Inflationary Magnetogenesis without the Strong Coupling Problem II: Constraints from CMB anisotropies and B-modes

Recent observational claims of magnetic fields stronger than $10^{-16}$ G in the extragalactic medium motivate a new look for their origin in the inflationary magnetogenesis models. In this work we shall review the constraints on the simplest gauge invariant model $f^2(\phi)F_{\mu \nu}F^{\mu \nu}$ of inflationary magnetogenesis, and show that in the optimal region of parameter space the anisotropic constraints coming from the induced bispectrum, due to the generated electromagnetic fields, yield the strongest constraints. In this model, only a very fine tuned scenario at an energy scale of inflation as low as $10^{-2}$ GeV can explain the observations of void magnetic fields. These findings are consistent with the recently derived model independent constraints. However, if the detection of primordial tensor modes by BICEP2 is confirmed, the possibility of low scale inflation is excluded. Assuming the validity of the BICEP2 claim of a tensor-to-scalar ratio $r=0.2^{+0.07}_{-0.05}$, we provide the updated constraints on inflationary magnetogenesis. On the Mpc scale, the maximal allowed magnetic field strength from inflation is less than $10^{-30}$ G.Comment: 13 pages, 5 figures, V2: References added and minor typos corrected to match published versio

Asymptotic symmetries in de Sitter and inflationary spacetimes

Soft gravitons produced by the expansion of de Sitter can be viewed as the Nambu-Goldstone bosons of spontaneously broken asymptotic symmetries of the de Sitter spacetime. We explicitly construct the associated charges, and show that acting with the charges on the vacuum creates a new state equivalent to a change in the local coordinates induced by the soft graviton. While the effect remains unobservable within the domain of a single observer where the symmetry is unbroken, this change is physical when comparing different asymptotic observers, or between a transformed and un-transformed initial state, consistent with the scale-dependent statistical anisotropies previously derived using semiclassical relations. We then compute the overlap, $\langle0| 0'\rangle$, between the unperturbed de Sitter vacuum $|0\rangle$, and the state $| 0'\rangle$ obtained by acting $\mathcal{N}$ times with the charge. We show that when $\mathcal{N}\to M_p^2/H^2$ this overlap receives order one corrections and $\langle0| 0'\rangle\to 0$, which corresponds to an infrared perturbative breakdown after a time $t_{dS} \sim M_p^2/H^3$ has elapsed, consistent with earlier arguments in the literature arguing for a perturbative breakdown on this timescale. We also discuss the generalization to inflation, and rederive the 3-point and one-loop consistency relations.Comment: 22 pages + appendices, 3 figures. V2: Typos fixed, references and clarifications adde

de Sitter limit of inflation and nonlinear perturbation theory

We study the fourth order action of the comoving curvature perturbation in an inflationary universe in order to understand more systematically the de Sitter limit in nonlinear cosmological perturbation theory. We derive the action of the curvature perturbation to fourth order in the comoving gauge, and show that it vanishes sufficiently fast in the de Sitter limit. By studying the de Sitter limit, we then extrapolate to the n'th order action of the comoving curvature perturbation and discuss the slow-roll order of the n-point correlation function.Comment: 14 pages, 1 figure; typos corrected and discussion of tensor modes adde

Nonlocality vs. complementarity: a conservative approach to the information problem

A proposal for resolution of the information paradox is that "nice slice" states, which have been viewed as providing a sharp argument for information loss, do not in fact do so as they do not give a fully accurate description of the quantum state of a black hole. This however leaves an information *problem*, which is to provide a consistent description of how information escapes when a black hole evaporates. While a rather extreme form of nonlocality has been advocated in the form of complementarity, this paper argues that is not necessary, and more modest nonlocality could solve the information problem. One possible distinguishing characteristic of scenarios is the information retention time. The question of whether such nonlocality implies acausality, and particularly inconsistency, is briefly addressed. The need for such nonlocality, and its apparent tension with our empirical observations of local quantum field theory, may be a critical missing piece in understanding the principles of quantum gravity.Comment: 11 pages of text and figures, + references. v2 minor text. v3 small revisions to match final journal versio

South Africa, the arts and youth in conflict with the law

This paper describes the DIME (Diversion into Music Education) youth intervention program that originated in South Africa in 2001. DIME offers instruction in African marimba and djembe bands to juvenile offenders. Conceived as a community collaboration among organizations in the cities of Cape Town, SA and Tampa, USA (including the University of the Western Cape and the University of South Florida), DIME offers a unique example of community music and multicultural music education.Web of Scienc

Low-scale Quintessential Inflation

In quintessential inflationary model, the same master field that drives inflation becomes, later on, the dynamical source of the (present) accelerated expansion. Quintessential inflationary models require a curvature scale at the end of inflation around $10^{-6}M_{\rm P}$ in order to explain the large scale fluctuations observed in the microwave sky. If the curvature scale at the end of inflation is much smaller than $10^{-6}M_{\rm P}$, the large scale adiabatic mode may be produced thanks to the relaxation of a scalar degree of freedom, which will be generically denoted, according to the recent terminology, as the curvaton field. The production of the adiabatic mode is analysed in detail in the case of the minimal quintessential inflationary model originally proposed by Peebles and Vilenkin.Comment: 25 pages; 5 figure

Enhancing the tensor-to-scalar ratio in simple inflation

We show that in theories with a nontrivial kinetic term the contribution of the gravitational waves to the CMB fluctuations can be substantially larger than that is naively expected in simple inflationary models. This increase of the tensor-to-scalar perturbation ratio leads to a larger B-component of the CMB polarization, thus making the prospects for future detection much more promising. The other important consequence of the considered model is a higher energy scale of inflation and hence higher reheating temperature compared to a simple inflation.Comment: 9 pages, 1 figure and references are added, discussion is slightly extended, published versio