and need only work out the details. In this book, Sanders traces the development and successes of Lambda-CDM, and argues that this triumphalism may be premature. The model's two major components, dark energy and dark matter, have the character of the pre-twentieth-century luminiferous aether. While there is astronomical evidence for these hypothetical fluids, their enigmatic properties call into question our assumptions of the universality of locally determined physical law. Sanders explains how modified Newtonian dynamics (MOND) is a significant challenge for cold dark matter. Overall, the message is hopeful: the field of cosmology has not become frozen, and there is much fundamental work ahead for tomorrow's cosmologis...
International Nuclear Information System (INIS)
Tkachev, Igor
1993-01-01
When the common ground between particle physics, astrophysics and cosmology started to become a developing area, the Institute for Nuclear Research (INR) of the Russian Academy of Sciences had the foresight in 1981 to institute the Baksan Schools on Particles and Cosmology. This now traditional event, held biannually in the Baksan Valley, has gone on to attract international participation. The site is close to the INR Baksan Neutrino Observatory with its underground and surface installations, including the SAGE gallium solar neutrino detector, the Underground Scintillation Telescope, and the 'Carpet' extensive air shower array. Participation is mainly from experimentalists working in non accelerator particle physics and particle astrophysics. The most recent School, held from April 21 to 28, began with an opening address by INR Director V. A. Matveev. J.Frieman reviewed standard big bang cosmology, emphasizing how the recent COBE results and the observations of large scale galaxy clustering fit into a standard cosmology framework. For inflationary cosmology, he showed how different models may be tested through their predictions for large-scale galactic structure and for cosmic microwave background anisotropy. A.Stebbins presented details of the large scale distribution of galaxies which, combined with velocity information and microwave background anisotropy data, provide strong constraints on theories of the origin of primordial inhomogeneities. Inflation requires, and theories of the large scale structure strongly favour the critical value for the cosmic mass density, while, as D.Seckel explained in his lecture on nucleosynthesis and abundances of the light elements, the baryon contribution to this density has to be tens of times smaller. A general review on the observational evidence for dark matter, dark matter particle candidates and the strategy of dark matter searches was given by I. Tkachev, who stressed the gravitational microlensing MACHO
Inflation, quintessence, and the origin of mass
Wetterich, C.Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, D-69120 Heidelberg, Germany
2015-01-01
In a unified picture both inflation and present dynamical dark energy arise from the same scalar field. The history of the Universe describes a crossover from a scale invariant "past fixed point" where all particles are massless, to a "future fixed point" for which spontaneous breaking of the exact scale symmetry generates the particle masses. The cosmological solution can be extrapolated to the infinite past in physical time - the universe has no beginning. This is seen most easily in a fram...
Quantum creation of topological defects during inflation
International Nuclear Information System (INIS)
Basu, R.; Guth, A.H.; Vilenkin, A.
1991-01-01
Circular loops of string and spherical domain-wall bubbles of radius equal to the horizon can spontaneously nucleate in de Sitter space. These objects are expanded by the subsequent inflation, and by the end of the inflationary era they have a spectrum of sizes extending well beyond the present Hubble length. Monopole-antimonopole pairs with an initial separation equal to the horizon can also be produced. The cosmological implications of these effects are briefly discussed
Inhomogeneous inflation: The initial-value problem
International Nuclear Information System (INIS)
Laguna, P.; Kurki-Suonio, H.; Matzner, R.A.
1991-01-01
We present a spatially three-dimensional study for solving the initial-value problem in general relativity for inhomogeneous cosmologies. We use York's conformal approach to solve the constraint equations of Einstein's field equations for scalar field sources and find the initial data which will be used in the evolution. This work constitutes the first stage in the development of a code to analyze the effects of matter and spacetime inhomogeneities on inflation
A Jacobian elliptic single-field inflation
Energy Technology Data Exchange (ETDEWEB)
Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Gallo, Emanuel [FaMAF, Universidad Nacional de Cordoba, Cordoba (Argentina); Instituto de Fisica Enrique Gaviola (IFEG), CONICET, Cordoba (Argentina)
2015-06-15
In the scenario of single-field inflation, this field is described in terms of Jacobian elliptic functions. This approach provides, when constrained to particular cases, analytic solutions already known in the past, generalizing them to a bigger family of analytical solutions. The emergent cosmology is analyzed using the Hamilton-Jacobi approach and then the main results are contrasted with the recent measurements obtained from the Planck 2015 data. (orig.)
Green, Dan
2016-01-01
This volume makes explicit use of the synergy between cosmology and high energy physics, for example, supersymmetry and dark matter, or nucleosynthesis and the baryon-to-photon ratio. In particular the exciting possible connection between the recently discovered Higgs scalar and the scalar field responsible for inflation is explored.The recent great advances in the accuracy of the basic cosmological parameters is exploited in that no free scale parameters such as h appear, rather the basic calculations are done numerically using all sources of energy density simultaneously. Scripts are provided that allow the reader to calculate exact results for the basic parameters. Throughout MATLAB tools such as symbolic math, numerical solutions, plots and 'movies' of the dynamical evolution of systems are used. The GUI package is also shown as an example of the real time manipulation of parameters which is available to the reader.All the MATLAB scripts are made available to the reader to explore examples of the uses of ...
Particle physics and cosmology
International Nuclear Information System (INIS)
Kolb, E.W.
1986-10-01
This series of lectures is about the role of particle physics in physical processes that occurred in the very early stages of the bug gang. Of particular interest is the role of particle physics in determining the evolution of the early Universe, and the effect of particle physics on the present structure of the Universe. The use of the big bang as a laboratory for placing limits on new particle physics theories will also be discussed. Section 1 reviews the standard cosmology, including primordial nucleosynthesis. Section 2 reviews the decoupling of weakly interacting particles in the early Universe, and discusses neutrino cosmology and the resulting limits that may be placed on the mass and lifetime of massive neutrinos. Section 3 discusses the evolution of the vacuum through phase transitions in the early Universe and the formation of topological defects in the transitions. Section 4 covers recent work on the generation of the baryon asymmetry by baryon-number violating reactions in Grand Unified Theories, and mentions some recent work on baryon number violation effects at the electroweak transition. Section 5 is devoted to theories of cosmic inflation. Finally, Section 6 is a discussion of the role of extra spatial dimensions in the evolution of the early Universe. 78 refs., 32 figs., 6 tabs
Viscous coupled fluids in inflationary cosmology
Energy Technology Data Exchange (ETDEWEB)
Brevik, I., E-mail: iver.h.brevik@ntnu.no [Norwegian University of Science and Technology (Norway); Timoshkin, A. V., E-mail: timoshkinAV@tspu.edu.ru [Tomsk State Pedagogical University (Russian Federation)
2016-04-15
We consider the inflation produced by two coupled fluids in a flat Friedmann–Robertson–Walker universe. Different cosmological models for describing inflation with the use of an inhomogeneous equation of state for the fluid are investigated. The gravitational equations for energy and matter are solved, and analytic representations for the Hubble parameter and the energy density are obtained. Corrections to the energy density for matter inducing the inflation and the coupling to energy are discussed. We analyze the description of inflation induced by nonconstant equation-of-state parameters from fluid viscosity. The correspondence between the spectral index and the tensor-to-scalar ratio recently observed by the Planck satellite is considered.
International Nuclear Information System (INIS)
Dickau, Jonathan J.
2009-01-01
The use of fractals and fractal-like forms to describe or model the universe has had a long and varied history, which begins long before the word fractal was actually coined. Since the introduction of mathematical rigor to the subject of fractals, by Mandelbrot and others, there have been numerous cosmological theories and analyses of astronomical observations which suggest that the universe exhibits fractality or is by nature fractal. In recent years, the term fractal cosmology has come into usage, as a description for those theories and methods of analysis whereby a fractal nature of the cosmos is shown.
Using eternity variables to specify and prove a serializable database interface
Hesselink, Wim H.
Eternity variables are introduced to specify and verify serializability of transactions of a distributed database. Eternity variables are a new kind of auxiliary variables. They do not occur in the implementation but are used in specification and verification. Elsewhere it has been proved that
Bojowald, Martin
2008-01-01
Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time. Supplementary material is available for this article at 10.12942/lrr-2008-4.
Directory of Open Access Journals (Sweden)
Bojowald Martin
2008-07-01
Full Text Available Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.
Directory of Open Access Journals (Sweden)
Bojowald Martin
2005-12-01
Full Text Available Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new kinds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.
How fabulous is Fab 5 cosmology?
International Nuclear Information System (INIS)
Linder, Eric V.
2013-01-01
Extended gravity origins for cosmic acceleration can solve some fine tuning issues and have useful characteristics, but generally have little to say regarding the cosmological constant problem. Fab 5 gravity can be ghost free and stable, have attractor solutions in the past and future, and possess self tuning that solves the original cosmological constant problem. Here we show however it does not possess all these qualities at the same time. We also demonstrate that the self tuning is so powerful that it not only cancels the cosmological constant but also all other energy density, and we derive the scalings of its approach to a renormalized de Sitter cosmology. While this strong cancellation is bad for the late universe, it greatly eases early universe inflation
How fabulous is Fab 5 cosmology?
Energy Technology Data Exchange (ETDEWEB)
Linder, Eric V., E-mail: evlinder@lbl.gov [Berkeley Center for Cosmological Physics and Berkeley Lab, University of California, Berkeley, CA, 94720 (United States)
2013-12-01
Extended gravity origins for cosmic acceleration can solve some fine tuning issues and have useful characteristics, but generally have little to say regarding the cosmological constant problem. Fab 5 gravity can be ghost free and stable, have attractor solutions in the past and future, and possess self tuning that solves the original cosmological constant problem. Here we show however it does not possess all these qualities at the same time. We also demonstrate that the self tuning is so powerful that it not only cancels the cosmological constant but also all other energy density, and we derive the scalings of its approach to a renormalized de Sitter cosmology. While this strong cancellation is bad for the late universe, it greatly eases early universe inflation.
Dissipative Boltzmann-Robertson-Walker cosmologies
International Nuclear Information System (INIS)
Hiscock, W.A.; Salmonson, J.
1991-01-01
The equations governing a flat Robertson-Walker cosmological model containing a dissipative Boltzmann gas are integrated numerically. The bulk viscous stress is modeled using the Eckart and Israel-Stewart theories of dissipative relativistic fluids; the resulting cosmologies are compared and contrasted. The Eckart models are shown to always differ in a significant quantitative way from the Israel-Stewart models. It thus appears inappropriate to use the pathological (nonhyperbolic) Eckart theory for cosmological applications. For large bulk viscosities, both cosmological models approach asymptotic nonequilibrium states; in the Eckart model the total pressure is negative, while in the Israel-Stewart model the total pressure is asymptotically zero. The Eckart model also expands more rapidly than the Israel-Stewart models. These results suggest that ''bulk-viscous'' inflation may be an artifact of using a pathological fluid theory such as the Eckart theory
Detection of gravitational waves from inflation
International Nuclear Information System (INIS)
Kamionkowski, M.; Jaffe, A.H.
2001-01-01
Recent measurements of temperature fluctuations in the cosmic microwave background (CMB) indicate that the Universe is flat and that large-scale structure grew via gravitational infall from primordial adiabatic perturbations. Both of these observations seem to indicate that we are on the right track with inflation. But what is the new physics responsible for inflation? This question can be answered with observations of the polarization of the CMB. Inflation predicts robustly the existence of a stochastic background of cosmological gravitational waves with an amplitude proportional to the square of the energy scale of inflation. This gravitational-wave background induces a unique signature in the polarization of the CMB. If inflation took place at an energy scale much smaller than that of grand unification, then the signal will be too small to be detectable. However, if inflation had something to do with grand unification or Planck-scale physics, then the signal is conceivably detectable in the optimistic case by the Planck satellite, or if not, then by a dedicated post-Planck CMB polarization experiment. Realistic developments in detector technology as well as a proper scan strategy could produce such a post-Planck experiment that would improve on Planck's sensitivity to the gravitational-wave background by several orders of magnitude in a decade timescale. (author)
Born in an infinite universe: A cosmological interpretation of quantum mechanics
International Nuclear Information System (INIS)
Aguirre, Anthony; Tegmark, Max
2011-01-01
We study the quantum measurement problem in the context of an infinite, statistically uniform space, as could be generated by eternal inflation. It has recently been argued that when identical copies of a quantum measurement system exist, the standard projection operators and Born rule method for calculating probabilities must be supplemented by estimates of relative frequencies of observers. We argue that an infinite space actually renders the Born rule redundant, by physically realizing all outcomes of a quantum measurement in different regions, with relative frequencies given by the square of the wave-function amplitudes. Our formal argument hinges on properties of what we term the quantum confusion operator, which projects onto the Hilbert subspace where the Born rule fails, and we comment on its relation to the oft-discussed quantum frequency operator. This analysis unifies the classical and quantum levels of parallel universes that have been discussed in the literature, and has implications for several issues in quantum measurement theory. Replacing the standard hypothetical ensemble of measurements repeated ad infinitum by a concrete decohered spatial collection of experiments carried out in different distant regions of space provides a natural context for a statistical interpretation of quantum mechanics. It also shows how, even for a single measurement, probabilities may be interpreted as relative frequencies in unitary (Everettian) quantum mechanics. We also argue that after discarding a zero-norm part of the wave function, the remainder consists of a superposition of indistinguishable terms, so that arguably 'collapse' of the wave function is irrelevant, and the ''many worlds'' of Everett's interpretation are unified into one. Finally, the analysis suggests a 'cosmological interpretation' of quantum theory in which the wave function describes the actual spatial collection of identical quantum systems, and quantum uncertainty is attributable to the
Energy Technology Data Exchange (ETDEWEB)
Hinterbichler, Kurt [CERCA, Department of Physics, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106 (United States); Joyce, Austin [Center for Theoretical Physics, Department of Physics, Columbia University, New York, NY 10027 (United States); Khoury, Justin, E-mail: kurt.hinterbichler@case.edu, E-mail: austin.joyce@columbia.edu, E-mail: jkhoury@sas.upenn.edu [Center for Particle Cosmology, Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States)
2017-01-01
We investigate the symmetry structure of inflation in 2+1 dimensions. In particular, we show that the asymptotic symmetries of three-dimensional de Sitter space are in one-to-one correspondence with cosmological adiabatic modes for the curvature perturbation. In 2+1 dimensions, the asymptotic symmetry algebra is infinite-dimensional, given by two copies of the Virasoro algebra, and can be traced to the conformal symmetries of the two-dimensional spatial slices of de Sitter. We study the consequences of this infinite-dimensional symmetry for inflationary correlation functions, finding new soft theorems that hold only in 2+1 dimensions. Expanding the correlation functions as a power series in the soft momentum q , these relations constrain the traceless part of the tensorial coefficient at each order in q in terms of a lower-point function. As a check, we verify that the O( q {sup 2}) identity is satisfied by inflationary correlation functions in the limit of small sound speed.
