scholarly journals Inflating in a trough: single-field effective theory from multiple-field curved valleys

2013 ◽  
Vol 2013 (1) ◽  
Author(s):  
C. P. Burgess ◽  
M. W. Horbatsch ◽  
Subodh. P. Patil
Keyword(s):  
Effective Theory ◽  
Single Field ◽  
Multiple Field

scholarly journals Large power spectrum and primordial black holes in the effective theory of inflation

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Guillermo Ballesteros ◽  
Sebastián Céspedes ◽  
Luca Santoni
Keyword(s):  
Power Spectrum ◽  
Energy Scale ◽  
Effective Theory ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
De Sitter ◽  
Effective Coupling ◽  
Large Power ◽  
Single Field ◽  
Large Quantum

Abstract We study the generation of a large power spectrum, necessary for primordial black hole formation, within the effective theory of single-field inflation. The mechanisms we consider include a transition into a ghost-inflation-like phase and scenarios where an exponentially growing mode is temporarily turned on. In the cases we discuss, the enhancement in the power spectrum results from either a swift change in some effective coupling or a modification of the dispersion relation for the perturbations, while the background evolution remains unchanged and approximately de Sitter throughout inflation. The robustness of the results is guaranteed thanks to a weakly broken galileon symmetry, which protects the effective couplings against large quantum corrections. We discuss how the enhancement of the power spectrum is related to the energy scale of the operators with weakly broken galileon invariance, and study the limits imposed by strong coupling and the validity of the perturbative expansion.

scholarly journals Cosmological implications of quantum corrections and higher-derivative extension

2015 ◽  
Vol 30 (03n04) ◽  
pp. 1540008 ◽  
Author(s):  
Diego Chialva ◽  
Anupam Mazumdar
Keyword(s):  
Nonlocal Theory ◽  
High Energy ◽  
Effective Theory ◽  
Quantum Corrections ◽  
Derivative Expansion ◽  
Higher Derivative ◽  
Higher Derivatives ◽  
Single Field ◽  
Field Formalism ◽  
Early Universe Cosmology

We discuss the challenges for the early universe cosmology from quantum corrections, and in particular higher-derivative terms, in the gravitational and inflaton sectors of the models. The work is divided in two parts. In the first one we review the already well-known issues due to quantum corrections to the inflaton potential, in particular focusing on chaotic/slow-roll single-field models. We will point out some issues concerning the proposed mechanisms to cope with the corrections, and also argue how the presence of higher-derivative corrections could be problematic for those mechanisms. In the second part we will more directly focus on higher-derivative corrections. We will show how, in order to discuss a number of high-energy phenomena relevant to inflation (such as its actual onset) one has to deal with energy scales where the derivative expansion breaks down, presenting problems such as quantum vacuum instability and ghosts. To discuss such phenomena in the convenient framework of the effective theory, one must then abandon the derivative expansion and resort to the full nonlocal formulation of the theory, which is in fact equivalent to re-integrating back the relevant physics, but with the benefit of using a more compact single-field formalism. Finally, we will briefly discuss possible advantages offered by the presence of higher derivatives and a nonlocal theory to build better controlled UV models of inflation.

scholarly journals NON-GAUSSIANITY FROM THE BISPECTRUM IN GENERAL MULTIPLE FIELD INFLATION

2011 ◽  
Vol 01 ◽  
pp. 203-208
Author(s):  
SHUNTARO MIZUNO ◽  
FREDERICO ARROJA ◽  
KAZUYA KOYAMA
Keyword(s):  
Sound Speed ◽  
Kinetic Term ◽  
Momentum Dependence ◽  
Leading Order ◽  
Point Function ◽  
Curvature Perturbation ◽  
Slow Roll ◽  
Special Cases ◽  
Single Field ◽  
Multiple Field

We study the non-gaussianity from the bispectrum in multi-field inflation models with a general kinetic term. The models include the multi-field K-inflation and the multi-field Dirac-Born-Infeld (DBI) inflation as special cases. We derive the three-point function for the curvature perturbation which depends on both adiabatic and entropy perturbations, in the small sound speed limit and at leading order in the slow-roll expansion. The contribution from the entropy perturbations has a different momentum dependence if the sound speed for the entropy perturbations is different from the adiabatic one, which provides a possibility to distinguish the multi-field models from single field models.

