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On hilltop and brane inflation after PlanckJun 05 2019Hilltop inflation models are often described by potentials $V = V_{0}(1-{\phi^{n}\over m^{n}}+...)$. The omitted terms indicated by ellipsis do not affect inflation for $m \lesssim 1$, but the most popular models with $n =2$ and $4$ for $m \lesssim 1$ ... More

Topological Defects as Seeds for Eternal InflationFeb 20 1994We investigate the global structure of inflationary universe both by analytical methods and by computer simulations of stochastic processes in the early Universe. We show that the global structure of the universe depends crucially on the mechanism of ... More

Progress in the Theory of the Electroweak Phase TransitionJun 29 1992Recent progress in the theory of the electroweak phase transition is discussed. For the Higgs boson mass smaller than the masses of W and Z bosons, the phase transition is of the first order. However, its strength is approximately 2/3 times less than ... More

Relaxing the Cosmological Moduli ProblemJan 16 1996Typically the moduli fields acquire mass m =C H in the early universe, which shifts the position of the minimum of their effective potential and leads to an excessively large energy density of the oscillating moduli fields at the later stages of the evolution ... More

Fast-Roll InflationOct 21 2001Oct 26 2001We show that in the simplest theories of spontaneous symmetry breaking one can have a stage of a fast-roll inflation. In this regime the standard slow-roll condition |m^2| << H^2 is violated. Nevertheless, this stage can be rather long if |m| is sufficiently ... More

Inflation and String CosmologyMar 24 2005After 25 years of its existence, inflationary theory gradually becomes the standard cosmological paradigm. However, we still do not know which of the many versions of inflationary cosmology will be favored by the future observational data. Moreover, it ... More

Creation of a Compact Topologically Nontrivial Inflationary UniverseAug 23 2004Sep 11 2004If inflation can occur only at the energy density V much smaller than the Planck density, which is the case for many inflationary models based on string theory, then the probability of quantum creation of a closed or an infinitely large open inflationary ... More

Random Potentials and Cosmological AttractorsDec 14 2016Jan 03 2017I show that the problem of realizing inflation in theories with random potentials of a limited number of fields can be solved, and agreement with the observational data can be naturally achieved if at least one of these fields has a non-minimal kinetic ... More

Lectures on Inflationary CosmologyOct 12 1994A general overview of the history and present status of inflationary cosmology is given. Recent developments discussed in this paper include the hybrid inflation scenario, the theory of reheating, and the theory of inflating tolopogical defects. We also ... More

Inflation, Quantum Cosmology and the Anthropic PrincipleNov 07 2002Nov 08 2002Anthropic principle can help us to understand many properties of our world. However, for a long time this principle seemed too metaphysical and many scientists were ashamed to use it in their research. I describe here a justification of the weak anthropic ... More

Inflation and String CosmologyJul 20 2001Inflationary theory is already 20 years old, and it is impossible to describe all of its versions and implications in a short talk. I will concentrate on several subjects which I believe to be most important. First of all, I will give a brief review of ... More

Gravitational waves and large field inflationNov 30 2016According to the famous Lyth bound, one can confirm large field inflation by finding tensor modes with sufficiently large tensor-to-scalar ratio $r$. Here we will try to answer two related questions: Is it possible to rule out all large field inflationary ... More

A brief history of the multiverseDec 03 2015The theory of the inflationary multiverse changes the way we think about our place in the world. According to its most popular version, our world may consist of infinitely many exponentially large parts, exhibiting different sets of low-energy laws of ... More

On inflation, cosmological constant, and SUSY breakingJul 30 2016Aug 22 2016We consider a broad class of inflationary models of two unconstrained chiral superfields, the stabilizer $S$ and the inflaton $\Phi$, which can describe inflationary models with nearly arbitrary potentials. These models include, in particular, the recently ... More

Particle Physics and Inflationary CosmologyMar 26 2005This 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. ... More

Prospects of InflationFeb 06 2004Feb 15 2004I will discuss the development of inflationary theory and its present status, including recent progress in describing de Sitter space and inflationary universe in string theory.