Ellis, G F R
1993-01-01
Many topics were covered in the submitted papers, showing much life in this subject at present. They ranged from conventional calculations in specific cosmological models to provocatively speculative work. Space and time restrictions required selecting from them, for summarisation here; the book of Abstracts should be consulted for a full overview.
International Nuclear Information System (INIS)
Chow, Nathan; Khoury, Justin
2009-01-01
We study the cosmology of a galileon scalar-tensor theory, obtained by covariantizing the decoupling Lagrangian of the Dvali-Gabadadze-Poratti (DGP) model. Despite being local in 3+1 dimensions, the resulting cosmological evolution is remarkably similar to that of the full 4+1-dimensional DGP framework, both for the expansion history and the evolution of density perturbations. As in the DGP model, the covariant galileon theory yields two branches of solutions, depending on the sign of the galileon velocity. Perturbations are stable on one branch and ghostlike on the other. An interesting effect uncovered in our analysis is a cosmological version of the Vainshtein screening mechanism: at early times, the galileon dynamics are dominated by self-interaction terms, resulting in its energy density being suppressed compared to matter or radiation; once the matter density has redshifted sufficiently, the galileon becomes an important component of the energy density and contributes to dark energy. We estimate conservatively that the resulting expansion history is consistent with the observed late-time cosmology, provided that the scale of modification satisfies r c > or approx. 15 Gpc.
Gauss-Bonnet models with cosmological constant and non zero spatial curvature in D = 4
Energy Technology Data Exchange (ETDEWEB)
Armaleo, Juan Manuel [UBA, Departamento de Fisica, Buenos Aires (Argentina); Osorio Morales, Juliana; Santillan, Osvaldo P. [UBA CONICET, Departamento de Matematicas Luis Santalo (IMAS), Buenos Aires (Argentina)
2018-02-15
In the present paper the possibility of eternal universes in Gauss-Bonnet theories of gravity in four dimensions is analysed. It is shown that, for zero spatial curvature and zero cosmological constant, if the coupling is such that 0 < f{sup '}(φ) ≤ c exp((√(8))/(√(10))φ), then there are solutions that are eternal. Similar conclusions are found when a cosmological constant turned on. These conclusions are not generalized for the case when the spatial curvature is present, but we are able to find some general results about the possible nature of the singularities. The presented results correct some dubious arguments in Santillan (JCAP 7:008, 2017), although the same conclusions are reached. On the other hand, these past results are considerably generalized to a wide class of situations which were not considered in Santillan (JCAP 7:008, 2017). (orig.)
International Nuclear Information System (INIS)
Novello, M.
1986-01-01
A resume for an alternative model for the Universe, rather than the Big-Bang, called Eternal Universe, is given. An attempt is made in order to devise solutions for some shortcomings of this model. (L.C.) [pt
Primordial two-component maximally symmetric inflation
Enqvist, K.; Nanopoulos, D. V.; Quirós, M.; Kounnas, C.
1985-12-01
We propose a two-component inflation model, based on maximally symmetric supergravity, where the scales of reheating and the inflation potential at the origin are decoupled. This is possible because of the second-order phase transition from SU(5) to SU(3)×SU(2)×U(1) that takes place when φ≅φcinflation at the global minimum, and leads to a reheating temperature TR≅(1015-1016) GeV. This makes it possible to generate baryon asymmetry in the conventional way without any conflict with experimental data on proton lifetime. The mass of the gravitinos is m3/2≅1012 GeV, thus avoiding the gravitino problem. Monopoles are diluted by residual inflation in the broken phase below the cosmological bounds if φcUSA.
Stochastic approaches to inflation model building
International Nuclear Information System (INIS)
Ramirez, Erandy; Liddle, Andrew R.
2005-01-01
While inflation gives an appealing explanation of observed cosmological data, there are a wide range of different inflation models, providing differing predictions for the initial perturbations. Typically models are motivated either by fundamental physics considerations or by simplicity. An alternative is to generate large numbers of models via a random generation process, such as the flow equations approach. The flow equations approach is known to predict a definite structure to the observational predictions. In this paper, we first demonstrate a more efficient implementation of the flow equations exploiting an analytic solution found by Liddle (2003). We then consider alternative stochastic methods of generating large numbers of inflation models, with the aim of testing whether the structures generated by the flow equations are robust. We find that while typically there remains some concentration of points in the observable plane under the different methods, there is significant variation in the predictions amongst the methods considered
Cosmic Microwave Background Polarization and Inflation
Chuss, David T.
2011-01-01
Measurements of the cosmic microwave background (CMB) offer a means to explore the universe at a very early epoch. Specifically, if the universe went through a brief period of exponential expansion called inflation as current data suggest, gravitational waves from this period would polarize the CMB in a specific pattern. At GSFC, we are currently working towards two experiments that work in concert to measure this polarization pattern in search of evidence for inflation. The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization at frequencies between 40 and 150 GHz from the Atacama Desert in Chile. The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne experiment that will make similar measurements at frequencies between 200 and 600 GHz.
Is inflation from unwinding fluxes IIB?
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Gautason, Fridrik Freyr [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Institut de Physique Théorique, Université Paris Saclay, CEA, CNRS,Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Schillo, Marjorie; Riet, Thomas Van [Instituut voor Theoretische Fysica, K.University Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium)
2017-03-07
In this paper we argue that the mechanism of unwinding inflation is naturally present in warped compactifications of type IIB string theory with local throats. The unwinding of flux is caused by its annihilation against branes. The resulting inflaton potential is linear with periodic modulations. We initiate an analysis of the inflationary dynamics and cosmological observables, which are highly constrained by moduli stabilization. For the simplified model of single-Kähler Calabi-Yau spaces we find that many, though not all of the consistency constraints can be satisfied. Particularly, in this simple model geometric constraints are in tension with obtaining the observed amplitude of the scalar power spectrum. However, we do find 60 efolds of inflation with a trans-Planckian field excursion which offers the hope that slightly more complicated models can lead to a fully consistent explicit construction of large field inflation of this kind.
Fibre inflation and α-attractors
Kallosh, Renata; Linde, Andrei; Roest, Diederik; Westphal, Alexander; Yamada, Yusuke
2018-02-01
Fibre inflation is a specific string theory construction based on the Large Volume Scenario that produces an inflationary plateau. We outline its relation to α-attractor models for inflation, with the cosmological sector originating from certain string theory corrections leading to α = 2 and α = 1/2. Above a certain field range, the steepening effect of higher-order corrections leads first to the breakdown of single-field slow-roll and after that to the onset of 2-field dynamics: the overall volume of the extra dimensions starts to participate in the effective dynamics. Finally, we propose effective supergravity models of fibre inflation based on an \\overline{D3} uplift term with a nilpotent superfield. Specific moduli dependent \\overline{D3} induced geometries lead to cosmological fibre models but have in addition a de Sitter minimum exit. These supergravity models motivated by fibre inflation are relatively simple, stabilize the axions and disentangle the Hubble parameter from supersymmetry breaking.
Particle cosmology comes of age
International Nuclear Information System (INIS)
Turner, M.S.
1988-01-01
The application of modern ideas in particle physics to astrophysical and cosmological settings is a continuation of a fruitful tradition in astrophysics which began with the application of atomic physics, and then nuclear physics. In the past decade particle cosmology and particle astrophysics have been recognized as 'legitimate activities' by both particle physicists and astrophysicists and astronomers. During this time there has been a high level of theoretical activity producing much speculation about the earliest history of the Universe, as well as important and interesting astrophysical and cosmological constraints to particle physics theories. This period of intense theoretical activity has produced a number of ideas most worthy of careful consideration and scrutiny, and even more importantly, amenable to experimental/observational test. Among the ideas which are likely to be tested in the next decade are: the cosmological bound to the number of neutrino flavors, inflation, relic WIMPs as the dark matter, and MSW neutrino oscillations as a solution to the solar neutrino problems. (orig.)
Particle cosmology comes of age
International Nuclear Information System (INIS)
Turner, M.S.
1987-12-01
The application of modern ideas in particle physics to astrophysical and cosmological settings is a continuation of a fruitful tradition in astrophysics which began with the application of atomic physics, and then nuclear physics. In the past decade particle cosmology and particle astrophysics have been recognized as 'legitimate activities' by both particle physicists and astrophysicists and astronomers. During this time there has been a high level of theoretical activity producing much speculation about the earliest history of the Universe, as well as important and interesting astrophysical and cosmological constraints to particle physics theories. This period of intense theoretical activity has produced a number of ideas most worthy of careful consideration and scrutiny, and even more importantly, amenable to experimental/observational test. Among the ideas which are likely to be tested in the next decade are: the cosmological bound to the number of neutrino flavors, inflation, relic WIMPs as the dark matter, and MSW neutrino oscillations as a solution to the solar neutrino problems. 94 refs
On the One Loop Corrections to Inflation II
DEFF Research Database (Denmark)
Sloth, Martin Snoager
2006-01-01
In this paper we extend our previous treatment of the one-loop corrections to inflation. Previously we calculated the one-loop corrections to the background and the two-point correlation function of inflaton fluctuations in a specific model of chaotic inflation. We showed that the loop correction...... model of chaotic inflation with a quadratic inflationary potential. We discuss the physical interpretation of the effect in terms of the tensor-to-scalar consistency relation. Finally, we discuss the relation to the work of Weinberg on quantum contributions to cosmological correlators....
Constraining holographic cosmology using Planck data
Afshordi, Niayesh; Gould, Elizabeth; Skenderis, Kostas
2017-06-01
Holographic cosmology offers a novel framework for describing the very early Universe in which cosmological predictions are expressed in terms of the observables of a three-dimensional quantum field theory (QFT). This framework includes conventional slow-roll inflation, which is described in terms of a strongly coupled QFT, but it also allows for qualitatively new models for the very early Universe, where the dual QFT may be weakly coupled. The new models describe a universe which is nongeometric at early times. While standard slow-roll inflation leads to a (near-) power-law primordial power spectrum, perturbative super-renormalizable QFTs yield a new holographic spectral shape. Here, we compare the two predictions against cosmological observations. We use CosmoMC to determine the best fit parameters, and MultiNest for Bayesian evidence, comparing the likelihoods. We find that the dual QFT should be nonperturbative at the very low multipoles (l ≲30 ), while for higher multipoles (l ≳30 ) the new holographic model, based on perturbative QFT, fits the data just as well as the standard power-law spectrum assumed in Λ CDM cosmology. This finding opens the door to applications of nonperturbative QFT techniques, such as lattice simulations, to observational cosmology on gigaparsec scales and beyond.
Reheating for closed string inflation
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Mazumdar, Anupam [Lancaster Univ. (United Kingdom). Physics Dept.; Copenhagen Univ. (Denmark). Niels Bohr Institute
2010-05-15
We point out some of the outstanding challenges for embedding inflationary cosmology within string theory studying the process of reheating for models where the inflaton is a closed string mode parameterising the size of an internal cycle of the compactification manifold. A realistic model of inflation must explain the tiny perturbations in the cosmic microwave background radiation and also how to excite the ordinary matter degrees of freedom after inflation, required for the success of Big Bang Nucleosynthesis. We study these issues focusing on two promising inflationary models embedded in LARGE volume type IIB flux compactifications. We show that phenomenological requirements and consistency of the effective field theory treatment imply the presence at low energies of a hidden sector together with a visible sector, where the Minimal Supersymmetric Standard Model fields are residing. A detailed calculation of the inflaton coupling to the fields of the hidden sector, visible sector, and moduli sector, reveals that the inflaton fails to excite primarily the visible sector fields, instead hidden sector fields are excited copiously after the end of inflation. This sets severe constraints on hidden sector model building where the most promising scenario emerges as a pure N=1 SYM theory, forbidding the kinematical decay of the inflaton to the hidden sector. In this case it is possible to reheat the Universe with the visible degrees of freedom even though in some cases we discover a new tension between TeV scale SUSY and reheating on top of the well-known tension between TeV scale SUSY and inflation. (orig.)
Reheating for closed string inflation
International Nuclear Information System (INIS)
Cicoli, Michele; Mazumdar, Anupam; Copenhagen Univ.
2010-05-01
We point out some of the outstanding challenges for embedding inflationary cosmology within string theory studying the process of reheating for models where the inflaton is a closed string mode parameterising the size of an internal cycle of the compactification manifold. A realistic model of inflation must explain the tiny perturbations in the cosmic microwave background radiation and also how to excite the ordinary matter degrees of freedom after inflation, required for the success of Big Bang Nucleosynthesis. We study these issues focusing on two promising inflationary models embedded in LARGE volume type IIB flux compactifications. We show that phenomenological requirements and consistency of the effective field theory treatment imply the presence at low energies of a hidden sector together with a visible sector, where the Minimal Supersymmetric Standard Model fields are residing. A detailed calculation of the inflaton coupling to the fields of the hidden sector, visible sector, and moduli sector, reveals that the inflaton fails to excite primarily the visible sector fields, instead hidden sector fields are excited copiously after the end of inflation. This sets severe constraints on hidden sector model building where the most promising scenario emerges as a pure N=1 SYM theory, forbidding the kinematical decay of the inflaton to the hidden sector. In this case it is possible to reheat the Universe with the visible degrees of freedom even though in some cases we discover a new tension between TeV scale SUSY and reheating on top of the well-known tension between TeV scale SUSY and inflation. (orig.)
The hybrid inflation waterfall and the primordial curvature perturbation
International Nuclear Information System (INIS)
Lyth, David H.
2012-01-01
Without demanding a specific form for the inflaton potential, we obtain an estimate of the contribution to the curvature perturbation generated during the linear era of the hybrid inflation waterfall. The spectrum of this contribution peaks at some wavenumber k = k * , and goes like k 3 for k * , making it typically negligible on cosmological scales. The scale k * can be outside the horizon at the end of inflation, in which case ζ = −(g 2 −(g 2 )) with g gaussian. Taking this into account, the cosmological bound on the abundance of black holes is likely to be satisfied if the curvaton mass m much bigger than the Hubble parameter H, but is likely to be violated if m∼< H. Coming to the contribution to ζ from the rest of the waterfall, we are led to consider the use of the 'end-of-inflation' formula, giving the contribution to ζ generated during a sufficiently sharp transition from nearly-exponential inflation to non-inflation, and we state for the first time the criterion for the transition to be sufficiently sharp. Our formulas are applied to supersymmetric GUT inflation and to supernatural/running-mass inflation
The hybrid inflation waterfall and the primordial curvature perturbation
Lyth, David H.
2012-05-01
Without demanding a specific form for the inflaton potential, we obtain an estimate of the contribution to the curvature perturbation generated during the linear era of the hybrid inflation waterfall. The spectrum of this contribution peaks at some wavenumber k = k*, and goes like k3 for k Lt k*, making it typically negligible on cosmological scales. The scale k* can be outside the horizon at the end of inflation, in which case ζ = -(g2-langg2rang) with g gaussian. Taking this into account, the cosmological bound on the abundance of black holes is likely to be satisfied if the curvaton mass m much bigger than the Hubble parameter H, but is likely to be violated if mlsimH. Coming to the contribution to ζ from the rest of the waterfall, we are led to consider the use of the `end-of-inflation' formula, giving the contribution to ζ generated during a sufficiently sharp transition from nearly-exponential inflation to non-inflation, and we state for the first time the criterion for the transition to be sufficiently sharp. Our formulas are applied to supersymmetric GUT inflation and to supernatural/running-mass inflation. A preliminary version of this paper appeared as arXiv:1107.1681.
