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This article is devoted to the study of scalar perturbations in loop quantum cosmology. It aims at clarifying the situation with respect to the way initial conditions are set and to the specific choice of an inflaton potential. Several…

General Relativity and Quantum Cosmology · Physics 2018-10-10 Aurélien Barrau , Pierre Jamet , Killian Martineau , Flora Moulin

The initial value problem for the homogeneous Schr\"odinger equation is investigated for radially symmetric initial data with slow decay rates and not too wild oscillations. Our global wellposedness results apply to initial data for which…

Analysis of PDEs · Mathematics 2020-05-27 Rainer Mandel

We present an explicit formulation of cosmological perturbation theory for three-field models with a flat field space. By performing rotations to align one field with the direction of curvature perturbations and applying the same rotations…

High Energy Physics - Theory · Physics 2026-01-28 Amjad Ashoorioon , Shinji Mukohyama , Kazem Rezazadeh , Navid Talebizadeh

Mainly used to set constraints on cosmological parameters, CMB anisotropies can give information on primordial universe. Unfortunately, initial conditions and late time cosmology are degenerated. I focus on the effect of the shape of the…

Astrophysics · Physics 2007-05-23 Marian Douspis

We consider the fundamental problem of charged particles moving along and around a curved magnetic field line, revising the synchro-curvature radiation formulae introduced by Cheng and Zhang (1996). We provide more compact expressions to…

High Energy Astrophysical Phenomena · Physics 2014-12-10 Daniele Viganò , Diego F. Torres , Kouichi Hirotani , Martín E. Pessah

Many models of the early universe predict that there should be primordial tensor perturbations. These leave an imprint into the temperature and polarisation anisotropies of the cosmic microwave background (CMB). The differential equation…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-04 Darsh Kodwani , P. Daniel Meerburg , Ue-Li Pen , Xin Wang

We compute the spectral distribution of the quantum fluctuations of the vacuum, amplified by inflation, after an arbitrary number of background transitions. Using a graphic representation of the process we find that the final spectrum can…

General Relativity and Quantum Cosmology · Physics 2009-11-07 G. De Risi , M. Gasperini

We investigate the initial conditions problem for multifield inflation. In these scenarios the pre-inflationary dynamics can be chaotic, increasing the sensitivity of the onset of inflation to the initial data even in the homogeneous limit.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Richard Easther , Layne C. Price

In this paper, we develop the radial transfer matrix formalism for unitary one-channel operators. This generalizes previous formalisms for CMV matrices and scattering zippers. We establish an analog of Carmona's formula and deduce criteria…

Mathematical Physics · Physics 2024-10-01 Olivier Bourget , Gregorio Moreno , Christian Sadel , Amal Taarabt

In this paper, we study the interactions of electromagnetic waves with a non-dispersive dynamic medium that is temporally dependent. Electromagnetic fields under material time-modulation conserve their momentum but not their energy. We…

Optics · Physics 2023-07-19 Theodoros T. Koutserimpas , Romain Fleury

In this paper we study the time persistence of superoscillations as the initial data of the time dependent Schr\"odinger equation with $\delta$- and $\delta'$-potentials. It is shown that the sequence of solutions converges uniformly on…

Mathematical Physics · Physics 2019-11-13 Yakir Aharonov , Jussi Behrndt , Fabrizio Colombo , Peter Schlosser

We consider integrable boundary conditions for both discrete and continuum classical integrable models. Local integrals of motion generated by the corresponding transfer matrices give rise to time evolution equations for the initial Lax…

High Energy Physics - Theory · Physics 2009-06-19 Jean Avan , Anastasia Doikou

Near a parity breaking front bifurcation, small perturbations may reverse the propagation direction of fronts. Often this results in nonsteady asymptotic motion such as breathing and domain breakup. Exploiting the time scale differences of…

patt-sol · Physics 2009-10-30 Aric Hagberg , Ehud Meron , I. Rubinstein , B. Zaltzman

We develop new perturbative tools to accurately study radiatively-induced first-order phase transitions. Previous perturbative methods have suffered internal inconsistencies and been unsuccessful in reproducing lattice data, which is often…

High Energy Physics - Phenomenology · Physics 2024-06-12 Andreas Ekstedt , Oliver Gould , Johan Löfgren

We analyse the spectrum of perturbations of the de Sitter space on the one hand, while on the other hand we compute the location of the poles in the Conformal Field Theory (CFT) propagator at the border. The coincidence is striking,…

High Energy Physics - Theory · Physics 2009-11-07 E. Abdalla , K. H. C. Castello-Branco , A. Lima-Santos

In this paper, we provide the first computations for the distortion transfer functions of the cosmic microwave background (CMB) in the perturbed Universe, following up on paper I and II in this series. We illustrate the physical effects…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-07 Thomas Kite , Andrea Ravenni , Jens Chluba

[Abridged] A sharp cut-off in the primordial scalar power spectrum on large scales has been known to improve the fit to the cosmic microwave background (CMB) data when compared to the more standard, nearly scale invariant power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-11 H. V. Ragavendra , Debika Chowdhury , L. Sriramkumar

In this contribution, the transitivity property of commutative first-order linear time-varying systems is investigated with and without initial conditions. It is proven that transitivity property of first-order systems holds with and…

Systems and Control · Computer Science 2021-03-05 Mehmet Emir Koksal

An accelerating electric charge coupled to its own electromagnetic (EM) field both emits radiation and experiences the radiation's reaction as a (self-)force. Considering the system from an Effective Field Theory perspective, and using the…

Classical Physics · Physics 2015-01-22 Ofek Birnholtz

The effect of the initial conditions in inflation on scalar and tensor perturbations is investigated. Formulae for the power spectra of gravitational waves and curvature perturbations for any initial conditions in inflation are derived, and…

High Energy Physics - Theory · Physics 2007-05-23 Shiro Hirai