Strings, Textures, Inflation and Spectrum BendingMar 16 1992We discuss relationship between inflation and various models of production of density inhomogeneities due to strings, global monopoles, textures and other topological and non-topological defects. Neither of these models leads to a consistent cosmological ... More

Can we have inflation with Omega > 1?Mar 12 2003Apr 01 2003It is very difficult to obtain a realistic model of a closed inflationary universe. Even if one fine-tunes the total number of e-folds to be sufficiently small, the resulting universe typically has large density perturbations on the scale of the horizon. ... More

Prospects of Inflationary CosmologyOct 10 1996In this review I briefly describe the evolution of the inflationary theory from the scenario based on the idea of supercooling and expansion in the false vacuum toward the theory of eternally expanding self-reproducing inflationary universe. I describe ... More

INFLATION WITH VARIABLE OMEGAMar 15 1995Apr 07 1995We propose a simple version of chaotic inflation scenario which leads to a division of the universe into infinitely many open universes with all possible values of $\Omega$ from 1 to 0.

Comments on Inflationary CosmologySep 28 1993In this talk we discuss three different issues. First of all, there exist several proposals how to solve cosmological problems by adiabatic expansion of the Universe, without any use of inflation. We explain why these models do not solve the flatness/entropy ... More

On inflation, cosmological constant, and SUSY breakingJul 30 2016Oct 27 2016We consider a broad class of inflationary models of two unconstrained chiral superfields, the stabilizer $S$ and the inflaton $\Phi$, which can describe inflationary models with nearly arbitrary potentials. These models include, in particular, the recently ... More

On the problem of initial conditions for inflationOct 11 2017Mar 27 2018I review the present status of the problem of initial conditions for inflation and describe several ways to solve this problem for many popular inflationary models, including the recent generation of the models with plateau potentials favored by cosmological ... More

Sinks in the Landscape, Boltzmann Brains, and the Cosmological Constant ProblemNov 06 2006Jan 28 2007This paper extends the recent investigation of the string theory landscape in hep-th/0605266, where it was found that the decay rate of dS vacua to a collapsing space with a negative vacuum energy can be quite large. The parts of space that experience ... More

Towards a gauge invariant volume-weighted probability measure for eternal inflationMay 08 2007May 20 2007An improved volume-weighted probability measure for eternal inflation is proposed. For the models studied in this paper it leads to simple and intuitively expected gauge-invariant results.

Quantum Creation of an Open Inflationary UniverseFeb 17 1998May 25 1998We discuss a dramatic difference between the description of the quantum creation of an open universe using the Hartle-Hawking wave function and the tunneling wave function. Recently Hawking and Turok have found that the Hartle-Hawking wave function leads ... More

Monopoles as Big as a UniverseFeb 11 1994We show that, contrary to the standard belief, primordial monopoles expand exponentially during inflation in the new inflationary universe scenario. Moreover, inflation of monopoles continues without an end even when inflation ends in the surrounding ... More

Does the first chaotic inflation model in supergravity provide the best fit to the Planck data?Dec 22 2014Jan 17 2015I describe the first model of chaotic inflation in supergravity, which was proposed by Goncharov and the present author in 1983. The inflaton potential of this model has a plateau-type behavior $V_{0} (1- {8\over 3}\, e^{-\sqrt 6 |\phi|})$ at large values ... More

Chaotic inflation in supergravity and cosmic string productionMar 18 2013We describe a simple model of chaotic inflation in supergravity where one can easily tune not only the basic cosmological parameters such as n_{s}, r, and f_NL, but also a possible (subdominant) cosmic string contribution to the CMB anisotropy.

Inflationary CosmologyMay 02 2007May 16 2007I give a general review of the history of inflationary cosmology and of its present status.

