Article
Astronomy & Astrophysics
Eleni-Alexandra Kontou, Ken D. Olum
Summary: This paper demonstrates that eternal inflation is possible even when energy conditions are obeyed. While energy conditions restrict the evolution of any single quantum state, the process of eternal inflation involves selecting a subsector of the previous state, avoiding violation of the conditions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Harry Goodhew, Sadra Jazayeri, Mang Hei Gordon Lee, Enrico Pajer
Summary: This paper discusses the initial conditions of the universe and the impact of quantum mechanics on late-time observables, deriving a set of single-cut rules, discussing the analytical structure of the wave function, and verifying the applicability of these rules in some specific examples.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Arunoday Sarkar, Chitrak Sarkar, Buddhadeb Ghosh
Summary: By defining the k-modes of quantum fluctuations during inflation through the dynamical horizon crossing condition k = aH, and solving the equations of cosmological first-order perturbations self-consistently with chaotic alpha-attractor type potentials, we were able to study the behavior of various parameters in k-space. Comparison with Planck data in the low-k regime constrained the values of the alpha parameter through microscopic calculations. The calculated results matched the Planck-2018 data with 68% or near 95% CL for various values of alpha.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Review
Physics, Multidisciplinary
Henriette Elvang
Summary: This article introduces two highly active research programs, conformal Bootstrap and scattering amplitudes, focusing on the common ideas and methods shared by these two programs, and exploring the possibility of consistent quantum field theories.
REPORTS ON PROGRESS IN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Georgios K. Karananas, Mikhail Shaposhnikov, Andrey Shkerin, Sebastian Zell
Summary: The article explores how Einstein-Cartan gravity can accommodate both global scale and local scale (Weyl) invariance, constructing a wide class of models with nonpropagating torsion and a nonminimally coupled scalar field. It discusses the need for an additional field-dilaton-for global scale invariance, and how the theory reduces to a subclass of one-field models in the case of the Weyl symmetry. The article also derives an equivalent metric theory in both scenarios of scale invariance and discusses possible implications for phenomenology.
Article
Astronomy & Astrophysics
Fulvio Melia
Summary: The recent analysis of Planck data suggests a cutoff in the primordial power spectrum related to the first quantum fluctuation emerging into the semi-classical universe. This has important implications for the question of classicalization.
Article
Astronomy & Astrophysics
Mehrdad Mirbabayi
Summary: By tracing out the environment systematically, we demonstrated the thermalization of out-of-equilibrium states of a light scalar field in a Markovian fashion as perceived by realistic observers. Using the results of Starobinsky and Yokoyama as a case study, we calculated the O(lambda) correction to the relaxation exponents of the lambda phi(4) theory.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Georgios Fanaras, Alexander Vilenkin
Summary: The study uses a path-integral approach to investigate the tunneling wave function in quantum cosmology with spatial topology S1 x S2 and positive cosmological constant. It is found that in this model, creating a universe from nothing requires setting the initial volume to zero and supplementing this with the condition of smooth closure.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
C. P. Burgess, R. Holman, Greg Kaplanek, Jerome Martin, Vincent Vennin
Summary: This study computes the rate at which super-Hubble cosmological fluctuations decohere during inflation, due to their gravitational interactions with unobserved shorter-wavelength scalar and tensor modes. The study utilizes Open Effective Field Theory methods to obtain a minimal result, considering only the self-interactions predicted by General Relativity in single-clock models. The findings reveal that decoherence is suppressed by the first slow-roll parameter and the energy density during inflation, but enhanced by the volume within the scale of interest.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yusuke Yamada
Summary: The paper discusses the adiabatic basis dependence of particle number in time-dependent backgrounds, focusing on preheating after inflation. It shows that the time dependence of the produced particle number can be approximated by a simple connection formula, obtained by analyzing Stokes phenomenon in given backgrounds. The formula can describe various parameter regions such as narrow and broad resonance regime in a unified manner.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Review
Physics, Multidisciplinary
Claudio Coriano, Matteo Maria Maglio
Summary: This article provides an overview of conformal field theories in coordinate space, focusing on the solution of conformal constraints for three- and four-point functions in momentum space. The study discusses the characteristics of correlators containing stress-energy tensors, conserved currents, and scalar operators, along with anomalies and dual conformal solutions identified by CWIs. Perturbative realizations of CFTs at one-loop are also explored, offering insights into the general solutions identified by CWIs for various operators.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2022)
Article
Computer Science, Interdisciplinary Applications
D. X. Horvth, K. Hdsgi, G. Takcs
Summary: The Truncated Conformal Space Approach (TCSA) is an efficient method for computing spectra, operator matrix elements, and time evolution in quantum field theories. The Chirally Factorised TCSA (CFTCSA) algorithm improves the truncation level and allows for more precise calculations and larger Hilbert space dimensions.