The hybrid inflation waterfall and the primordial curvature perturbation
Energy Technology Data Exchange (ETDEWEB)
Lyth, David H., E-mail: d.lyth@lancaster.ac.uk [Consortium for Fundamental Physics, Cosmology and Astroparticle Group, Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)
2012-05-01
Without demanding a specific form for the inflaton potential, we obtain an estimate of the contribution to the curvature perturbation generated during the linear era of the hybrid inflation waterfall. The spectrum of this contribution peaks at some wavenumber k = k{sub *}, and goes like k{sup 3} for k << k{sub *}, making it typically negligible on cosmological scales. The scale k{sub *} can be outside the horizon at the end of inflation, in which case ζ = −(g{sup 2}−(g{sup 2})) with g gaussian. Taking this into account, the cosmological bound on the abundance of black holes is likely to be satisfied if the curvaton mass m much bigger than the Hubble parameter H, but is likely to be violated if m∼
General very special relativity in Finsler cosmology
International Nuclear Information System (INIS)
Kouretsis, A. P.; Stathakopoulos, M.; Stavrinos, P. C.
2009-01-01
General very special relativity (GVSR) is the curved space-time of very special relativity (VSR) proposed by Cohen and Glashow. The geometry of general very special relativity possesses a line element of Finsler geometry introduced by Bogoslovsky. We calculate the Einstein field equations and derive a modified Friedmann-Robertson-Walker cosmology for an osculating Riemannian space. The Friedmann equation of motion leads to an explanation of the cosmological acceleration in terms of an alternative non-Lorentz invariant theory. A first order approach for a primordial-spurionic vector field introduced into the metric gives back an estimation of the energy evolution and inflation.
Cosmological implications of Higgs near-criticality.
Espinosa, J R
2018-03-06
The Standard Model electroweak (EW) vacuum, in the absence of new physics below the Planck scale, lies very close to the boundary between stability and metastability, with the last option being the most probable. Several cosmological implications of this so-called 'near-criticality' are discussed. In the metastable vacuum case, the main challenges that the survival of the EW vacuum faces during the evolution of the Universe are analysed. In the stable vacuum case, the possibility of implementing Higgs inflation is critically examined.This article is part of the Theo Murphy meeting issue 'Higgs cosmology'. © 2018 The Author(s).
Soft theorems for shift-symmetric cosmologies
Finelli, Bernardo; Goon, Garrett; Pajer, Enrico; Santoni, Luca
2018-03-01
We derive soft theorems for single-clock cosmologies that enjoy a shift symmetry. These so-called consistency conditions arise from a combination of a large diffeomorphism and the internal shift symmetry and fix the squeezed limit of all correlators with a soft scalar mode. As an application, we show that our results reproduce the squeezed bispectrum for ultra-slow-roll inflation, a particular shift-symmetric, nonattractor model which is known to violate Maldacena's consistency relation. Similar results have been previously obtained by Mooij and Palma using background-wave methods. Our results shed new light on the infrared structure of single-clock cosmological spacetimes.
Cosmological reconstruction of realistic modified F(R) gravities
International Nuclear Information System (INIS)
Nojiri, Shin'ichi; Odintsov, Sergei D.; Saez-Gomez, Diego
2009-01-01
The cosmological reconstruction scheme for modified F(R) gravity is developed in terms of e-folding (or, redshift). It is demonstrated how any FRW cosmology may emerge from specific F(R) theory. The specific examples of well-known cosmological evolution are reconstructed, including ΛCDM cosmology, deceleration with transition to phantom superacceleration era which may develop singularity or be transient. The application of this scheme to viable F(R) gravities unifying inflation with dark energy era is proposed. The additional reconstruction of such models leads to non-leading gravitational correction mainly relevant at the early/late universe and helping to pass the cosmological bounds (if necessary). It is also shown how cosmological reconstruction scheme may be generalized in the presence of scalar field.
International Nuclear Information System (INIS)
Liu, Yang; Piao, Yun-Song; Si, Zong-Guo
2009-01-01
In this paper, we revisit the idea of locked inflation, which does not require a potential satisfying the normal slow-roll condition, but suffers from the problems associated with ''saddle inflation''. We propose a scenario based on locked inflation, however, with an alternative evolution mechanism of the ''waterfall field'' φ. Instead of rolling down along the potential, the φ field will tunnel to end the inflation stage like in old inflation, by which the saddle inflation could be avoided. Further, we study a cascade of old locked inflation, which can be motivated by the string landscape. Our model is based on the consideration of making locked inflation feasible so as to give a working model without slow roll; It also can be seen as an effort to embed the old inflation in string landscape
Energy Technology Data Exchange (ETDEWEB)
Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kobayashi, Tsutomu [Kyoto Univ. (Japan). Hakubi Center; Kyoto Univ. (Japan). Dept. of Physics; Takahashi, Tomo [Saga Univ. (Japan). Dept. of Physics; Yamaguchi, Masahide [Tokyo Institute of Technology (Japan). Dept. of Physics; Yokoyama, Jun' ichi [Tokyo Univ. (JP). Research Center for the Early Universe (RESCEU); Tokyo Univ., Chiba (JP). Inst. for the Physics and Mathematics of the Universe (IPMU)
2012-03-15
We study Higgs inflation in the context of generalized G-inflation, i.e., the most general single-field inflation model with second-order field equations. The four variants of Higgs inflation proposed so far in the literature can be accommodated at one time in our framework. We also propose yet another class of Higgs inflation, the running Einstein inflation model, that can naturally arise from the generalized G-inflation framework. As a result, five Higgs inflation models in all should be discussed on an equal footing. Concise formulas for primordial fluctuations in these generalized Higgs inflation models are provided, which will be helpful to determine which model is favored from the future experiments and observations such as the Large Hadron Collider and the Planck satellite.
A Signature of Inflation from Dynamical Supersymmetry Breaking
Kinney, W H; Kinney, William H.; Riotto, Antonio
1998-01-01
In models of cosmological inflation motivated by dynamical supersymmetry breaking, the potential driving inflation may be characterized by inverse powers of a scalar field. These models produce observables similar to those typical of the hybrid inflation scenario: negligible production of tensor (gravitational wave) modes, and a blue scalar spectral index. In this short note, we show that, unlike standard hybrid inflation models, dynamical supersymmetric inflation (DSI) predicts a measurable deviation from a power-law spectrum of fluctuations, with a variation in the scalar spectral index $|dn / d(\\ln k)|$ may be as large as 0.05. DSI can be observationally distinguished from other hybrid models with cosmic microwave background measurements of the planned sensitivity of the ESA's Planck Surveyor.
End of multifield inflation and the perturbation spectrum
International Nuclear Information System (INIS)
Gong, Jinn-Ouk
2007-01-01
We investigate the dynamics of inflation models driven by multiple, decoupled scalar fields and calculate the Hubble parameter and the amplitude of the lightest field at the end of inflation which may be responsible for interesting, or possibly dangerous cosmological consequences after inflation. The results are very simple and similar to those of the single field inflation, mainly depending on the underlying spectrum of the masses. The mass distribution is heavily constrained by the power spectrum of density perturbations P and the spectral index n s . The overall mass scale gives the amplitude of P, and n s is affected by the number of fields and the spacing between masses in the distribution. The dropout effect of the massive fields makes the perturbation spectrum typically redder than the single field inflation spectrum. We illustrate this using two different mass distributions
TIME AND ETERNITY FROM PLOTINUS AND BOETHIUS TO EINSTEIN
Directory of Open Access Journals (Sweden)
Chase, Michael
2014-01-01
Full Text Available This article seeks to show that the views on time and eternity of Plotinus and Boethius are analogous to those implied by the block-time perspective in contemporary philosophy of time, as implied by the mathematical physics of Einstein and Minkowski. Both Einstein and Boethius utilized their theories of time and eternity with the practical goal of providing consolation to persons in distress; this practice of consolatio is compared to Pierre Hadot’s studies of the “Look from Above”, of the importance of concentrating on the present moment, and his emphasis on ancient philosophy as providing therapy for the soul, instead of mere abstract speculation for its own sake. In the first part of the article, Einstein’s views are compared with those of Plotinus, and with the elucidation of Plotinus’ views provided in the Arabic Theology of Aristotle. The second part of the article studies Boethius’ Consolation of Philosophy, which, contrary to recent interpretations, is indeed a genuine consolation rather than a parody thereof. The Consolation shows how the study of the Neoplatonic philosophical curriculum can lead the student along the path to salvation, by awakening and elaborating his innate ideas. To illustrate this doctrine, a passage from the little-known Pseudo-Boethian treatise De diis et praesensionibus is studied. Finally, after a survey of Boethius’ view on fate and providence, and Aristotle’s theory of future contingents, I study Boethius’ three main arguments in favor of the reconcilability of divine omniscience and human free will: the distinction between absolute and conditional necessity, the principle that the nature of knowledge is determined by the knower, and finally the doctrine that God lives in an eternal present, seeing past, present, and future simultaneously. This last view, developed primarily from Plotinus, is once again argued to be analogous to that advocated by contemporary block-time theorists on the basis
Grant, E.; Murdin, P.
2000-11-01
During the early Middle Ages (ca 500 to ca 1130) scholars with an interest in cosmology had little useful and dependable literature. They relied heavily on a partial Latin translation of PLATO's Timaeus by Chalcidius (4th century AD), and on a series of encyclopedic treatises associated with the names of Pliny the Elder (ca AD 23-79), Seneca (4 BC-AD 65), Macrobius (fl 5th century AD), Martianus ...
Gratton, Steven
2011-09-01
In this paper we present a path integral formulation of stochastic inflation. Volume weighting can be naturally implemented from this new perspective in a very straightforward way when compared to conventional Langevin approaches. With an in-depth study of inflation in a quartic potential, we investigate how the inflaton evolves and how inflation typically ends both with and without volume weighting. The calculation can be carried to times beyond those accessible to conventional Fokker-Planck approaches. Perhaps unexpectedly, complex histories sometimes emerge with volume weighting. The reward for this excursion into the complex plane is an insight into how volume-weighted inflation both loses memory of initial conditions and ends via slow roll. The slow-roll end of inflation mitigates certain “Youngness Paradox”-type criticisms of the volume-weighted paradigm. Thus it is perhaps time to rehabilitate proper-time volume weighting as a viable measure for answering at least some interesting cosmological questions.
International Nuclear Information System (INIS)
Gratton, Steven
2011-01-01
In this paper we present a path integral formulation of stochastic inflation. Volume weighting can be naturally implemented from this new perspective in a very straightforward way when compared to conventional Langevin approaches. With an in-depth study of inflation in a quartic potential, we investigate how the inflaton evolves and how inflation typically ends both with and without volume weighting. The calculation can be carried to times beyond those accessible to conventional Fokker-Planck approaches. Perhaps unexpectedly, complex histories sometimes emerge with volume weighting. The reward for this excursion into the complex plane is an insight into how volume-weighted inflation both loses memory of initial conditions and ends via slow roll. The slow-roll end of inflation mitigates certain ''Youngness Paradox''-type criticisms of the volume-weighted paradigm. Thus it is perhaps time to rehabilitate proper-time volume weighting as a viable measure for answering at least some interesting cosmological questions.
International Nuclear Information System (INIS)
Partridge, R.B.
1977-01-01
Some sixty years after the development of relativistic cosmology by Einstein and his colleagues, observations are finally beginning to have an important impact on our views of the Universe. The available evidence seems to support one of the simplest cosmological models, the hot Big Bang model. The aim of this paper is to assess the observational support for certain assumptions underlying the hot Big Bang model. These are that the Universe is isobaric and homogeneous on a large scale; that it is expanding from an initial state of high density and temperature; and that the proper theory to describe the dynamics of the Universe is unmodified General Relativity. The properties of the cosmic microwave background radiation and recent observations of the abundance of light elements, in particular, support these assumptions. Also examined here are the data bearing on the related questions of the geometry and the future of the Universe (is it ever-expanding, or fated to recollapse). Finally, some difficulties and faults of the standard model are discussed, particularly various aspects of the 'initial condition' problem. It appears that the simplest Big Bang cosmological model calls for a highly specific set of initial conditions to produce the presently observed properties of the Universe. (Auth.)
the Universe About Cosmology Planck Satellite Launched Cosmology Videos Professor George Smoot's group conducts research on the early universe (cosmology) using the Cosmic Microwave Background radiation (CMB science goals regarding cosmology. George Smoot named Director of Korean Cosmology Institute The GRB
The effective field theory of nonsingular cosmology: II
Energy Technology Data Exchange (ETDEWEB)
Cai, Yong; Li, Hai-Guang [University of Chinese Academy of Sciences, School of Physics, Beijing (China); Qiu, Taotao [Central China Normal University, Institute of Astrophysics, Wuhan (China); Piao, Yun-Song [University of Chinese Academy of Sciences, School of Physics, Beijing (China); Chinese Academy of Sciences, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)
2017-06-15
Based on the effective field theory (EFT) of cosmological perturbations, we explicitly clarify the pathology in nonsingular cubic Galileon models and show how to cure it in EFT with new insights into this issue. With the least set of EFT operators that are capable to avoid instabilities in nonsingular cosmologies, we construct a nonsingular model dubbed the Genesis-inflation model, in which a slowly expanding phase (namely, Genesis) with increasing energy density is followed by slow-roll inflation. The spectrum of the primordial perturbation may be simulated numerically, which shows itself a large-scale cutoff, as the large-scale anomalies in CMB might be a hint for. (orig.)
The Eternal Role of Astronomy in History and Civilization
Theodossiou, E.; Manimanis, V. N.
2010-07-01
Astronomy is the most ancient of all natural sciences. From its roots in ancient Babylonian and Egyptian stellar observations, and through its formulation into a science from the Greek natural philosophers, it defined the measurement of time. The stellar eras and the applications of Astronomy were incorporated in temples, paintings, sculptures and in art in general. Today, the value of Astronomy on practical matters, timekeeping or the navigation, has diminished. However, the eternal questions connected with Astronomy remain: Who are we and where did we come from? How and why was the Universe born? The greatest step to answer this kind of questions came with the so-called Copernican revolution, mostly in the 17th Century. The progress of Astronomy in the 400 years since then answered questions and gave an end to all kinds of superstitions, one more contribution to human civilization.