Recent Progress in Inflationary CosmologyJan 02 1996We discuss two important modifications of inflationary paradigm. Until very recently we believed that inflation automatically leads to flatness of the universe, Omega = 1. We also thought that post-inflationary phase transitions in GUTs may occur only ... More

Quantum Cosmology and the Structure of Inflationary UniverseAug 08 1995In this review I consider several different issues related to inflation. I will begin with the wave function of the Universe. This issue is pretty old, but recently there were some new insights based on the theory of the self-reproducing inflationary ... More

Inflationary Theory versus Ekpyrotic/Cyclic ScenarioMay 26 2002I will discuss the development of inflationary theory and its present status, as well as some recent attempts to suggest an alternative to inflation. In particular, I will argue that the ekpyrotic scenario in its original form does not solve any of the ... More

A Toy Model for Open InflationJul 27 1998Aug 14 1998The open inflation scenario based on the theory of bubble formation in the models of a single scalar field suffered from a fatal defect. In all the versions of this scenario known so far, the Coleman-De Luccia instantons describing the creation of an ... More

Hybrid InflationJul 01 1993Sep 27 1993Usually inflation ends either by a slow rolling of the inflaton field, which gradually becomes faster and faster, or by a first-order phase transition. We describe a model where inflation ends in a different way, due to a very rapid rolling (`waterfall') ... More

Hard Art of the Universe CreationOct 15 1991We develop a stochastic approach to the theory of tunneling with the baby universe formation. This method is applied also to the theory of creation of the universe in a laboratory.

Single-field $α$-attractorsApr 02 2015I describe a simple class of $\alpha$-attractors, generalizing the single-field GL model of inflation in supergravity. The new class of models is defined for $0<\alpha \lesssim 1$, providing a good match to the present cosmological data. I also present ... More

Inflationary Cosmology after Planck 2013Feb 03 2014Mar 09 2014I give a general review of inflationary cosmology and of its present status, in view of the 2013 data release by the Planck satellite. A specific emphasis is given to the new broad class of theories, the cosmological attractors, which have nearly model-independent ... More

Inflation and Large Internal DimensionsNov 16 1998Dec 12 1998We consider some aspects of inflation in models with large internal dimensions. If inflation occurs on a 3D wall after the stabilization of internal dimensions in the models with low unification scale (M ~ 1 TeV), the inflaton field must be extremely ... More

Quantum Creation of a Universe with $Ω\not = 1$: Singular and Non-Singular InstantonsMar 19 1998Apr 14 1998We propose two new classes of instantons which describe the tunneling and/or quantum creation of closed and open universes. The instantons leading to an open universe can be considered as generalizations of the Coleman-De-Luccia solution. They are non-singular, ... More

How many universes are in the multiverse?Oct 09 2009Apr 01 2010We argue that the total number of distinguishable locally Friedmann universes generated by eternal inflation is proportional to the exponent of the entropy of inflationary perturbations and is limited by e^{e^{3 N}}, where N is the number of e-folds of ... More

Problems with Tachyon InflationMay 14 2002We consider cosmological consequences of string theory tachyon condensation. We show that it is very difficult to obtain inflation in the simplest versions of this theory. Typically, inflation in these theories could occur only at super-Planckian densities, ... More

The Curvaton WebNov 28 2005Mar 13 2006We discuss nontrivial features of the large scale structure of the universe in the simplest curvaton model proposed in our paper astro-ph/9610219. The amplitude of metric perturbations in this model takes different values in different parts of the universe. ... More

Stationary UniverseApr 13 1993May 13 1993If the Universe contains at least one inflationary domain with a sufficiently large and homogeneous scalar field, then this domain permanently produces new inflationary domains of all possible types. We show that under certain conditions this process ... More

Escher in the SkyMar 23 2015May 05 2015The cosmological models called $\alpha$-attractors provide an excellent fit to the latest observational data. Their predictions $n_{s} = 1-2/N$ and $r = 12\alpha/N^{2}$ are very robust with respect to the modifications of the inflaton potential. An intriguing ... More

