A5060668632- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Particle physics theoretical and experimental studies
- Noncommutative and Quantum Gravity Theories
- Dark Matter and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Galaxies: Formation, Evolution, Phenomena
- Quantum Electrodynamics and Casimir Effect
- Pulsars and Gravitational Waves Research
- High-Energy Particle Collisions Research
- Geophysics and Gravity Measurements
- Physics of Superconductivity and Magnetism
- Solar and Space Plasma Dynamics
- Quantum Mechanics and Applications
- Relativity and Gravitational Theory
- Quantum, superfluid, helium dynamics
- Astronomy and Astrophysical Research
- Computational Physics and Python Applications
- Advanced Chemical Physics Studies
- Advanced Thermodynamics and Statistical Mechanics
- Cold Atom Physics and Bose-Einstein Condensates
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Atomic and Subatomic Physics Research
- Quantum Mechanics and Non-Hermitian Physics
McMaster University
2015-2024
Perimeter Institute
2012-2023
European Organization for Nuclear Research
2008-2023
Dublin Institute For Advanced Studies
2023
Cambridge University Press
2009
McGill University
1989-2004
Institute for Advanced Study
1986-2001
University of New Brunswick
1997
University of Neuchâtel
1994
Université de Montréal
1992
We identify the effective field theory describing physics of super-Hubble scales and show it to be a special case class theories appropriate open systems. Open systems are those that allow information exchanged between degrees freedom interest integrated out, such as would for particles moving through fluid. Strictly speaking they cannot in general described by an lagrangian; rather 'low-energy' limit is instead Lindblad equation time-evolution density matrix slow freedom. derive relevant...
This review summarizes Effective Field Theory techniques, which are the modern theoretical tools for exploiting existence of hierarchies scale in a physical problem. The general framework is described, and explicitly evaluated simple model. Power-counting results illustrated few cases practical interest, several applications to Quantum Electrodynamics described.
We reexamine recent claims that Einstein-frame scattering in the Higgs inflation model is unitary above cut-off energy Λ ≃ M p /ξ. show explicitly how unitarity problems arise both Einstein and Jordan frames of theory. In a covariant gauge they from non-minimal self-couplings, which cannot be removed by field redefinitions because target space not flat. gauge, where there only single scalar can redefined to achieve canonical kinetic terms, through Higgs-gauge couplings.
We introduce a simple string model of inflation, in which the inflaton field can take trans-Planckian values while driving period slow-roll inflation. This leads naturally to realisation large inasmuch as inflationary epoch is well described by single-field scalar potential $V = V_0 (3-4 e^{-\hat\varphi/\sqrt{3}})$. Remarkably, for broad class vacua all adjustable parameters enter only through overall coefficient $V_0$, and particular do not into parameters. Consequently these are determined...
Massless interacting scalar fields in de Sitter space have long been known to experience large fluctuations over length scales larger than Hubble distances. A similar situation arises condensed matter physics the vicinity of a critical point, and this better-understood these indicate failure regime mean-field methods. We argue that for non-Goldstone scalars space, can also be interpreted as signaling complete breakdown semi-classical methods widely used throughout cosmology. By...
We briefly summarize the impact of recent Planck measurements for string inflationary models, and outline what might be expected to learned in near future from improvement sensitivity primordial tensor-to-scalar ratio. comment on whether these models provide sufficient added value compensate their complexity, ask how they fare face new constraints non-gaussianity dark radiation. argue that as a group predictions made before agree well with has been seen, draw conclusions this about is likely...
Though simple inflationary models describe the CMB well, their corrections are often plagued by infrared effects that obstruct a reliable calculation of late-time behaviour. We adapt to cosmology tools designed address similar issues in other physical systems with goal making predictions. The main such tool is Open EFTs which reduce case Stochastic Inflation plus calculable corrections. apply this model complicated enough have dangerous IR behaviour yet allow inference find standard...
These notes present a brief introduction to Hot Big Bang cosmology and Cosmic Inflation, together with selection of some recent attempts embed inflation into string theory. They provide partial description lectures presented in courses at Dubrovnik August 2006, CERN January 2007 Cargese 2007. are aimed graduate students working knowledge quantum field theory, but who unfamiliar the details or
Our current understanding of the Universe is established through pristine measurements structure in cosmic microwave background (CMB) and distribution shapes galaxies tracing large scale (LSS) Universe. One key ingredient that underlies cosmological observables field sources observed assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps most robust theoretical prediction models explain Universe; itis necessarily present even...
Abstract We compute the rate with which unobserved fields decohere other to they couple, both in flat space and de Sitter space, for spectator scalar prepared their standard adiabatic vacuum. The process is very efficient once modes question pass outside Hubble scale, displaying tell-tale phenomenon of secular growth that indicates breakdown perturbative methods on a time scale parameterically long compared time. show how match evolution valid at early times onto late-time Lindblad whose...
We re-examine the predictiveness of single-field inflationary models and discuss how an unknown UV completion can complicate determining model parameters from observations, even precision measurements. Besides usual naturalness issues associated with having a shallow potential, we describe another issue for inflation, namely, physics modifies running Standard Model (SM) thereby introduces uncertainty into potential predictions. illustrate this point using minimal Higgs Inflationary scenario,...
A bstract We examine the motion of light fields near bottom a potential valley in multi-dimensional field space. In case two we identify three general scales, all which must be large order to justify an effective low-energy approximation involving only field, ℓ . (Typically one these — mass heavy transverse trough is used literature when justifying truncation fields.) explicitly compute resulting theory, has form P ( , X ) model, with $ X=-\frac{1}{2}{{\left( {\partial \ell } \right)}^2} as...
The hot dense environment of the early universe is known to have produced large numbers baryons, photons, and neutrinos. These extreme conditions may also other long-lived species, including new light particles (such as axions or sterile neutrinos) gravitational waves. effects any such relics can be observed through their unique imprint in cosmic microwave background (CMB), large-scale structure, primordial element abundances, are important determining initial universe. We argue that future...
Successful inflationary models should (i) describe the data well; (ii) arise generically from sensible UV completions; (iii) be insensitive to detailed fine-tunings of parameters and (iv) make interesting new predictions. We argue that a class with these properties is characterized by relatively simple potentials constant term negative exponentials. here continue earlier work exploring completions for models—including key (though often ignored) issue modulus stabilisation—to assess...