Descartes on the Creation of the Eternal Truths
Directory of Open Access Journals (Sweden)
Danielle Macbeth
2017-06-01
Full Text Available On 15 April 1630, in a letter to Mersenne, Descartes announced that on his view God creates the truths of mathematics. Descartes returned to the theme in subsequent letters and some of his Replies but nowhere is the view systematically developed and defended. It is not clear why Descartes came to espouse the creation doctrine, nor even what exactly it is. Some have argued that his motivation was theological, that God creates the eternal truths, including the truths of logic, because and insofar as God is omnipotent andthe creator of all things. I develop and defend a different reading according to which Descartes was led to espouse the creation doctrine by a fundamental shift in his understanding of the correct mode of inquiry in metaphysics and mathematics: by 1630, the God-created truths came to play the role in inquiry that until then, in the Rules for the Direction of the Mind, had been played by images.
The Price of Eternal Vigilance: Women and Intoxication
Directory of Open Access Journals (Sweden)
Michelle McClellan
2016-04-01
Full Text Available The Price of Eternal Vigilance: Women and Intoxication by Michelle McClellan. The author argues that the “cultural meaning of intoxication is shaped profoundly by the reality that we seem to only hear about it from women who have given it up.” This is a problem when it obscures the reasons why women seek out alcohol. Resisting the seemingly inevitable trajectory of addiction and recovery narratives, McClellan introduces the concepts of “dry” and “wet” feminism to draw attention to both the cultural expectations women face and the ways that intoxication might serve as a form of resistance. By refusing to see intoxication as a sort of false consciousness from which women must awake, McClellan demonstrates that it reflects female ambivalence about mothering, sexuality, and pleasure itself.
Eternal 5D optical data storage in glass (Conference Presentation)
Kazansky, Peter G.; Cerkauskaite, Ausra; Drevinskas, Rokas; Zhang, Jingyu
2016-09-01
A decade ago it has been discovered that during femtosecond laser writing self-organized subwavelength structures with record small features of 20 nm, could be created in the volume of silica glass. On the macroscopic scale the self-assembled nanostructure behaves as a uniaxial optical crystal with negative birefringence. The optical anisotropy, which results from the alignment of nano-platelets, referred to as form birefringence, is of the same order of magnitude as positive birefringence in crystalline quartz. The two independent parameters describing birefringence, the slow axis orientation (4th dimension) and the strength of retardance (5th dimension), are explored for the optical encoding of information in addition to three spatial coordinates. The slow axis orientation and the retardance are independently manipulated by the polarization and intensity of the femtosecond laser beam. The data optically encoded into five dimensions is successfully retrieved by quantitative birefringence measurements. The storage allows unprecedented parameters including hundreds of terabytes per disc data capacity and thermal stability up to 1000°. Even at elevated temperatures of 160oC, the extrapolated decay time of nanogratings is comparable with the age of the Universe - 13.8 billion years. The recording of the digital documents, which will survive the human race, including the eternal copies of Universal Declaration of Human Rights, Newton's Opticks, Kings James Bible and Magna Carta, is a vital step towards an eternal archive. Additionally, a number of projects (such as Time Capsule to Mars, MoonMail, and the Google Lunar XPRIZE) could benefit from the technique's extreme durability, which fulfills a crucial requirement for storage on the Moon or Mars.
Inflation persistence in African countries: Does inflation targeting matter?
Phiri, Andrew
2016-01-01
This study investigates inflation persistence in annual CPI inflation collected between 1994 and 2014 for 46 African countries. We group these countries into panels according to whether they are inflation targeters or not and conduct estimations for pre and post inflation targeting periods. Interestingly enough, we find that inflation persistence was much higher for inflation targeters in periods before adopting their inflation targeting regimes and inflation persistence dropped by 40 percent...
Inflation and Dark Energy with a Single Superfield
Linde, Andrei; Roest, Diederik; Scalisi, Marco
2015-01-01
We discuss the possibility to construct supergravity models with a single superfield describing inflation as well as the tiny cosmological constant $V \\sim 10^{{-120}}$. One could expect that the simplest way to do it is to study models with a supersymmetric Minkowski vacuum and then slightly uplift
Energy Technology Data Exchange (ETDEWEB)
Notari, Alessio [Departament de Física Fondamental i Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, Barcelona, 08028 Spain (Spain); Tywoniuk, Konrad, E-mail: notari@ffn.ub.es, E-mail: konrad.tywoniuk@cern.ch [Theoretical Physics Department, CERN, Geneva (Switzerland)
2016-12-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term φ/ f {sub γ} F ∼ F , such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρ{sub R}, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff f {sub γ}, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if f {sub γ} is smaller than the field excursion φ{sub 0} by about a factor of at least O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4–5 efolds and an amplitude which is typically less than a few percent and decreases linearly with f {sub γ}. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρ{sub R} rather than φ-dot {sup 2}/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/ f {sub γ} to U(1) (photons) is much larger than the coupling 1/ f {sub G} to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed φ{sub 0∼} f {sub G}.
Inflation with a constant rate of roll
International Nuclear Information System (INIS)
Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi
2015-01-01
We consider an inflationary scenario where the rate of inflaton roll defined by ·· φ/H φ-dot remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs for unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime
Origin of density fluctuations in extended inflation
International Nuclear Information System (INIS)
Kolb, E.W.; Salopek, D.S.; Turner, M.S.
1990-05-01
The density fluctuations (both curvature and isocurvature) that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory are calculated. Curvature fluctuations arise due to quantum fluctuations in the Brans-Dicke field, in general have a nonscale-invariant spectrum, and can have an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The density perturbations that arise due to the inflation field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential and the usual formula for the amplitude of curvature perturbations applies
Introduction to particle cosmology the standard model of cosmology and its open problems
Bambi, Cosimo
2016-01-01
This book introduces the basic concepts of particle cosmology and covers all the main aspects of the Big Bang Model (expansion of the Universe, Big Bang Nucleosynthesis, Cosmic Microwave Background, large scale structures) and the search for new physics (inflation, baryogenesis, dark matter, dark energy). It also includes the majority of recent discoveries, such as the precise determination of cosmological parameters using experiments like WMAP and Planck, the discovery of the Higgs boson at LHC, the non-discovery to date of supersymmetric particles, and the search for the imprint of gravitational waves on the CMB polarization by Planck and BICEP. This textbook is based on the authors’ courses on Cosmology, and aims at introducing Particle Cosmology to senior undergraduate and graduate students. It has been especially written to be accessible even for those students who do not have a strong background in General Relativity and quantum field theory. The content of this book is organized in an easy-to-use ...
International Nuclear Information System (INIS)
Kolb, E.W.
1991-01-01
In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been reviewed. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result if inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models. (orig.)
International Nuclear Information System (INIS)
Kolb, E.W.; Chicago Univ., IL
1990-09-01
In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been revived. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result in inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models. 58 refs., 3 figs
String moduli inflation. An overview
Energy Technology Data Exchange (ETDEWEB)
Cicoli, Michele [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Quevedo, Fernando [Cambridge Univ. (United Kingdom). DAMTP/CMS; Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)
2011-06-15
We present an overview of inflationary models derived from string theory focusing mostly on closed string moduli as inflatons. After a detailed discussion of the {eta}-problem and different approaches to address it, we describe possible ways to obtain a de Sitter vacuum with all closed string moduli stabilised. We then look for inflationary directions and present some of the most promising scenarios where the inflatons are either the real or the imaginary part of Kaehler moduli. We pay particular attention on extracting potential observable implications, showing how most of the scenarios predict negligible gravitational waves and could therefore be ruled out by the Planck satellite. We conclude by briefly mentioning some open challenges in string cosmology beyond deriving just inflation. (orig.)
String moduli inflation. An overview
International Nuclear Information System (INIS)
Cicoli, Michele; Quevedo, Fernando
2011-06-01
We present an overview of inflationary models derived from string theory focusing mostly on closed string moduli as inflatons. After a detailed discussion of the η-problem and different approaches to address it, we describe possible ways to obtain a de Sitter vacuum with all closed string moduli stabilised. We then look for inflationary directions and present some of the most promising scenarios where the inflatons are either the real or the imaginary part of Kaehler moduli. We pay particular attention on extracting potential observable implications, showing how most of the scenarios predict negligible gravitational waves and could therefore be ruled out by the Planck satellite. We conclude by briefly mentioning some open challenges in string cosmology beyond deriving just inflation. (orig.)
Retrofitting models of inflation
International Nuclear Information System (INIS)
Kain, Ben
2009-01-01
I use the method of retrofitting, developed by Dine, Feng and Silverstein, to generate the scale of inflation dynamically, allowing it to be naturally small. This is a general procedure that may be performed on existing models of supersymmetric inflation. I illustrate this idea on two such models, one an example of F-term inflation and the other an example of D-term inflation.
Can inflation explain the second law of thermodynamics
International Nuclear Information System (INIS)
Page, D.N.; Pennsylvania State Univ., University Park
1984-01-01
The inflationary model of the universe can explain several of the cosmological conundra that are mysteries in the standard hot big bang model. Paul Davies has suggested that inflation can also explain the second law of thermodynamics, which describes the time asymmetry of the universe. Here several difficulties with this suggestion are noted showing how the present inflationary models must assume the arrow of time rather than explaining it. If the second law is formulated as a consequence of the hypothesis that there were no long-range spatial correlations in the initial state of the universe, it is shown how some of the cosmological conundra might be explained even without inflation. But if the ultimate explanation is to include inflation, three essential elements remain to be demonstrated which are listed. (author)
Brandenberger, Robert H.
2008-01-01
String gas cosmology is a string theory-based approach to early universe cosmology which is based on making use of robust features of string theory such as the existence of new states and new symmetries. A first goal of string gas cosmology is to understand how string theory can effect the earliest moments of cosmology before the effective field theory approach which underlies standard and inflationary cosmology becomes valid. String gas cosmology may also provide an alternative to the curren...
Inflation Protected Investment Strategies
Directory of Open Access Journals (Sweden)
Mirco Mahlstedt
2016-03-01
Full Text Available In this paper, a dynamic inflation-protected investment strategy is presented, which is based on traditional asset classes and Markov-switching models. Different stock market, as well as inflation regimes are identified, and within those regimes, the inflation hedging potential of stocks, bonds, real estate, commodities and gold are investigated. Within each regime, we determine optimal investment portfolios driven by the investment idea of protection from losses due to changing inflation if inflation is rising or high, but decoupling the performance from inflation if inflation is low. The results clearly indicate that these asset classes behave differently in different stock market and inflation regimes. Whereas in the long-run, we agree with the general opinion in the literature that stocks and bonds are a suitable hedge against inflation, we observe for short time horizons that the hedging potential of each asset class, especially of real estate and commodities, depend strongly on the state of the current market environment. Thus, our approach provides a possible explanation for different statements in the literature regarding the inflation hedging properties of these asset classes. A dynamic inflation-protected investment strategy is developed, which combines inflation protection and upside potential. This strategy outperforms standard buy-and-hold strategies, as well as the well-known 1 N -portfolio.
Energy Technology Data Exchange (ETDEWEB)
Ferreira, Ricardo Z.; Notari, Alessio, E-mail: rferreira@icc.ub.edu, E-mail: notari@ub.edu [Departament de Física Quàntica i Astrofísica i Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès, 1, E-08028, Barcelona (Spain)
2017-09-01
We analyze the dynamics of inflationary models with a coupling of the inflaton φ to gauge fields of the form φ F F-tilde / f , as in the case of axions. It is known that this leads to an instability, with exponential amplification of gauge fields, controlled by the parameter ξ= φ-dot /(2 fH ), which can strongly affect the generation of cosmological perturbations and even the background. We show that scattering rates involving gauge fields can become larger than the expansion rate H , due to the very large occupation numbers, and create a thermal bath of particles of temperature T during inflation. In the thermal regime, energy is transferred to smaller scales, radically modifying the predictions of this scenario. We thus argue that previous constraints on ξ are alleviated. If the gauge fields have Standard Model interactions, which naturally provides reheating, they thermalize already at ξ∼>2.9, before perturbativity constraints and also before backreaction takes place. In absence of SM interactions (i.e. for a dark photon), we find that gauge fields and inflaton perturbations thermalize if ξ∼>3.4; however, observations require ξ∼>6, which is above the perturbativity and backreaction bounds and so a dedicated study is required. After thermalization, though, the system should evolve non-trivially due to the competition between the instability and the gauge field thermal mass. If the thermal mass and the instabilities equilibrate, we expect an equilibrium temperature of T {sub eq} ≅ ξ H / g-bar where g-bar is the effective gauge coupling. Finally, we estimate the spectrum of perturbations if φ is thermal and find that the tensor to scalar ratio is suppressed by H /(2 T ), if tensors do not thermalize.
Ferreira, Ricardo Z.; Notari, Alessio
2017-09-01
We analyze the dynamics of inflationary models with a coupling of the inflaton phi to gauge fields of the form phi F tilde F/f, as in the case of axions. It is known that this leads to an instability, with exponential amplification of gauge fields, controlled by the parameter ξ= dot phi/(2fH), which can strongly affect the generation of cosmological perturbations and even the background. We show that scattering rates involving gauge fields can become larger than the expansion rate H, due to the very large occupation numbers, and create a thermal bath of particles of temperature T during inflation. In the thermal regime, energy is transferred to smaller scales, radically modifying the predictions of this scenario. We thus argue that previous constraints on ξ are alleviated. If the gauge fields have Standard Model interactions, which naturally provides reheating, they thermalize already at ξgtrsim2.9, before perturbativity constraints and also before backreaction takes place. In absence of SM interactions (i.e. for a dark photon), we find that gauge fields and inflaton perturbations thermalize if ξgtrsim3.4 however, observations require ξgtrsim6, which is above the perturbativity and backreaction bounds and so a dedicated study is required. After thermalization, though, the system should evolve non-trivially due to the competition between the instability and the gauge field thermal mass. If the thermal mass and the instabilities equilibrate, we expect an equilibrium temperature of Teq simeq ξ H/bar g where bar g is the effective gauge coupling. Finally, we estimate the spectrum of perturbations if phi is thermal and find that the tensor to scalar ratio is suppressed by H/(2T), if tensors do not thermalize.
Magnetohydrodynamic cosmologies
International Nuclear Information System (INIS)
Portugal, R.; Soares, I.D.
1991-01-01
We analyse a class of cosmological models in magnetohydrodynamic regime extending and completing the results of a previous paper. The material content of the models is a perfect fluid plus electromagnetic fields. The fluid is neutral in average but admits an electrical current which satisfies Ohm's law. All models fulfil the physical requirements of near equilibrium thermodynamics and can be favourably used as a more realistic description of the interior of a collapsing star in a magnetohydrodynamic regime with or without a magnetic field. (author)
Bardeen, J. M.
The last several years have seen a tremendous ferment of activity in astrophysical cosmology. Much of the theoretical impetus has come from particle physics theories of the early universe and candidates for dark matter, but what promise to be even more significant are improved direct observations of high z galaxies and intergalactic matter, deeper and more comprehensive redshift surveys, and the increasing power of computer simulations of the dynamical evolution of large scale structure. Upper limits on the anisotropy of the microwave background radiation are gradually getting tighter and constraining more severely theoretical scenarios for the evolution of the universe.
International Nuclear Information System (INIS)
Bardeen, J.M.