Hidden Superconformal Symmetry of the Cosmological EvolutionNov 13 2013Jan 08 2014In the superconformal formulation of supergravity, the standard supergravity action appears as a result of spontaneous symmetry breaking when the conformal compensator scalar field, the conformon, acquires a nonzero value, giving rise to the Planck mass. ... More

Multi-field Conformal Cosmological AttractorsSep 08 2013We describe a broad class of multi-field inflationary models with spontaneously broken conformal invariance. It generalizes the recently discovered class of cosmological attractors with a single inflaton field. In the new multi-field theories, just as ... More

P-term, D-term and F-term inflationJun 09 2003Sep 30 2003P-term inflation is a version of hybrid inflation which naturally appears in some brane inflation models. It was introduced in the framework of N=2 supersymmetric gauge theory where superconformal SU(2,2|2) symmetry is broken down to N=2 supersymmetry ... More

Dark Energy and the Fate of the UniverseJan 06 2003Jan 22 2003It is often assumed that in the course of the evolution of the universe, the dark energy either vanishes or becomes a positive constant. However, recently it was shown that in many models based on supergravity, the dark energy eventually becomes negative ... More

Supersymmetric Balance of Forces and Condensation of BPS StatesNov 16 1995Until now all known static multi black hole solutions described BPS states with charges of the same sign. Such solutions could not be related to flat directions in the space of BPS states. The total number of such states could not spontaneously increase ... More

Strong moduli stabilization and phenomenologySep 03 2012Jan 15 2013We describe the resulting phenomenology of string theory/supergravity models with strong moduli stabilization. The KL model with F-term uplifting, is one such example. Models of this type predict universal scalar masses equal to the gravitino mass. In ... More

Inflation with $Ω\not = 1$Jun 03 1995Aug 03 1995We discuss various models of inflationary universe with $\Omega \not = 1$. A homogeneous universe with $\Omega > 1$ may appear due to creation of the universe "from nothing" in the theories where the effective potential becomes very steep at large $\phi$, ... More

Hybrid Inflation in SupergravityMar 02 1997Mar 14 1997We propose a simple realization of hybrid inflation in supergravity, which does not require any unnaturally small parameters. Inflation in this scenario is relatively short, and inflationary density perturbations fall down on large scales, which corresponds ... More

Non-minimal Inflationary AttractorsJul 30 2013Sep 08 2013Recently we identified a new class of (super)conformally invariant theories which allow inflation even if the scalar potential is very steep in terms of the original conformal variables. Observational predictions of a broad class of such theories are ... More

O'KKLTNov 16 2006Jan 28 2007We propose to combine the quantum corrected O'Raifeartaigh model, which has a dS minimum near the origin of the moduli space, with the KKLT model with an AdS minimum. The combined effective N=1 supergravity model, which we call O'KKLT, has a dS minimum ... More

Exact Supersymmetric Massive and Massless White HolesJul 05 1995Oct 10 1995We study special points in the moduli space of vacua at which supersymmetric electric solutions of the heterotic string theory become massless. We concentrate on configurations for which supersymmetric non-renormalization theorem is valid. Those are ten-dimensional ... More

Towards a non-anthropic solution to the cosmological constant problemOct 31 2010Many probability measures in the multiverse depend exponentially on some observable parameters, giving rise to potential problems such as youngness bias, Q-catastrophe etc. In this paper we explore a possibility that the exponential runaway dependence ... More

Measure Problem for Eternal and Non-Eternal InflationJun 10 2010Aug 11 2010We study various probability measures for eternal inflation by applying their regularization prescriptions to models where inflation is not eternal. For simplicity we work with a toy model describing inflation that can interpolate between eternal and ... More

Cosmology vs. HolographyApr 19 1999Jul 01 1999The most radical version of the holographic principle asserts that all information about physical processes in the world can be stored on its surface. This formulation is at odds with inflationary cosmology, which implies that physical processes in our ... More