scholarly journals Perturbative unitarity in quasi-single field inflation

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Suro Kim ◽  
Toshifumi Noumi ◽  
Keito Takeuchi ◽  
Siyi Zhou
Keyword(s):  
Quantum Gravity ◽  
Parameter Space ◽  
High Energy ◽  
New Physics ◽  
Energy Scale ◽  
Effective Theory ◽  
Massive Scalar ◽  
High Energy Scale ◽  
Single Field ◽  
High Energy Scattering

Abstract We study implications of perturbative unitarity for quasi-single field inflation with the inflaton and one massive scalar. Analyzing high energy scattering, we show that non-Gaussianities with |fNL| ≳ 1 cannot be realized without turning on interactions which violate unitarity at a high energy scale. Then, we provide a relation between fNL and the scale of new physics that is required for UV completion. In particular we find that for the Hubble scale H ≳ × 109 GeV, Planck suppressed operators can easily generate too large non-Gaussanities and so it is hard to realize successful quasi-single field inflation without introducing a mechanism to suppress quantum gravity corrections. Also we generalize the analysis to the regime where the isocurvature mode is heavy and the inflationary dynamics is captured by the inflaton effective theory. Requiring perturbative unitarity of the two-scalar UV models with the inflaton and one heavy scalar, we clarify the parameter space of the P(X, ϕ) model which is UV completable by a single heavy scalar.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Connecting Gospels

2018 ◽  
Keyword(s):  
Second Century ◽  
Common Belief ◽  
Field Of Study ◽  
Early Christian ◽  
Single Field ◽  
Vantage Points ◽  
Canonical Texts ◽  
Normative Status ◽  
Two Bodies ◽  
Shed Light

By the late second century, early Christian gospels had been divided into two groups by a canonical boundary that assigned normative status to four of them while consigning their competitors to the margins. The project of this volume is to find ways to reconnect these divided texts. The primary aim is not to address the question whether the canonical/non-canonical distinction reflects substantive and objectively verifiable differences between the two bodies of texts—although that issue may arise at various points. Starting from the assumption that, in spite of their differences, all early gospels express a common belief in the absolute significance of Jesus and his earthly career, the intention is to make their interconnectedness fruitful for interpretation. The approach taken is thematic and comparative: a selected theme or topic is traced across two or more gospels on either side of the canonical boundary, and the resulting convergences and divergences shed light not least on the canonical texts themselves as they are read from new and unfamiliar vantage points. The outcome is to demonstrate that early gospel literature can be regarded as a single field of study, in contrast to the overwhelming predominance of the canonical four characteristic of traditional gospels scholarship.

Effective Field Theory in Particle Physics and Cosmology

2020 ◽  
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Particle Physics ◽  
Large Scale ◽  
Effective Field ◽  
Effective Theory ◽  
Soft Collinear Effective Theory ◽  
Multiple Length Scales ◽  
Cosmological Observations ◽  
Standard Models

Effective field theory (EFT) is a general method for describing quantum systems with multiple-length scales in a tractable fashion. It allows us to perform precise calculations in established models (such as the standard models of particle physics and cosmology), as well as to concisely parametrize possible effects from physics beyond the standard models. EFTs have become key tools in the theoretical analysis of particle physics experiments and cosmological observations, despite being absent from many textbooks. This volume aims to provide a comprehensive introduction to many of the EFTs in use today, and covers topics that include large-scale structure, WIMPs, dark matter, heavy quark effective theory, flavour physics, soft-collinear effective theory, and more.

scholarly journals Excited heavy baryons and their symmetries II: Effective theory

2001 ◽  
Vol 692 (3-4) ◽  
pp. 521-545 ◽  
Author(s):  
Chi-Keung Chow ◽  
Thomas D. Cohen ◽  
Boris A. Gelman
Keyword(s):  
Effective Theory ◽  
Heavy Baryons
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