1986-01-01
The last several years have seen a tremendous ferment of activity in astrophysical cosmology. Much of the theoretical impetus has come from particle physics theories of the early universe and candidates for dark matter, but what promise to be even more significant are improved direct observations of high z galaxies and intergalactic matter, deeper and more comprehensive redshift surveys, and the increasing power of computer simulations of the dynamical evolution of large scale structure. Upper limits on the anisotropy of the microwave background radiation are gradually getting tighter and constraining more severely theoretical scenarios for the evolution of the universe. 47 refs
Boeyens, Jan CA
2010-01-01
The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp
Page, Don N.
2006-01-01
A complete model of the universe needs at least three parts: (1) a complete set of physical variables and dynamical laws for them, (2) the correct solution of the dynamical laws, and (3) the connection with conscious experience. In quantum cosmology, item (2) is the quantum state of the cosmos. Hartle and Hawking have made the `no-boundary' proposal, that the wavefunction of the universe is given by a path integral over all compact Euclidean 4-dimensional geometries and matter fields that hav...
Religion, theology and cosmology
Directory of Open Access Journals (Sweden)
John T. Fitzgerald
2013-10-01
Full Text Available Cosmology is one of the predominant research areas of the contemporary world. Advances in modern cosmology have prompted renewed interest in the intersections between religion, theology and cosmology. This article, which is intended as a brief introduction to the series of studies on theological cosmology in this journal, identifies three general areas of theological interest stemming from the modern scientific study of cosmology: contemporary theology and ethics; cosmology and world religions; and ancient cosmologies. These intersections raise important questions about the relationship of religion and cosmology, which has recently been addressed by William Scott Green and is the focus of the final portion of the article.
LIU Jinquan; ZHENG Tingguo; SUI Jianli
2008-01-01
This paper uses the ARFIMA-FIGARCH model to investigate the China¡¯s monthly inflation rate from January 1983 to October 2005. It is found that both first moment and second moment of inflation have remarkable long memory, indicating the existence of long memory properties in both inflation level and inflation uncertainty. By the Granger-causality test on inflation rate and inflation uncertainty, it is shown that the inflation level affects the inflation uncertainty and so supports Friedman hy...
Non-Abelian S-term dark energy and inflation
Rodríguez, Yeinzon; Navarro, Andrés A.
2018-03-01
We study the role that a cosmic triad in the generalized SU(2) Proca theory, specifically in one of the pieces of the Lagrangian that involves the symmetric version Sμν of the gauge field strength tensor Fμν, has on dark energy and primordial inflation. Regarding dark energy, the triad behaves asymptotically as a couple of radiation perfect fluids whose energy densities are negative for the S term but positive for the Yang-Mills term. This leads to an interesting dynamical fine-tuning mechanism that gives rise to a combined equation of state parameter ω ≃ - 1 and, therefore, to an eternal period of accelerated isotropic expansion for an ample spectrum of initial conditions. Regarding primordial inflation, one of the critical points of the associated dynamical system can describe a prolonged period of isotropic slow-roll inflation sustained by the S term. This period ends up when the Yang-Mills term dominates the energy density leading to the radiation dominated epoch. Unfortunately, in contrast to the dark energy case, the primordial inflation scenario is strongly sensitive to the coupling constants and initial conditions. The whole model, including the other pieces of the Lagrangian that involve Sμν, might evade the recent strong constraints coming from the gravitational wave signal GW170817 and its electromagnetic counterpart GRB 170817A.
Energy Technology Data Exchange (ETDEWEB)
Ivanov, Mikhail M.; Tokareva, Anna A., E-mail: mikhail.ivanov@cern.ch, E-mail: anna.tokareva@epfl.ch [Institute of Physics, LPPC, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne (Switzerland)
2016-12-01
We study the creation and evolution of cosmological perturbations in renormalizable quadratic gravity with a Weyl term. We adopt a prescription that implies the stability of the vacuum at the price of introducing a massive spin-two ghost state, leading to the loss of unitarity. The theory may still be predictive regardless the interpretation of non-unitary processes provided that their rate is negligible compared to the Universe expansion rate. This implies that the ghost is effectively stable. In such a setup, there are two scalar degrees of freedom excited during inflation. The first one is the usual curvature perturbation whose power spectrum appears to coincide with that of single-field inflation. The second one is a scalar component of the ghost encoded in the shift vector of the metric in the uniform inflaton gauge. The amplitudes of primordial tensor and vector perturbations are strongly suppressed. After inflation the ghost field starts to oscillate and its energy density shortly becomes dominant in the Universe. For all ghost masses allowed by laboratory constraints ghosts should have ''overclosed'' the Universe at temperatures higher than that of primordial nucleosynthesis. Thus, the model with the light Weyl ghost is ruled out.
Magnon Inflation: Slow Roll with Steep Potentials
Adshead, Peter; Burgess, C P; Hayman, Peter; Patil, Subodh P
2016-01-01
We find multi-scalar effective field theories (EFTs) that can achieve a slow inflationary roll despite having a scalar potential that does not satisfy the usual slow-roll condition (d V)^2 << V^2/Mp^2. They evade the usual slow-roll conditions on $V$ because their kinetic energies are dominated by single-derivative terms rather than the usual two-derivative terms. Single derivatives dominate during slow roll and so do not require a breakdown of the usual derivative expansion that underpins calculational control in much of cosmology. The presence of such terms requires some sort of UV Lorentz-symmetry breaking during inflation (besides the usual cosmological breaking). Chromo-natural inflation provides an example of a UV theory that can generate the multi-field single-derivative terms we consider, and we argue that the EFT we find indeed captures the slow-roll conditions for the background evolution for Chromo-natural inflation. We also show that our EFT can be understood as a multi-field generalization ...
Attractors, universality, and inflation
Downes, Sean; Dutta, Bhaskar; Sinha, Kuver
2012-11-01
Studies of the initial conditions for inflation have conflicting predictions from exponential suppression to inevitability. At the level of phase space, this conflict arises from the competing intuitions of CPT invariance and thermodynamics. After reviewing this conflict, we enlarge the ensemble beyond phase space to include scalar potential data. We show how this leads to an important contribution from inflection point inflation, enhancing the likelihood of inflation to a power law, 1/Ne3. In the process, we emphasize the attractor dynamics of the gravity-scalar system and the existence of universality classes from inflection point inflation. Finally, we comment on the predictivity of inflation in light of these results.
Finite canonical measure for nonsingular cosmologies
International Nuclear Information System (INIS)
Page, Don N.
2011-01-01
The total canonical (Liouville-Henneaux-Gibbons-Hawking-Stewart) measure is finite for completely nonsingular Friedmann-Lemaître-Robertson-Walker classical universes with a minimally coupled massive scalar field and a positive cosmological constant. For a cosmological constant very small in units of the square of the scalar field mass, most of the measure is for nearly de Sitter solutions with no inflation at a much more rapid rate. However, if one restricts to solutions in which the scalar field energy density is ever more than twice the equivalent energy density of the cosmological constant, then the number of e-folds of rapid inflation must be large, and the fraction of the measure is low in which the spatial curvature is comparable to the cosmological constant at the time when it is comparable to the energy density of the scalar field. The measure for such classical FLRWΛ-φ models with both a big bang and a big crunch is also finite. Only the solutions with a big bang that expand forever, or the time-reversed ones that contract from infinity to a big crunch, have infinite measure
Disformal transformation of cosmological perturbations
Directory of Open Access Journals (Sweden)
Masato Minamitsuji
2014-10-01
Full Text Available We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (nonconservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame.
The Age of Precision Cosmology
Chuss, David T.
2012-01-01
In the past two decades, our understanding of the evolution and fate of the universe has increased dramatically. This "Age of Precision Cosmology" has been ushered in by measurements that have both elucidated the details of the Big Bang cosmology and set the direction for future lines of inquiry. Our universe appears to consist of 5% baryonic matter; 23% of the universe's energy content is dark matter which is responsible for the observed structure in the universe; and 72% of the energy density is so-called "dark energy" that is currently accelerating the expansion of the universe. In addition, our universe has been measured to be geometrically flat to 1 %. These observations and related details of the Big Bang paradigm have hinted that the universe underwent an epoch of accelerated expansion known as Uinflation" early in its history. In this talk, I will review the highlights of modern cosmology, focusing on the contributions made by measurements of the cosmic microwave background, the faint afterglow of the Big Bang. I will also describe new instruments designed to measure the polarization of the cosmic microwave background in order to search for evidence of cosmic inflation.
Disformal transformation of cosmological perturbations
International Nuclear Information System (INIS)
Minamitsuji, Masato
2014-01-01
We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (non)conservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame
Cosmological aspects of spontaneous baryogenesis
Energy Technology Data Exchange (ETDEWEB)
Simone, Andrea De; Kobayashi, Takeshi [SISSA,Via Bonomea 265, 34136 Trieste (Italy); INFN, Sezione di Trieste,Via Bonomea 265, 34136 Trieste (Italy)
2016-08-24
We investigate cosmological aspects of spontaneous baryogenesis driven by a scalar field, and present general constraints that are independent of the particle physics model. The relevant constraints are obtained by studying the backreaction of the produced baryons on the scalar field, the cosmological expansion history after baryogenesis, and the baryon isocurvature perturbations. We show that cosmological considerations alone provide powerful constraints, especially for the minimal scenario with a quadratic scalar potential. Intriguingly, we find that for a given inflation scale, the other parameters including the reheat temperature, decoupling temperature of the baryon violating interactions, and the mass and decay constant of the scalar are restricted to lie within ranges of at most a few orders of magnitude. We also discuss possible extensions to the minimal setup, and propose two ideas for evading constraints on isocurvature perturbations: one is to suppress the baryon isocurvature with nonquadratic scalar potentials, another is to compensate the baryon isocurvature with cold dark matter isocurvature by making the scalar survive until the present.
Energy Technology Data Exchange (ETDEWEB)
Schramm, D.N.
1992-03-01
The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ``cold`` and ``hot`` non-baryonic candidates is shown to depend on the assumed ``seeds`` that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.
Energy Technology Data Exchange (ETDEWEB)
Schramm, D.N.
1992-03-01
The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the {Omega} = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between cold'' and hot'' non-baryonic candidates is shown to depend on the assumed seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed.
Perlov, Delia
2017-01-01
This book is an introductory text for all those wishing to learn about modern views of the cosmos. Our universe originated in a great explosion – the big bang. For nearly a century cosmologists have studied the aftermath of this explosion: how the universe expanded and cooled down, and how galaxies were gradually assembled by gravity. The nature of the bang itself has come into focus only relatively recently. It is the subject of the theory of cosmic inflation, which was developed in the last few decades and has led to a radically new global view of the universe. Students and other interested readers will find here a non-technical but conceptually rigorous account of modern cosmological ideas - describing what we know, and how we know it. One of the book's central themes is the scientific quest to find answers to the ultimate cosmic questions: Is the universe finite or infinite? Has it existed forever? If not, when and how did it come into being? Will it ever end? The book is based on the undergraduate cour...
International Nuclear Information System (INIS)
Schramm, D.N.
1992-03-01
The cosmological dark matter problem is reviewed. The Big Bang Nucleosynthesis constraints on the baryon density are compared with the densities implied by visible matter, dark halos, dynamics of clusters, gravitational lenses, large-scale velocity flows, and the Ω = 1 flatness/inflation argument. It is shown that (1) the majority of baryons are dark; and (2) non-baryonic dark matter is probably required on large scales. It is also noted that halo dark matter could be either baryonic or non-baryonic. Descrimination between ''cold'' and ''hot'' non-baryonic candidates is shown to depend on the assumed ''seeds'' that stimulate structure formation. Gaussian density fluctuations, such as those induced by quantum fluctuations, favor cold dark matter, whereas topological defects such as strings, textures or domain walls may work equally or better with hot dark matter. A possible connection between cold dark matter, globular cluster ages and the Hubble constant is mentioned. Recent large-scale structure measurements, coupled with microwave anisotropy limits, are shown to raise some questions for the previously favored density fluctuation picture. Accelerator and underground limits on dark matter candidates are also reviewed
Cosmological quantum entanglement
International Nuclear Information System (INIS)
Martín-Martínez, Eduardo; Menicucci, Nicolas C
2012-01-01
We review recent literature on the connection between quantum entanglement and cosmology, with an emphasis on the context of expanding universes. We discuss recent theoretical results reporting on the production of entanglement in quantum fields due to the expansion of the underlying spacetime. We explore how these results are affected by the statistics of the field (bosonic or fermionic), the type of expansion (de Sitter or asymptotically stationary), and the coupling to spacetime curvature (conformal or minimal). We then consider the extraction of entanglement from a quantum field by coupling to local detectors and how this procedure can be used to distinguish curvature from heating by their entanglement signature. We review the role played by quantum fluctuations in the early universe in nucleating the formation of galaxies and other cosmic structures through their conversion into classical density anisotropies during and after inflation. We report on current literature attempting to account for this transition in a rigorous way and discuss the importance of entanglement and decoherence in this process. We conclude with some prospects for further theoretical and experimental research in this area. These include extensions of current theoretical efforts, possible future observational pursuits, and experimental analogues that emulate these cosmic effects in a laboratory setting. (paper)
International Nuclear Information System (INIS)
Buchbinder, Evgeny I.; Khoury, Justin; Ovrut, Burt A.
2007-01-01
In this paper, we present a new scenario of the early universe that contains a pre-big bang ekpyrotic phase. By combining this with a ghost condensate, the theory explicitly violates the null energy condition without developing any ghostlike instabilities. Thus the contracting universe goes through a nonsingular bounce and evolves smoothly into the expanding post-big bang phase. The curvature perturbation acquires a scale-invariant spectrum well before the bounce in this scenario. It is sourced by the scale-invariant entropy perturbation engendered by two ekpyrotic scalar fields, a mechanism recently proposed by Lehners et al. Since the background geometry is nonsingular at all times, the curvature perturbation remains nearly constant on superhorizon scales. It emerges from the bounce unscathed and imprints a scale-invariant spectrum of density fluctuations in the matter-radiation fluid at the onset of the hot big bang phase. The ekpyrotic potential can be chosen so that the spectrum has a red tilt, in accordance with the recent data from WMAP. As in the original ekpyrotic scenario, the model predicts a negligible gravity wave signal on all observable scales. As such ''new ekpyrotic cosmology'' provides a consistent and distinguishable alternative to inflation to account for the origin of the seeds of large-scale structure
Brane world cosmologies with varying speed of light
International Nuclear Information System (INIS)
Youm, Donam
2001-02-01
We study cosmologies in the Randall-Sundrum models, incorporating the possibility of time-varying speed of light and Newton's constant. The cosmologies with varying speed of light (VSL) were proposed by Moffat and by Albrecht and Magueijo as an alternative to inflation for solving the cosmological problems. We consider the case in which the speed of light varies with time after the radion or the scale of the extra dimension has been stabilized. We elaborate on the conditions under which the flatness problem and the cosmological constant problem can be resolved. Particularly, the VSL cosmologies may provide a possible mechanism for bringing the quantum corrections to the fine-tuned brane tensions after the SUSY breaking under control. (author)
Scalar-tensor cosmology with cosmological constant
International Nuclear Information System (INIS)
Maslanka, K.