Inflation and Uplifting with Nilpotent SuperfieldsAug 25 2014Nov 26 2014Recently it was found that a broad class of existing inflationary models based on supergravity can be significantly simplified if some of the standard, unconstrained chiral superfields are replaced by nilpotent superfields, associated with Volkov-Akulov ... More

Universality Class in Conformal InflationJun 21 2013Sep 08 2013We develop a new class of chaotic inflation models with spontaneously broken conformal invariance. Observational consequences of a broad class of such models are stable with respect to strong deformations of the scalar potential. This universality is ... More

Superconformal generalizations of the Starobinsky modelJun 13 2013Jun 19 2013We find a way to represent the Starobinsky model in terms of a simple conformally invariant theory with spontaneous symmetry breaking. We also present a superconformal theory, which, upon spontaneous breaking of the superconformal symmetry, provides a ... More

Testing String Theory with CMBApr 05 2007Future detection/non-detection of tensor modes from inflation in CMB observations presents a unique way to test certain features of string theory. Current limit on the ratio of tensor to scalar perturbations, r=T/S, is r < 0.3, future detection may take ... More

Supersymmetry and the Brane WorldJan 11 2000Feb 07 2000We investigate the possibility of gravity localization on the brane in the context of supersymmetric theories. To realize this scenario one needs to find a theory with the supersymmetric flow stable in IR at two critical points, one with positive and ... More

M-theory, Cosmological Constant and Anthropic PrincipleAug 21 2002Nov 08 2002We discuss the theory of dark energy based on maximally extended supergravity and suggest a possible anthropic explanation of the present value of the cosmological constant and of the observed ratio between dark energy and energy of matter.

Black Hole Superpartners and Fixed ScalarsNov 21 1996Some bosonic solutions of supergravities admit Killing spinors of unbroken supersymmetry. The anti-Killing spinors of broken supersymmetry can be used to generate the superpartners of stringy black holes. This has a consequent feedback on the metric and ... More

Accidental Inflation in String TheoryDec 11 2007We show that inflation in type IIB string theory driven by the volume modulus can be realized in the context of the racetrack-based Kallosh-Linde model (KL) of moduli stabilization. Inflation here arises through the volume modulus slow-rolling down from ... More

B-mode TargetsJun 11 2019The CMB-S4 Science Book, Astro2020 Science White Paper on gravitational waves, and PICO report contain an extensive discussion of many ongoing and planned efforts in the search for gravitational waved produced by inflation. Here we give a short executive ... More

On Regularization Scheme Dependence of Predictions in Inflationary CosmologyNov 22 1995We show that there exists a large class of regularization schemes for probabilistic predictions in the theory of a self-reproducing inflationary univere, all of which eliminate the apparent dependence on the time reparametrization. However, all these ... More

Cosmological Attractors and Asymptotic Freedom of the Inflaton FieldApr 02 2016Jun 24 2016We show that the inflaton coupling to all other fields is exponentially suppressed during inflation in the cosmological $\alpha$-attractor models. In the context of supergravity, this feature is a consequence of the underlying hyperbolic geometry of the ... More

Planck, LHC, and $α$-attractorsFeb 26 2015Apr 08 2015We describe a simple class of cosmological models called $\alpha$ attractors, which provide an excellent fit to the latest Planck data. These theories are most naturally formulated in the context of supergravity with logarithmic Kahler potentials. We ... More

New models of chaotic inflation in supergravityAug 19 2010Sep 13 2010We introduce a new class of models of chaotic inflation inspired by the superconformal approach to supergravity. This class of models allows a functional freedom of choice of the inflaton potential V = |f(\phi)|^2. The simplest model of this type has ... More

Superconformal Generalization of the Chaotic Inflation Model λ φ^4/4 - ξ/ 2 φ^2 RJun 13 2013Jun 19 2013A model of chaotic inflation based on the theory of a scalar field with potential \lambda\phi^4 perfectly matches the observational data if one adds to it a tiny non-minimal coupling to gravity -\xi/2 \phi^2 R with \xi > 0.002. We describe embedding of ... More