COMPUTER PHYSICS COMMUNICATIONS
(2022)
Article
Astronomy & Astrophysics
David Meltzer
Summary: The study focuses on the analytic properties of tree-level wavefunction coefficients in quasi de Sitter space and their application in theories that spontaneously break dS boost symmetries. Cutting rules and dispersion formulas for late-time wavefunction coefficients are derived using factorization and analyticity properties, allowing for the computation of n-point functions by gluing lower-point functions together. It is shown that exchange diagrams constructed from boost-breaking interactions can be expressed as a finite sum over residues.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Damiano Anselmi
Summary: This study investigates primordial cosmology with two scalar fields participating in inflation, revealing the existence of an asymptotically de Sitter cosmic RG flow in two couplings. The importance of quantum gravity theory's predictiveness and the role of RG invariance are highlighted.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Oleg Lebedev
Summary: Stable scalars can be abundantly produced in the Early Universe even without coupling to other fields. The production and mass scale of these scalars during and after (high scale) inflation are studied, leading to strong constraints. Quantum gravity-induced Planck-suppressed operators significantly affect the abundance of dark matter relics, often resulting in overproduction unless the corresponding Wilson coefficients are very small. The uncontrollable nature of these effects without a quantum gravity theory questions the predictability of many non-thermal dark matter models and has potential implications for string theory constructions with abundant scalar fields.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Multidisciplinary
Andrei O. Barvinsky, Diego Blas, Mario Herrero-Valea, Sergey M. Sibiryakov, Christian F. Steinwachs
PHYSICAL REVIEW LETTERS
(2017)
Article
Astronomy & Astrophysics
A. O. Barvinsky, A. Yu. Kamenshchik
Article
Physics, Multidisciplinary
A. O. . Barvinsky
RUSSIAN PHYSICS JOURNAL
(2017)
Article
Physics, Particles & Fields
Andrei O. Barvinsky, Diego Blas, Mario Herrero-Valea, Dmitry V. Nesterov, Guillem Perez-Nadal, Christian F. Steinwachs
JOURNAL OF HIGH ENERGY PHYSICS
(2017)
Article
Astronomy & Astrophysics
Andrei O. Barvinsky, Alexander Yu. Kamenshchik, Tereza Vardanyan
Article
Physics, Particles & Fields
Andrei O. Barvinsky, Diego Blas, Mario Herrero-Valea, Sergey M. Sibiryakov, Christian F. Steinwachs
JOURNAL OF HIGH ENERGY PHYSICS
(2018)
Article
Astronomy & Astrophysics
A. O. Barvinsky, W. Wachowski
Summary: This study presents a systematic method for calculating the covariant expansion of the two-point heat kernel for generic differential operators of any order, which is suitable for renormalization and effective field theory applications. The method generalizes the Schwinger-DeWitt expansion and has been verified to be consistent with known results.
Article
Astronomy & Astrophysics
Andrei O. Barvinsky, Alexander Kurov, Sergey M. Sibiryakov
Summary: By calculating the divergent part of the one-loop effective action in a static background, we derive the full set of beta functions for the marginal essential couplings of projectable Horava gravity in (3 + 1)-dimensional spacetime. The calculation involves reducing the problem to three dimensions, extracting an operator square root, evaluating its trace using universal functional traces, and performing the calculation in four different gauges. We also validate the calculation by evaluating the effective action on a special background using an alternative method.
Article
Astronomy & Astrophysics
A. O. Barvinsky, N. Kolganov, A. Vikman
Summary: This study explores modifications of general relativity by introducing a special noncovariant constraint, resulting in a specific matter stress tensor. By introducing Stueckelberg fields, these gravity models are made covariant, with three of them decoupling dynamically in the case of generalized unimodular gravity. The motivation for GUMG comes from effective field theory.
Article
Astronomy & Astrophysics
A. O. Barvinsky, N. Kolganov
Article
Astronomy & Astrophysics
A. O. Barvinsky, P. Pronin, W. Wachowski
Article
Astronomy & Astrophysics
A. O. Barvinsky, N. Kolganov, A. Kurov, D. Nesterov
Article
Astronomy & Astrophysics
A. O. Barvinsky, D. Carney, P. C. E. Stamp
Article
Astronomy & Astrophysics
Andrey O. Barvinsky, Ariel R. Zhitnitsky