1983-01-01
The equations of scalar-tensor theory of gravitation with cosmological constant in the case of homogeneous and isotropic cosmological model can be reduced to dynamical system of three differential equations with unknown functions H=R/R, THETA=phi/phi, S=e/phi. When new variables are introduced the system becomes more symmetrical and cosmological solutions R(t), phi(t), e(t) are found. It is shown that when cosmological constant is introduced large class of solutions which depend also on Dicke-Brans parameter can be obtained. Investigations of these solutions give general limits for cosmological constant and mean density of matter in plane model. (author)
Krioukov, Dmitri; Kitsak, Maksim; Sinkovits, Robert S; Rideout, David; Meyer, David; Boguñá, Marián
2012-01-01
Prediction and control of the dynamics of complex networks is a central problem in network science. Structural and dynamical similarities of different real networks suggest that some universal laws might accurately describe the dynamics of these networks, albeit the nature and common origin of such laws remain elusive. Here we show that the causal network representing the large-scale structure of spacetime in our accelerating universe is a power-law graph with strong clustering, similar to many complex networks such as the Internet, social, or biological networks. We prove that this structural similarity is a consequence of the asymptotic equivalence between the large-scale growth dynamics of complex networks and causal networks. This equivalence suggests that unexpectedly similar laws govern the dynamics of complex networks and spacetime in the universe, with implications to network science and cosmology.
Eternal higher spin black holes: a thermofield Interpretation
International Nuclear Information System (INIS)
Castro, Alejandra; Iqbal, Nabil; Llabrés, Eva
2016-01-01
We study Lorentzian eternal black holes in the Chern-Simons sector of AdS 3 higher spin gravity. We probe such black holes using bulk Wilson lines and motivate new regularity conditions that must be obeyed by the bulk connections in order for the geometry to be consistent with an interpretation as a thermofield state in the dual CFT 2 . We demonstrate that any higher spin black hole may be placed in a gauge that satisfies these conditions: this is the Chern-Simons analogue of the construction of Kruskal coordinates that permit passage through the black hole horizon. We also argue that the Wilson line provides a higher-spin notion of causality in higher spin gravity that can be used to associate a Penrose diagram with the black hole. We present some applications of the formalism, including a study of the time-dependent entanglement entropy arising from the higher spin black hole interior and evidence for an emergent AdS 2 region in the extremal limit.
Alan Guth and Andrei Linde win international cosmology award
2004-01-01
"Leading theoretical cosmologists Alan Guth, Weisskopf Professor of Physics at the Massachusetts Institute of Technology, and Andrei Linde, Professor of Physics at Stanford University, who played prominent roles in developing and refining the theory of cosmic inflation, have been selected by an international panel of experts to receive the 2004 Cosmology Prize of the Peter Gruber Foundation" (1 page).
Inflation and dark energy arising from geometrical tachyons
International Nuclear Information System (INIS)
Panda, Sudhakar; Sami, M.; Tsujikawa, Shinji
2006-01-01
We study the motion of a Bogomol'nyi-Prasad-Sommerfield D3-brane in the NS5-brane ring background. The radion field becomes tachyonic in this geometrical setup. We investigate the potential of this geometrical tachyon in the cosmological scenario for inflation as well as dark energy. We evaluate the spectra of scalar and tensor perturbations generated during tachyon inflation and show that this model is compatible with recent observations of cosmic microwave background due to an extra freedom of the number of NS5-branes. It is not possible to explain the origin of both inflation and dark energy by using a single tachyon field, since the energy density at the potential minimum is not negligibly small because of the amplitude of scalar perturbations set by cosmic microwave background anisotropies. However, the geometrical tachyon can account for dark energy when the number of NS5-branes is large, provided that inflation is realized by another scalar field
Towards a formal link between inflation perceptions and inflation ...
African Journals Online (AJOL)
This paper reports the finding of a survey of inflation perceptions and inflation expectations in South Africa undertaken in 2014. This survey posed questions on perceptions of past inflation (historic inflation) and expectations of future inflation to the same respondents and determined linkages between historic views and ...
Can inflation solve the hierarchy problem?
International Nuclear Information System (INIS)
Biswas, Tirthabir; Notari, Alessio
2006-01-01
Inflation with tunneling from a false to a true vacuum becomes viable in the presence of a scalar field that slows down the initial de Sitter phase. As a by-product this field also sets dynamically the value of M Planck observed today. This can be very large if the tunneling rate (which is exponentially sensitive to the barrier) is small enough. Therefore along with inflation we also provide a natural dynamical explanation for why gravity is so weak today. Moreover we predict a spectrum of gravity waves peaked at around 0.1 mHz, that will be detectable by the planned space interferometer LISA. Finally we discuss interesting predictions on cosmological scalar and tensor fluctuations in light of the WMAP 3-year data
Metastable electroweak vacuum. Implications for inflation
Energy Technology Data Exchange (ETDEWEB)
Lebedev, Oleg; Westphal, Alexander [DESY Theory Group, Hamburg (Germany)
2012-10-15
Within the Standard Model, the current Higgs and top quark data favor metastability of the electroweak vacuum, although the uncertainties are still significant. The true vacuum is many orders of magnitude deeper than ours and the barrier separating the two is tiny compared to the depth of the well. This raises a cosmological question: how did the Higgs field get trapped in the shallow minimum and why did it stay there during inflation? The Higgs initial conditions before inflation must be fine-tuned to about one part in 10{sup 8} in order for the Higgs field to end up in the right vacuum. In this note, we show that these problems can be resolved if there is a small positive coupling between the Higgs and the inflaton.
New perspectives on constant-roll inflation
Cicciarella, Francesco; Mabillard, Joel; Pieroni, Mauro
2018-01-01
We study constant-roll inflation using the β-function formalism. We show that the constant rate of the inflaton roll is translated into a first order differential equation for the β-function which can be solved easily. The solutions to this equation correspond to the usual constant-roll models. We then construct, by perturbing these exact solutions, more general classes of models that satisfy the constant-roll equation asymptotically. In the case of an asymptotic power law solution, these corrections naturally provide an end to the inflationary phase. Interestingly, while from a theoretical point of view (in particular in terms of the holographic interpretation) these models are intrinsically different from standard slow-roll inflation, they may have phenomenological predictions in good agreement with present cosmological data.
Metastable electroweak vacuum. Implications for inflation
International Nuclear Information System (INIS)
Lebedev, Oleg; Westphal, Alexander
2012-10-01
Within the Standard Model, the current Higgs and top quark data favor metastability of the electroweak vacuum, although the uncertainties are still significant. The true vacuum is many orders of magnitude deeper than ours and the barrier separating the two is tiny compared to the depth of the well. This raises a cosmological question: how did the Higgs field get trapped in the shallow minimum and why did it stay there during inflation? The Higgs initial conditions before inflation must be fine-tuned to about one part in 10 8 in order for the Higgs field to end up in the right vacuum. In this note, we show that these problems can be resolved if there is a small positive coupling between the Higgs and the inflaton.
Origin of density fluctuations in extended inflation
International Nuclear Information System (INIS)
Kolb, E.W.; Salopek, D.S.; Turner, M.S.
1990-01-01
We calculate both the curvature and isocurvature density fluctuations that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory. The curvature fluctuations that arise due to quantum fluctuations in the Brans-Dicke field in general have a non-scale-invariant spectrum and an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The curvature perturbations that arise due to the Higgs field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential, and the usual formula for the amplitude of curvature perturbations applies directly
Inflation and pseudo-Goldstone Higgs boson
DEFF Research Database (Denmark)
Alanne, Tommi; Sannino, Francesco; Tenkanen, Tommi
2017-01-01
We consider inflation within a model framework where the Higgs boson arises as a pseudo-Goldstone boson associated with the breaking of a global symmetry at a scale significantly larger than the electroweak one. We show that in such a model the scalar self-couplings can be parametrically suppressed...... and, consequently, the nonminimal couplings to gravity can be of order one or less, while the inflationary predictions of the model remain compatible with the precision cosmological observations. Furthermore, in the model we study, the existence of the electroweak scale is entirely due to the inflaton...
Inflation and non-equilibrium dynamics
International Nuclear Information System (INIS)
Pi, S.
1989-01-01
Herman Feshbach is a premier nuclear physicist. Although I do no research in his physics subfield, I have found it useful to apply methods developed in that area to early universe investigations that rely on a field-theoretic description for the time evolution of pure and/or mixed initial states. On the occasion of his seventieth birthday, I offer for his enjoyment this essay in which I describe how time-dependent Hartree--Fock methods and their generalizations to mixed states are used in attempts to establish various cosmological scenarios, in particular, inflation. copyright 1989 Academic Press, Inc
Pseudosmooth tribrid inflation
Energy Technology Data Exchange (ETDEWEB)
Antusch, Stefan; Nolde, David; Rehman, Mansoor Ur, E-mail: stefan.antusch@unibas.ch, E-mail: david.nolde@unibas.ch, E-mail: mansoor-ur.rehman@unibas.ch [Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel (Switzerland)
2012-08-01
We explore a new class of supersymmetric models of inflation where the inflaton is realised as a combination of a Higgs field and (gauge non-singlet) matter fields, using a ''tribrid'' structure of the superpotential. Inflation is associated with a phase transition around GUT scale energies. The inflationary trajectory already preselects the later vacuum after inflation, which has the advantage of automatically avoiding the production of dangerous topological defects at the end of inflation. While at first sight the models look similar to smooth inflation, they feature a waterfall and are therefore only pseudosmooth. The new class of models offers novel possibilities for realising inflation in close contact with particle physics, for instance with supersymmetric GUTs or with supersymmetric flavour models based on family symmetries.
Pseudosmooth tribrid inflation
Antusch, Stefan; Nolde, David; Rehman, Mansoor Ur
2012-08-01
We explore a new class of supersymmetric models of inflation where the inflaton is realised as a combination of a Higgs field and (gauge non-singlet) matter fields, using a ``tribrid'' structure of the superpotential. Inflation is associated with a phase transition around GUT scale energies. The inflationary trajectory already preselects the later vacuum after inflation, which has the advantage of automatically avoiding the production of dangerous topological defects at the end of inflation. While at first sight the models look similar to smooth inflation, they feature a waterfall and are therefore only pseudosmooth. The new class of models offers novel possibilities for realising inflation in close contact with particle physics, for instance with supersymmetric GUTs or with supersymmetric flavour models based on family symmetries.
Pseudosmooth tribrid inflation
International Nuclear Information System (INIS)
Antusch, Stefan; Nolde, David; Rehman, Mansoor Ur
2012-01-01
We explore a new class of supersymmetric models of inflation where the inflaton is realised as a combination of a Higgs field and (gauge non-singlet) matter fields, using a ''tribrid'' structure of the superpotential. Inflation is associated with a phase transition around GUT scale energies. The inflationary trajectory already preselects the later vacuum after inflation, which has the advantage of automatically avoiding the production of dangerous topological defects at the end of inflation. While at first sight the models look similar to smooth inflation, they feature a waterfall and are therefore only pseudosmooth. The new class of models offers novel possibilities for realising inflation in close contact with particle physics, for instance with supersymmetric GUTs or with supersymmetric flavour models based on family symmetries
Inflation in the universe, Circa 1986
International Nuclear Information System (INIS)
Turner, M.S.
1986-12-01
The hot big bang cosmology, or the standard cosmology as it is appropriately known, is a highly successful model, providing a reliable and tested accounting of the Universe from 0.01 sec after the bang until today, some 15 Gyr later. However, very special initial data seem to be required in order to account for the observed smoothness and flatness of our Hubble volume and for the existence of the small primeval density inhomogeneities required for the formation of structure in the Universe. Inflation offers a means of accounting for these special initial data which is based upon physics at sub-planck energy scales ( 19 GeV) and is motivated by contemporary ideas in particle theory. Here I review the status of the 'Inflationary Paradigm,' ''Circa,'' 1986. At present essentially all inflationary models involve a very weakly-coupled (quantified by the presence of a dimensionless parameter of order 10 -12 or so) scalar field which is displaced from the minimum of its potential. Regions of the Universe where the scalar field is initially displaced from its minimum undergo inflation as the scalar field relaxes, resulting in a Universe today which resembles ours in regions much larger than our present Hubble volume (≅10 28 cm), but which on very large scales (>>10 28 cm) may be a highly irregular. At present, the most conspicuous blemish on the paradigm is the lack of a compelling particle physics model to implement it. Some other unresolved issues facing inflation, including the confrontation between inflation and observational data are also reviewed. 112 refs., 4 figs
Inflation in the universe, Circa 1986
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S.
1986-12-01
The hot big bang cosmology, or the standard cosmology as it is appropriately known, is a highly successful model, providing a reliable and tested accounting of the Universe from 0.01 sec after the bang until today, some 15 Gyr later. However, very special initial data seem to be required in order to account for the observed smoothness and flatness of our Hubble volume and for the existence of the small primeval density inhomogeneities required for the formation of structure in the Universe. Inflation offers a means of accounting for these special initial data which is based upon physics at sub-planck energy scales (<
Coopersmith, Michael; Gambardella, Pascal J.
2016-01-01
This article is an extension of the work of one of us (Coopersmith, 2011) in deriving the relationship between certain interest rates and the inflation rate of a two component economic system. We use the well-known Fisher relation between the difference of the nominal interest rate and its inflation adjusted value to eliminate the inflation rate and obtain a delay differential equation. We provide computer simulated solutions for this equation over regimes of interest. This paper could be of ...
Kenneth H. Thomas
2000-01-01
Community Reinvestment Act of 1977 (CRA) ratings and performance evaluations are the only bank and thrift exam findings disclosed by financial institution regulators. Inflation of CRA ratings has been alleged by community activists for two decades, but there has been no quantification or empirical investigation of grade inflation. Using a unique grade inflation methodology on actual ratings and evaluation data for 1,407 small banks and thrifts under the revised CRA regulations, this paper con...
Estimating Venezuelas Latent Inflation
Juan Carlos Bencomo; Hugo J. Montesinos; Hugo M. Montesinos; Jose Roberto Rondo
2011-01-01
Percent variation of the consumer price index (CPI) is the inflation indicator most widely used. This indicator, however, has some drawbacks. In addition to measurement errors of the CPI, there is a problem of incongruence between the definition of inflation as a sustained and generalized increase of prices and the traditional measure associated with the CPI. We use data from 1991 to 2005 to estimate a complementary indicator for Venezuela, the highest inflation country in Latin America. Late...