Strings, Black Holes, and Quantum InformationFeb 07 2006May 04 2006We find multiple relations between extremal black holes in string theory and 2- and 3-qubit systems in quantum information theory. We show that the entropy of the axion-dilaton extremal black hole is related to the concurrence of a 2-qubit state, whereas ... More

Landscape, the Scale of SUSY Breaking, and InflationNov 01 2004Jan 29 2005We argue that in the simplest version of the KKLT model, the maximal value of the Hubble constant during inflation cannot exceed the present value of the gravitino mass, H< m_{3/2}. This may have important implications for string cosmology and for the ... More

Fluctuations of the Gravitational Constant in the Inflationary Brans-Dicke CosmologyDec 16 1993Jun 07 2006According to the Brans--Dicke theory, the value of the gravitational constant G which we measure at present is determined by the value of the Brans--Dicke scalar field \phi at the end of inflation. However, due to quantum fluctuations of the scalar fields ... More

Do We Live in the Center of the World?Nov 16 1994We investigate the distribution of energy density in a stationary self-reproducing inflationary universe. We show that the main fraction of volume of the universe in a state with a given density $\rho$ at any given moment of time $t$ in synchronous coordinates ... More

From the Big Bang Theory to the Theory of a Stationary UniverseJun 29 1993Feb 01 2006We consider chaotic inflation in the theories with the effective potentials phi^n and e^{\alpha\phi}. In such theories inflationary domains containing sufficiently large and homogeneous scalar field \phi permanently produce new inflationary domains of ... More

Nonperturbative Amplifications of Inhomogeneities in a Self-Reproducing UniverseJan 03 1996We investigate the distribution of energy density in a stationary self-reproducing inflationary universe. We show that the main fraction of volume of the universe in a state with a given density at any given moment of proper time t is concentrated near ... More

Preheating in Hybrid InflationNov 18 1997Dec 21 1997We investigate the possibility of preheating in hybrid inflation. This scenario involves at least two scalar fields, the inflaton field $\phi$, and the symmetry breaking field $\sigma$. We found that the behavior of these fields after inflation, as well ... More

Tilted Hybrid InflationDec 13 1996We propose a new version of the hybrid inflation scenario that produces a significantly tilted n>1 spectrum of curvature perturbations. This may happen in supersymmetric models where the inflaton field acquires a mass proportional to the Hubble constant, ... More

STATIONARY SOLUTIONS IN BRANS-DICKE STOCHASTIC INFLATIONARY COSMOLOGYApr 15 1995In Brans-Dicke theory the Universe becomes divided after inflation into many exponentially large domains with different values of the effective gravitational constant. Such a process can be described by diffusion equations for the probability of finding ... More

Open Hybrid InflationJan 22 1997We propose an open hybrid inflation scenario that produces an open universe with a `tilted' n>1 spectrum of metric perturbations. The model contains a symmetry breaking field that tunnels to its true vacuum, producing a single bubble inside which hybrid ... More

Stationarity of Inflation and Predictions of Quantum CosmologyAug 04 1994We describe several different regimes which are possible in inflationary cosmology. The simplest one is inflation without self-reproduction of the universe. In this scenario the universe is not stationary. The second regime, which exists in a broad class ... More

Is Warm Inflation Possible?Sep 16 1998We show that it is extremely difficult and perhaps even impossible to have inflation supported by thermal effects.

