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

We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime. For the theory with a quartic self-interaction, two-point function is calculated up to two loops. Comparing our results Hartree-Fock approximation and stochastic approach shows that former resums only cactus type diagrams, whereas latter contains sunset diagram as well produces correct result. also demonstrate expectation value commutator equal zero both for spacelike timelike separated points.

The Wightman function and the vacuum expectation values of field squared energy-momentum tensor are obtained, for a massive scalar with an arbitrary curvature coupling parameter, in region between two infinite parallel plates, on background de Sitter spacetime. is prepared Bunch-Davies state constrained to satisfy Robin boundary conditions plates. For calculation, mode-summation method used, supplemented variant generalized Abel-Plana formula. This allows one explicitly extract contributions...

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

We compare two different approaches to the treatment of Wheeler-DeWitt equation and introduction time in quantum cosmology. One approach is based on gauge-fixing procedure theories with first-class constraints, while other uses Born-Oppenheimer method. apply both a very simple cosmological model observe that they give similar predictions. also discuss problem non-relativistic mechanics some questions concerning correspondence between classical theories.

Wightman function, the vacuum expectation values of field squared and energy-momentum tensor are investigated for a scalar with general curvature coupling parameter in geometry plate de Sitter spacetime. Robin boundary condition operator is assumed on plate. The presented as sum two terms. first one corresponds to bulk without boundaries second induced by presence We show that non-conformal fields non-diagonal off-diagonal component corresponding energy flux along direction perpendicular In...

The BICEP2 collaboration has for the first time observed B-mode polarization associated with inflationary gravitational waves. Their result some discomfiting implications validity of an effective theory approach to single-field inflation since it would require inflaton field excursion larger than Planck scale. We argue that if quantum state gravitons is a mixed based on Bunch-Davies vacuum, then tensor scalar ratio r measured by BICEP different quantity enters Lyth bound. When this taken...

A bstract We derive the stochastic description of a massless, interacting scalar field in de Sitter space directly from quantum theory. This is done by showing that density matrix for effective theory long wavelength fluctuations obeys version Fokker-Planck equation. equation has simple connection with standard classical theory, which can be generalised to any order perturbation illustrate this formalism detail massless quartic interaction.

In the context of quantum cosmology and Wheeler-DeWitt equation, we investigate possible effects a non-semiclassical wave function Universe on evolution inflationary perturbations. These are associated with behavior homogenous degrees freedom (in particular radius Universe) in early stages expansion, which turn can affect dynamics trans-Planckian modes fields present. The existence bounce for homogeneous gravitational is studied. This lead to an interference between contracting expanding...

We have considered the Pauli-Zeldovich mechanism for cancellation of ultraviolet divergences in vacuum energy. This arises because bosons and fermions give contributions opposite signs. In contrast with preceding papers devoted to this topic wherein mainly free fields were studied, here we taken their interactions into account lowest order perturbation theory. constructed some simple toy models having particles spin 0 1/2, where masses are equal while can be quite non-trivial.

We develop a method for treating the consistency relations of inflation that includes full time-evolution state. This approach relies only on symmetries inflationary setting, in particular residual conformal symmetry spatial part metric, along with general properties which hold any quantum field theory. As result, emerge, are essentially Slavnov-Taylor identities associated this symmetry, apply very generally: they true Green's functions, largely independently model, and can be used...

We develop a method for treating series of secularly growing terms obtained from quantum perturbative calculations: autonomous first-order differential equations are constructed such that they reproduce this to the given order. The exact solutions these free secular and approach finite limit at late times. This technique is illustrated well-known problem growth correlation functions massless scalar field with quartic self-interaction in de Sitter space. For expectation value product two...

We show how the choice of an inflationary state that entangles scalar and tensor fluctuations affects angular two-point correlation functions T, E, B modes cosmic microwave background. The propagators for a starting with some general quadratic entanglement are solved exactly, leading to predictions primordial scalar-scalar, tensor-tensor, scalar-tensor power spectra. These spectra expressed in terms describe entangling structure initial relative standard Bunch-Davies vacuum. illustrate such...

We find exact static solutions of the Einstein equations in spacetime with plane symmetry, where an infinite slab finite thickness and homogeneous energy (mass) density is present. In first solution pressure isotropic, while second tangential components are equal to zero. both cases vanishes at boundaries slab. Outside these matched Rindler Weyl-Levi-Civita spacetime, which represent special Kasner solution.

We check the cancellation of vacuum energy in Wess–Zumino model at two-loop order component field formalisms with and without auxiliary fields. show that both cases is equal to zero. However, formalism where fields are excluded, vanishing arises due between potential kinetic energies, while fields, terms vanish separately.

We analyze the issue of dynamical evolution and time in quantum cosmology. emphasize problem choice phase space variables that can play role a parameter such way for expectation values operators classical is reproduced. show it neither necessary nor sufficient Poisson bracket between variable super-Hamiltonian to be equal unity all space. also discuss question switching different internal times as well Montevideo interpretation theory.

The intricate machinery of perturbative quantum field theory has largely been devoted to the 'dynamical' side theory: simple states are evolved in complicated ways. This article begins address this lopsided treatment. Although it is rarely possible solve for eigenstates an interacting exactly, a general state and its evolution can nonetheless be constructed perturbatively terms propagators structures defined with respect free theory. detailed form initial picture fixed by imposing suitable...

Abstract We examine long-wavelength correlation functions of massive scalar fields in de Sitter spacetime. For the theory with a quartic self-interaction, two-point function is calculated up to two loops. Comparing our results Hartree-Fock approximation and stochastic approach shows that former resums only cactus type diagrams, whereas latter contains sunset diagram as well produces correct result. compare preceding obtained for massless field.