Topics in Gravitation and Cosmology
Bahrami Taghanaki, Sina
This thesis is focused on two topics in which relativistic gravitational fields play an important role, namely early Universe cosmology and black hole physics. The theory of cosmic inflation has emerged as the most successful theory of the very early Universe with concrete and verifiable predictions for the properties of anisotropies of the cosmic microwave background radiation and large scale structure. Coalescences of black hole binaries have recently been detected by the Laser Interferometer Gravitational Wave Observatory (LIGO), opening a new arena for observationally testing the dynamics of gravity. In part I of this thesis we explore some modifications to the standard theory of inflation. The main predictions of single field slow-roll inflation have been largely consistent with cosmological observations. However, there remain some aspects of the theory that are not presently well understood. Among these are the somewhat interrelated issues of the choice of initial state for perturbations and the potential imprints of pre-inflationary dynamics. It is well known that a key prediction of the standard theory of inflation, namely the Gaussianity of perturbations, is a consequence of choosing a natural vacuum initial state. In chapter 3, we study the generation and detectability of non-Gaussianities in inflationary scalar perturbations that originate from more general choices of initial state. After that, in chapter 4, we study a simple but predictive model of pre-inflationary dynamics in an attempt to test the robustness of inflationary predictions. We find that significant deviations from the standard predictions are unlikely to result from models in which the inflaton field decouples from the pre-inflationary degrees of freedom prior to freeze-out of the observable modes. In part II we turn to a study of an aspect of the thermodynamics of black holes, a subject which has led to important advances in our understanding of quantum gravity. For objects which
Nonminimally coupled hybrid inflation
International Nuclear Information System (INIS)
Koh, Seoktae; Minamitsuji, Masato
2011-01-01
We discuss the hybrid inflation model where the inflaton field is nonminimally coupled to gravity. In the Jordan frame, the potential contains φ 4 term as well as terms in the original hybrid inflation model. In our model, inflation can be classified into the type (I) and the type (II). In the type (I), inflation is terminated by the tachyonic instability of the waterfall field, while in the type (II) by the violation of slow-roll conditions. In our model, the reheating takes place only at the true minimum and even in the case (II) finally the tachyonic instability occurs after the termination of inflation. For a negative nonminimal coupling, inflation takes place in the vacuum-dominated region, in the large field region, or near the local minimum/maximum. Inflation in the vacuum-dominated region becomes either the type (I) or (II), resulting in a blue or red spectrum of the curvature perturbations, respectively. Inflation around the local maximum can be either the type (I) or the type (II), which results in the red spectrum of the curvature perturbations, while around the local minimum it must be the type (I), which results in the blue spectrum. In the large field region, to terminate inflation, potential in the Einstein frame must be positively tilted, always resulting in the red spectrum. We then numerically solve the equations of motion to investigate the whole dynamics of inflaton and confirm that the spectrum of curvature perturbations changes from red to blue ones as scales become smaller.
International Nuclear Information System (INIS)
Vishniac, E.T.
1987-01-01
We examine the compatibility of inflation with the cosmic string theory for galaxy formation. There is a general conflict between having sufficient string tension to effect galaxy formation, and reheating after inflation to a high enough temperature that strings may form in a thermal phase transition. To escape this conflict, we propose a class of models where the inflation is coupled to the string-producing field. The strings are formed late in inflation as the inflaton rolls towards its zero-temperature value. A large subset of these models have a novel large-scale distribution of galaxies that is fractal, displays biasing without dynamics or feedback mechanisms, and contains voids. (orig.)
Quantum fluctuations and inflation
International Nuclear Information System (INIS)
Bardeen, J.M.; Bublik, G.J.
1986-05-01
We study the effect of quantum fluctuations on the roll-down rate of the inflation field in a semiclassical approximation; this is done by treating the inflation field as a classical random field. The quantum fluctuations are simulated by a noise term in the equation of motion. We consider two different inflationary scenarios (new and chaotic inflation) and find that the roll-down rate of the median value of the inflation field is increased by the quantum fluctuations. Non-linear effects may become important in the later stages of the inflationary regime. 8 refs., 2 figs
Quantum fluctuations and inflation
International Nuclear Information System (INIS)
Bardeen, J.M.; Bublik, G.J.
1987-01-01
The authors study the effect of quantum fluctuations on the roll-down rate of the inflation field in a semiclassical approximation; this is done by treating the inflation field as a classical random field. The quantum fluctuations are simulated by a noise term in the equation of motion. Two different inflationary scenarios (new and chaotic inflation) are considered and it is found that the roll-down rate of the median value of the inflation field is increased by the quantum fluctuations. Non-linear effects may become important in the later stages of the inflationary regime. (author)
Inflation Volatility and the Inflation-Growth Tradeoff in India
Raghbendra Jha; Varsha S. Kulkarni
2012-01-01
This paper amends the New Keynesian Phillips curve model to include inflation volatility and tests the determinants of such volatility for India. It provides results on the determinants of inflation volatility and expected inflation volatility for OLS and ARDL (1,1) models and for change in inflation volatility and change in expected inflation volatility using ECM models. Output gap affects change in expected inflation volatility along (in the ECM model) and not in the other models. Major det...
Horizon-preserving dualities and perturbations in non-canonical scalar field cosmologies
International Nuclear Information System (INIS)
Geshnizjani, Ghazal; Kinney, William H.; Dizgah, Azadeh Moradinezhad
2012-01-01
We generalize the cosmological duality between inflation and cyclic contraction under the interchange a↔H to the case of non-canonical scalar field theories with varying speed of sound. The single duality in the canonical case generalizes to a family of three dualities constructed to leave the cosmological acoustic horizon invariant. We find three classes of models: (I) DBI inflation, (II) the non-canonical generalization of cyclic contraction, and (III) a new cosmological solution with rapidly decreasing speed of sound and relatively slowly growing scale factor, which we dub stalled cosmology. We construct dual analogs to the inflationary slow roll approximation, and solve for the curvature perturbation in all three cases. Both cyclic contraction and stalled cosmology predict a strongly blue spectrum for the curvature perturbations inconsistent with observations
Quantum transitions through cosmological singularities
Energy Technology Data Exchange (ETDEWEB)
Bramberger, Sebastian F.; Lehners, Jean-Luc [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), 14476 Potsdam-Golm (Germany); Hertog, Thomas; Vreys, Yannick, E-mail: sebastian.bramberger@aei.mpg.de, E-mail: thomas.hertog@kuleuven.be, E-mail: jlehners@aei.mpg.de, E-mail: yannick.vreys@kuleuven.be [Institute for Theoretical Physics, KU Leuven, 3001 Leuven (Belgium)
2017-07-01
In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.
Quantum transitions through cosmological singularities
International Nuclear Information System (INIS)
Bramberger, Sebastian F.; Lehners, Jean-Luc; Hertog, Thomas; Vreys, Yannick
2017-01-01
In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.
Inflation with non-minimal coupling. Metric vs. Palatini formulations
International Nuclear Information System (INIS)
Bauer, F.; Demir, D.A.; Izmir Institute of Technology
2008-03-01
We analyze non-minimally coupled scalar field theories in metric (second-order) and Palatini (first-order) formalisms in a comparative fashion. After contrasting them in a general setup, we specialize to inflation and find that the two formalisms differ in their predictions for various cosmological parameters. The main reason is that dependencies on the non-minimal coupling parameter are different in the two formalisms. For successful inflation, the Palatini approach prefers a much larger value for the non-minimal coupling parameter than the Metric approach. Unlike the Metric formalism, in Palatini, the inflaton stays well below the Planck scale whereby providing a natural inflationary epoch. (orig.)
Dimensional cosmological principles
International Nuclear Information System (INIS)
Chi, L.K.
1985-01-01
The dimensional cosmological principles proposed by Wesson require that the density, pressure, and mass of cosmological models be functions of the dimensionless variables which are themselves combinations of the gravitational constant, the speed of light, and the spacetime coordinates. The space coordinate is not the comoving coordinate. In this paper, the dimensional cosmological principle and the dimensional perfect cosmological principle are reformulated by using the comoving coordinate. The dimensional perfect cosmological principle is further modified to allow the possibility that mass creation may occur. Self-similar spacetimes are found to be models obeying the new dimensional cosmological principle
Cosmology and particle physics
International Nuclear Information System (INIS)
Turner, M.S.
1985-01-01
The author reviews the standard cosmology, focusing on primordial nucleosynthesis, and discusses how the standard cosmology has been used to place constraints on the properties of various particles. Baryogenesis is examined in which the B, C, CP violating interactions in GUTs provide a dynamical explanation for the predominance of matter over antimatter and the present baryon-to-baryon ratio. Monoposes, cosmology and astrophysics are reviewed. The author also discusses supersymmetry/supergravity and cosmology, superstrings and cosmology in extra dimensions, and axions, astrophics, and cosmology
Energy Technology Data Exchange (ETDEWEB)
Barbour, J B [Department of Physics and Astronomy, University of Rochester (United States)
2007-02-07
the standard model though he has difficulties with X-ray clusters) and the observer Michael Disney, who expresses radical doubts about the concordance model and cites a paper of his (astro-ph/0009020) that is entertaining and hard hitting. But is it worth buying 278 pages for the sake of at most 20? I welcomed the opportunity to review this book since I have stuck my neck out even further than Narlikar and Disney, and this journal has even published an article by me in which I question whether the universe is actually expanding (Classical and Quantum Gravity 20 1571). I wanted to see if there were any chinks in the armour of the standard model. I have to say that having read this book, three modern books on cosmology and attended the recent Cosmic Frontiers conference in Durham (UK), I have to agree with Blanchard when he says: 'When I try to find what the weaknesses of the standard big bang are, I get rather more convinced of its robustness{exclamation_point}' However, I was glad to see that he does not regard inflation as part of the model, and I do think Disney is right to be sceptical about exaggerated claims for the specific concordance model (rather than the basic big-bang idea). However, what I find immensely impressive is how the one simple idea of the expanding universe has proved so fruitful and successful. (book review)
International Nuclear Information System (INIS)
Barbour, J B
2007-01-01
about the concordance model and cites a paper of his (astro-ph/0009020) that is entertaining and hard hitting. But is it worth buying 278 pages for the sake of at most 20? I welcomed the opportunity to review this book since I have stuck my neck out even further than Narlikar and Disney, and this journal has even published an article by me in which I question whether the universe is actually expanding (Classical and Quantum Gravity 20 1571). I wanted to see if there were any chinks in the armour of the standard model. I have to say that having read this book, three modern books on cosmology and attended the recent Cosmic Frontiers conference in Durham (UK), I have to agree with Blanchard when he says: 'When I try to find what the weaknesses of the standard big bang are, I get rather more convinced of its robustness!' However, I was glad to see that he does not regard inflation as part of the model, and I do think Disney is right to be sceptical about exaggerated claims for the specific concordance model (rather than the basic big-bang idea). However, what I find immensely impressive is how the one simple idea of the expanding universe has proved so fruitful and successful. (book review)
Warm inflation with an oscillatory inflaton in the non-minimal kinetic coupling model
International Nuclear Information System (INIS)
Goodarzi, Parviz; Sadjadi, H.M.
2017-01-01
In the cold inflation scenario, the slow roll inflation and reheating via coherent rapid oscillation, are usually considered as two distinct eras. When the slow roll ends, a rapid oscillation phase begins and the inflaton decays to relativistic particles reheating the Universe. In another model dubbed warm inflation, the rapid oscillation phase is suppressed, and we are left with only a slow roll period during which the reheating occurs. Instead, in this paper, we propose a new picture for inflation in which the slow roll era is suppressed and only the rapid oscillation phase exists. Radiation generation during this era is taken into account, so we have warm inflation with an oscillatory inflaton. To provide enough e-folds, we employ the non-minimal derivative coupling model. We study the cosmological perturbations and compute the temperature at the end of warm oscillatory inflation. (orig.)
Warm inflation with an oscillatory inflaton in the non-minimal kinetic coupling model
Energy Technology Data Exchange (ETDEWEB)
Goodarzi, Parviz [University of Ayatollah Ozma Borujerdi, Department of Science, Boroujerd (Iran, Islamic Republic of); Sadjadi, H.M. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of)
2017-07-15
In the cold inflation scenario, the slow roll inflation and reheating via coherent rapid oscillation, are usually considered as two distinct eras. When the slow roll ends, a rapid oscillation phase begins and the inflaton decays to relativistic particles reheating the Universe. In another model dubbed warm inflation, the rapid oscillation phase is suppressed, and we are left with only a slow roll period during which the reheating occurs. Instead, in this paper, we propose a new picture for inflation in which the slow roll era is suppressed and only the rapid oscillation phase exists. Radiation generation during this era is taken into account, so we have warm inflation with an oscillatory inflaton. To provide enough e-folds, we employ the non-minimal derivative coupling model. We study the cosmological perturbations and compute the temperature at the end of warm oscillatory inflation. (orig.)
International Nuclear Information System (INIS)
Mishra, Hiranmaya; Mohanty, Subhendra; Nautiyal, Akhilesh
2013-01-01
In warm inflation models there is the requirement of generating large dissipative couplings of the inflation with radiation, while at the same Âătime, not de-stabilising the flatness of the inflation potential due to radiative corrections. One way to achieve this without fine tuning unrelated couplings is by supersymmetry. In this talk we will discuss warm inflation with Pseudo-Nambu-Goldstone Bosons (PNGB). In this case inflation and other light fields are PNGB. So, the radiative corrections to the potential are suppressed and the thermal Âăcorrections are small as long as the temperature is below the symmetry breaking scale. In such models it is possible to fulfill the contrary requirements of an inflation potential which is stable under radiative corrections and the generation of a large dissipative coupling of the inflation field with other light fields. This warm inflation model with PNGB gives the observed CMB-anisotropy amplitude and spectral index having the symmetry breaking scale at the GUT scale. (author)
Inflation experiences of retirees
Kalwij, Adriaan; Alessie, Robertus; Gardner, Jonathan; Ali, Ashik Anwar
The inflation experience of people depends on their expenditure patterns and price developments. This paper identifies groups of retirees that have experienced relatively high price inflation over the last few decades and could thus be considered most vulnerable when income decreases, as has been
Air-Inflated Fabric Structures
National Research Council Canada - National Science Library
Cavallaro, Paul V; Sadegh, Ali M
2006-01-01
.... Examples include air ships, weather balloons, inflatable antennas and radomes, temporary shelters, pneumatic muscles and actuators, inflatable boats, temporary bridging, and energy absorbers such as automotive air bags...