GRAVITY AND GLOBAL SYMMETRIESFeb 12 1995Apr 27 1995There exists a widely spread notion that gravitational effects can strongly violate global symmetries. It may lead to many important consequences. We will argue, in particular, that nonperturbative gravitational effects in the axion theory lead to a strong ... More

Comments on "Analytic and Numerical Study of Preheating Dynamics"Aug 15 1996In a recent paper Boyanovsky et al (hep-ph/9608205) studied preheating for a particular theory of the inflaton field. Although they results essentially confirm those of the original papers on reheating after inflation, they claimed that most of the earlier ... More

Stationary Measure in the MultiverseDec 01 2008We study the recently proposed "stationary measure" in the context of the string landscape scenario. We show that it suffers neither from the "Boltzmann brain" problem nor from the "youngness" paradox that makes some other measures predict a high CMB ... More

Islands in the landscapeJan 10 2007The string theory landscape consists of many metastable de Sitter vacua, populated by eternal inflation. Tunneling between these vacua gives rise to a dynamical system, which asymptotically settles down to an equilibrium state. We investigate the effects ... More

Gauge field production in SUGRA inflation: local non-Gaussianity and primordial black holesDec 07 2012Apr 27 2013When inflation is driven by a pseudo-scalar field \chi coupled to vectors as \alpha/4 \chi F \tilde F, this coupling may lead to a copious production of gauge quanta, which in turns induces non-Gaussian and non-scale invariant corrections to curvature ... More

Gravitational Particle Production and the Moduli ProblemSep 27 1999Mar 13 2000A theory of gravitational production of light scalar particles during and after inflation is investigated. We show that in the most interesting cases where long-wavelength fluctuations of light scalar fields can be generated during inflation, these fluctuations ... More

Inflation and Preheating in NO modelsMar 16 1999Jun 21 1999We study inflationary models in which the effective potential of the inflaton field does not have a minimum, but rather gradually decreases at large $\phi$. In such models the inflaton field does not oscillate after inflation, and its effective mass becomes ... More

The double attractor behavior of induced inflationJul 16 2014Sep 01 2014We describe an induced inflation, which refers to a class of inflationary models with a generalized non-minimal coupling $\xi g(\phi) R$ and a specific scalar potential. The defining property of these models is that the scalar field takes a vev in the ... More

Inflationary Theory and Alternative CosmologyJun 11 2002Sep 02 2002Recently Hollands and Wald argued that inflation does not solve any of the major cosmological problems. We explain why we disagree with their arguments. They also proposed a new speculative mechanism of generation of density perturbations. We show that ... More

Instant PreheatingDec 09 1998Dec 12 1998We describe a new efficient mechanism of reheating. Immediately after rolling down the rapidly moving inflaton field $\phi$ produces particles $\chi$, which may be either bosons or fermions. This is a nonperturbative process which occurs almost instantly; ... More

M/String Theory, S-branes and Accelerating UniverseApr 28 2003May 07 2003Recently it was observed that the hyperbolic compactification of M/string theory related to S-branes may lead to a transient period of acceleration of the universe. We study time evolution of the corresponding effective 4d cosmological model supplemented ... More

Observational consequences of chaotic inflation with nonminimal coupling to gravityJan 13 2011Feb 24 2011Recently there was an extensive discussion of Higgs inflation in the theory with the potential \lambda(\phi^2-v^2)^2 and nonminimal coupling to gravity {\xi\over 2}\phi^2R, for \xi >> 1 and v<< 1. We extend this investigation to the theories m^2\phi^2 ... More

Planck 2018 and Brane Inflation RevisitedNov 02 2018We revisit phenomenological as well as string-theoretical aspects of D-brane inflation cosmological models. Phenomenologically these models stand out on par with $\alpha$-attractors, as models with Planck-compatible values of $n_s$, moving down to the ... More

Supersymmetry Breaking due to Moduli Stabilization in String TheoryNov 07 2011Mar 05 2012We consider the phenomenological consequences of fixing compactification moduli. In the simplest KKLT constructions, stabilization of internal dimensions is rather soft: weak scale masses for moduli are generated, and are of order m_\sigma ~ m_{3/2}. ... More

Coupling the Inflationary Sector to MatterFeb 25 2016Mar 12 2016We describe the coupling of matter fields to an inflationary sector of supergravity, the inflaton $\Phi$ and a stabilizer $S$, in models where the Kahler potential has a flat inflaton direction. Such models include, in particular, advanced versions of ... More