Cosmological special relativity the large scale structure of space, time and velocity
Carmeli, Moshe
1997-01-01
This book deals with special relativity theory and its application to cosmology. It presents Einstein's theory of space and time in detail, and describes the large scale structure of space, time and velocity as a new cosmological special relativity. A cosmological Lorentz-like transformation, which relates events at different cosmic times, is derived and applied. A new law of addition of cosmic times is obtained, and the inflation of the space at the early universe is derived, both from the cosmological transformation. The book will be of interest to cosmologists, astrophysicists, theoretical
Cosmological special relativity the large scale structure of space, time and velocity
Carmeli, Moshe
2002-01-01
This book presents Einstein's theory of space and time in detail, and describes the large-scale structure of space, time and velocity as a new cosmological special relativity. A cosmological Lorentz-like transformation, which relates events at different cosmic times, is derived and applied. A new law of addition of cosmic times is obtained, and the inflation of the space at the early universe is derived, both from the cosmological transformation. The relationship between cosmic velocity, acceleration and distances is given. In the appendices gravitation is added in the form of a cosmological g
Axion excursions of the landscape during inflation
Palma, Gonzalo A.; Riquelme, Walter
2017-07-01
Because of their quantum fluctuations, axion fields had a chance to experience field excursions traversing many minima of their potentials during inflation. We study this situation by analyzing the dynamics of an axion field ψ , present during inflation, with a periodic potential given by v (ψ )=Λ4[1 -cos (ψ /f )]. By assuming that the vacuum expectation value of the field is stabilized at one of its minima, say, ψ =0 , we compute every n -point correlation function of ψ up to first order in Λ4 using the in-in formalism. This computation allows us to identify the distribution function describing the probability of measuring ψ at a particular amplitude during inflation. Because ψ is able to tunnel between the barriers of the potential, we find that the probability distribution function consists of a non-Gaussian multimodal distribution such that the probability of measuring ψ at a minimum of v (ψ ) different from ψ =0 increases with time. As a result, at the end of inflation, different patches of the Universe are characterized by different values of the axion field amplitude, leading to important cosmological phenomenology: (a) Isocurvature fluctuations induced by the axion at the end of inflation could be highly non-Gaussian. (b) If the axion defines the strength of standard model couplings, then one is led to a concrete realization of the multiverse. (c) If the axion corresponds to dark matter, one is led to the possibility that, within our observable Universe, dark matter started with a nontrivial initial condition, implying novel signatures for future surveys.
International Nuclear Information System (INIS)
Gaisser, T.K.; Shafi, Q.; Barr, S.M.; Seckel, D.; Rusjan, E.; Fletcher, R.S.
1991-01-01
This report discusses research of professor at Bartol research institute in the following general areas: particle phenomenology and non-accelerator physics; particle physics and cosmology; theories with higher symmetry; and particle astrophysics and cosmology
International Nuclear Information System (INIS)
Heller, M.
1985-01-01
Two Friedman's cosmological papers (1922, 1924) and his own interpretation of the obtained results are briefly reviewed. Discussion follows of Friedman's role in the early development of relativistic cosmology. 18 refs. (author)
Kunze, Kerstin E.
2016-12-20
Cosmology is becoming an important tool to test particle physics models. We provide an overview of the standard model of cosmology with an emphasis on the observations relevant for testing fundamental physics.
Frame-Covariant Formulation of Inflation in Scalar-Curvature Theories
Burns, Daniel; Pilaftsis, Apostolos
2016-01-01
We develop a frame-covariant formulation of inflation in the slow-roll approximation by generalizing the inflationary attractor solution for scalar-curvature theories. Our formulation gives rise to new generalized forms for the potential slow-roll parameters, which enable us to examine the effect of conformal transformations and inflaton reparameterizations in scalar-curvature theories. We find that cosmological observables, such as the power spectrum, the spectral indices and their runnings, can be expressed in a concise manner in terms of the generalized potential slow-roll parameters which depend on the scalar-curvature coupling function, the inflaton wavefunction, and the inflaton potential. We show how the cosmological observables of inflation are frame-invariant in this generalized potential slow-roll formalism, as long as the end-of-inflation condition is appropriately extended to become frame-invariant as well. We then apply our formalism to specific scenarios, such as the induced gravity inflation, H...
Magnon inflation: slow roll with steep potentials
Energy Technology Data Exchange (ETDEWEB)
Adshead, Peter [Department of Physics, University of Illinois at Urbana-Champaign,Urbana, IL 61801 (United States); Blas, Diego [Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); Burgess, C.P.; Hayman, Peter [Physics & Astronomy, McMaster University,Hamilton, ON, L8S 4M1 (Canada); Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada); Patil, Subodh P. [Department of Theoretical Physics, University of Geneva,24 Quai Ansermet, Geneva, CH-1211 (Switzerland)
2016-11-04
We find multi-scalar effective field theories (EFTs) that can achieve a slow inflationary roll despite having a scalar potential that does not satisfy G{sup ab}∂{sub a}V∂{sub b}V≪V{sup 2}/M{sub p}{sup 2} (where G{sub ab} is the target-space metric). They evade the usual slow-roll conditions on V because their kinetic energies are dominated by single-derivative terms rather than the usual two-derivative terms. Single derivatives dominate during slow roll and so do not require a breakdown of the usual derivative expansion that underpins calculational control in much of cosmology. The presence of such terms requires some sort of UV Lorentz-symmetry breaking during inflation (besides the usual cosmological breaking). Chromo-natural inflation provides one particular example of a UV theory that can generate the multi-field single-derivative terms we consider, and we argue that the EFT we find indeed captures the slow-roll conditions for its background evolution. We also show that our EFT can be understood as a multi-field generalization of the single-field Cuscuton models. The multi-field case introduces a new feature, however: the scalar kinetic terms define a target-space 2-form, F{sub ab}, whose antisymmetry gives new ways for slow roll to be achieved.
Roos, Matts
2015-01-01
The Fourth Edition of Introduction to Cosmology provides a concise, authoritative study of cosmology at an introductory level. Starting from elementary principles and the early history of cosmology, the text carefully guides the student on to curved spacetimes, special and general relativity, gravitational lensing, the thermal history of the Universe, and cosmological models, including extended gravity models, black holes and Hawking's recent conjectures on the not-so-black holes.
Particle physics and cosmology
International Nuclear Information System (INIS)
Turner, M.S.; Schramm, D.N.
1985-01-01
During the past year, the research of the members of our group has spanned virtually all the topics at the interface of cosmology and particle physics: inflationary Universe scenarios, astrophysical and cosmological constraints on particle properties, ultra-high energy cosmic ray physics, quantum field theory in curved space-time, cosmology with extra dimensions, superstring cosmology, neutrino astronomy with large, underground detectors, and the formation of structure in the Universe
Brane inflation: A field theory approach in background supergravity
International Nuclear Information System (INIS)
Choudhury, Sayantan; Pal, Supratik
2012-01-01
We propose a model of inflation in the framework of brane cosmology driven by background supergravity. Starting from bulk supergravity we construct the inflaton potential on the brane and employ it to investigate for the consequences to inflationary paradigm. To this end, we derive the expressions for the important parameters in brane inflation, which are somewhat different from their counterparts in standard cosmology, using the one loop radiative corrected potential. We further estimate the observable parameters and find them to fit well with recent observational data. We have studied extensively reheating phenomenology, which explains the thermal history of the universe and leptogenesis through the production of thermal gravitino pertaining to the particle physics phenomenology of the early universe.
The inflation sector of extended inflation
International Nuclear Information System (INIS)
Kolb, E.W.
1990-11-01
In extended inflation the inflationary era is brought to a close by the process of percolation of true vacuum bubbles produced in a first-order phase transition. In this paper I discuss several effects that might obtain if the Universe undergoes an inflationary first-order phase transition. 17 refs
Phantom cosmologies and fermions
International Nuclear Information System (INIS)
Chimento, Luis P; Forte, Monica; Devecchi, Fernando P; Kremer, Gilberto M
2008-01-01
Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the 'phantomization' process exhibits a new class of possible accelerated regimes. As an application we analyze the cosmological constant group for a fermionic seed fluid
Particle physics and cosmology
International Nuclear Information System (INIS)
Schramm, D.N.; Turner, M.S.
1982-06-01
work is described in these areas: cosmological baryon production; cosmological production of free quarks and other exotic particle species; the quark-hadron transition in the early universe; astrophysical and cosmological constraints on particle properties; massive neutrinos; phase transitions in the early universe; and astrophysical implications of an axion-like particle
International Nuclear Information System (INIS)
Weinberg, S.
1989-01-01
Cosmological constant problem is discussed. History of the problem is briefly considered. Five different approaches to solution of the problem are described: supersymmetry, supergravity, superstring; anthropic approach; mechamism of lagrangian alignment; modification of gravitation theory and quantum cosmology. It is noted that approach, based on quantum cosmology is the most promising one
. ______________________________________________________________________________________ Nobelist George Smoot to Direct Korean Cosmology Institute Nobel Laureate George Smoot has been appointed director of a new cosmology institute in South Korea that will work closely with the year-old Berkeley the Early Universe (IEU) at EWHA Womans University in Seoul, Korea will provide cosmology education
International Nuclear Information System (INIS)
Davies, P.
1991-01-01
The main concepts of cosmology are discussed, and some of the misconceptions are clarified. The features of big bang cosmology are examined, and it is noted that the existence of the cosmic background radiation provides welcome confirmation of the big bang theory. Calculations of relative abundances of the elements conform with observations, further strengthening the confidence in the basic ideas of big bang cosmology
CERN. Geneva. Audiovisual Unit
2001-01-01
Cosmology and particle physics have enjoyed a useful relationship over the entire histories of both subjects. Today, ideas and techniques in cosmology are frequently used to elucidate and constrain theories of elementary particles. These lectures give an elementary overview of the essential elements of cosmology, which is necessary to understand this relationship.
CERN. Geneva
1999-01-01
Cosmology and particle physics have enjoyed a useful relationship over the entire histories of both subjects. Today, ideas and techniques in cosmology are frequently used to elucidate and constrain theories of elementary particles. These lectures give an elementary overview of the essential elements of cosmology, which is necessary to understand this relationship.
International Nuclear Information System (INIS)
Langer, M.
2007-01-01
This is a very concise introductory lecture to Cosmology. We start by reviewing the basics of homogeneous and isotropic cosmology. We then spend some time on the description of the Cosmic Microwave Background. Finally, a small section is devoted to the discussion of the cosmological constant and of some of the related problems
Inflation perceptions and inflation expectation in South Africa: trends ...
African Journals Online (AJOL)
This paper reports the results of a multinomial analysis of inflation perceptions and inflation expectations in South Africa. Inflation perceptions surveys among South African individuals have been undertaken since 2006. The introduction of these surveys followed on domestic inflation expectation surveys conducted in 2000, ...
Starobinsky-like inflation and neutrino masses in a no-scale SO(10) model
Energy Technology Data Exchange (ETDEWEB)
Ellis, John [Theoretical Particle Physics and Cosmology Group,Department of Physics, King’s College London, WC2R 2LS London (United Kingdom); Theoretical Physics Department, CERN,CH-1211 Geneva 23 (Switzerland); Garcia, Marcos A.G. [Physics and Astronomy Department, Rice University,6100 Main Street, Houston, TX 77005 (United States); Nagata, Natsumi [Department of Physics, University of Tokyo,Bunkyo-ku, Tokyo 113-0033 (Japan); Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University, College Station, 77843 Texas (United States); Olive, Keith A. [William I. Fine Theoretical Physics Institute, School of Physics and Astronomy, University of Minnesota,116 Church Street SE, Minneapolis, MN 55455 (United States)
2016-11-08
Using a no-scale supergravity framework, we construct an SO(10) model that makes predictions for cosmic microwave background observables similar to those of the Starobinsky model of inflation, and incorporates a double-seesaw model for neutrino masses consistent with oscillation experiments and late-time cosmology. We pay particular attention to the behaviour of the scalar fields during inflation and the subsequent reheating.
Starobinsky-Like Inflation and Neutrino Masses in a No-Scale SO(10) Model
Ellis, John
2016-11-08
Using a no-scale supergravity framework, we construct an SO(10) model that makes predictions for cosmic microwave background observables similar to those of the Starobinsky model of inflation, and incorporates a double-seesaw model for neutrino masses consistent with oscillation experiments and late-time cosmology. We pay particular attention to the behaviour of the scalar fields during inflation and the subsequent reheating.
International Nuclear Information System (INIS)
Desroche, Mariel; Felder, Gary N.; Kratochvil, Jan M.; Linde, Andrei
2005-01-01
During the last ten years a detailed investigation of preheating was performed for chaotic inflation and for hybrid inflation. However, nonperturbative effects during reheating in the new inflation scenario remained practically unexplored. We investigate preheating in new inflation, using a combination of analytical and numerical methods. We find that the decay of the homogeneous component of the inflaton field and the resulting process of spontaneous symmetry breaking in the simplest models of new inflation usually occurs almost instantly: for the new inflation on the GUT scale it takes only about 5 oscillations of the field distribution. The decay of the homogeneous inflaton field is so efficient because of a combined effect of tachyonic preheating and parametric resonance. At that stage, the homogeneous oscillating inflaton field decays into a collection of waves of the inflaton field, with a typical wavelength of the order of the inverse inflaton mass. This stage usually is followed by a long stage of decay of the inflaton field into other particles, which can be described by the perturbative approach to reheating after inflation. The resulting reheating temperature typically is rather low
Inflation, inflation uncertainty and output growth in the USA
Bhar, Ramprasad; Mallik, Girijasankar
2010-12-01
Employing a multivariate EGARCH-M model, this study investigates the effects of inflation uncertainty and growth uncertainty on inflation and output growth in the United States. Our results show that inflation uncertainty has a positive and significant effect on the level of inflation and a negative and significant effect on the output growth. However, output uncertainty has no significant effect on output growth or inflation. The oil price also has a positive and significant effect on inflation. These findings are robust and have been corroborated by use of an impulse response function. These results have important implications for inflation-targeting monetary policy, and the aim of stabilization policy in general.
Primordial large-scale electromagnetic fields from gravitoelectromagnetic inflation
Energy Technology Data Exchange (ETDEWEB)
Membiela, Federico Agustin [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, (7600) Mar del Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)], E-mail: membiela@mdp.edu.ar; Bellini, Mauricio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, (7600) Mar del Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)], E-mail: mbellini@mdp.edu.ar
2009-04-20
We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant {lambda}{sub 0}. Using the gravitoelectromagnetic inflationary formalism with A{sub 0}=0, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is naturally non-conformally invariant.
Primordial large-scale electromagnetic fields from gravitoelectromagnetic inflation
Membiela, Federico Agustín; Bellini, Mauricio
2009-04-01
We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant Λ0. Using the gravitoelectromagnetic inflationary formalism with A0 = 0, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is naturally non-conformally invariant.
Primordial large-scale electromagnetic fields from gravitoelectromagnetic inflation
International Nuclear Information System (INIS)
Membiela, Federico Agustin; Bellini, Mauricio
2009-01-01
We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant Λ 0 . Using the gravitoelectromagnetic inflationary formalism with A 0 =0, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is naturally non-conformally invariant.
International Nuclear Information System (INIS)
Davis, R.L.; Shellard, E.P.S.; Massachusetts Inst. of Tech., Cambridge
1989-01-01
Without inflation the energy density of relic axions in a Robertson-Walker universe arises not from coherent oscillations of a zero-momentum mode but from radiative decay of axion strings. An estimate of the upper bound on the PQ scale coming from these axions is in conflict with the lower bound from SN1987a. We present analytical and numerical evidence supporting this estimate. If true, then the axion needs inflation. With inflation the axion is safe, but the motivation for axion search experiments is weakened. (orig.)