PIRSA:C10023 - IR issues and loops in de Sitter space - 2010PODCAST Subscribe to podcast

IR issues and loops in de Sitter space


Collection URL: http://pirsa.org/C10023

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New Horizons in Cosmology: The Trace Anomaly, Cosmological Horizon Modes and Dynamical Dark Energy
Speaker(s): Emil Mottola
Abstract: General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degrees of freedom in the extended effective field theory of gravity generated by the trace anomaly of massless quantum fields in curved space. Linea... read more
Date: 27/10/2010 - 9:45 am

IR divergence problem in single-field models of inflation
Speaker(s): Yuko Urakawa
Abstract: We clarify the origin of IR divergence in single-field models of inflation and provide the correct way to calculate the observable fluctuations. First, we show the presence of gauge degrees of freedom in the frequently used gauges such as the comoving gauge and the flat gauge. These gauge degrees of... read more
Date: 27/10/2010 - 11:00 am

Resumming late time divergences and comparing thermal vs dS
Speaker(s): Louis Leblond
Abstract: I will argue that the dynamical renormalization group can be used to resum late time divergences appearing in loop computations in de Sitter. In the case of a scalar field with quartic interactions, the resummed propagator is the massive one. Standard mean field theory techniques can then be used to... read more
Date: 27/10/2010 - 11:45 am

PIRSA:10100065  ( MP4 Medium Res , MP3 , PDF ) Which Format?
The problems of quantum gravity: from high-energy scattering to black holes and cosmology
Speaker(s): Steve Giddings
Abstract: Much work on quantum gravity has focussed on short-distance problems such as non-renormalizability and singularities. However, quantization of gravity raises important long-distance issues, which may be more important guides to the conceptual advances required. These include the problems of black ho... read more
Date: 27/10/2010 - 2:00 pm
Series: Colloquium

The Feynman Propagator and Correlation Functions in an Inflating Spacetime
Speaker(s): Jason Kumar
Abstract: We discuss the definition of the Feynman propagator in de Sitter space. We show that the ambiguities in the propagator zero-mode can be used to make sense of the behavior of low-momentum modes in an inflating space-time. We use this tool to calculate loop corrections to non-Gaussian correlation func... read more
Date: 27/10/2010 - 3:45 pm

Inflationary Correlation Functions without Infrared Divergences
Speaker(s): Arthur Hebecker
Abstract: The definition of correlation functions relies on measuring distances on some late surface of equal energy density. If invariant distances are used, the curvature correlation functions of single-field inflation are free of any IR sensitivity. By contrast, conventional correlation functions, defined ... read more
Date: 27/10/2010 - 4:30 pm

Singular gauges and dS invariance of the graviton vacuum
Speaker(s): Donald Marolf
Abstract: There has been a long-running discussion as to whether free gravitons on dS have a dS-invariant state. On the one hand, de Sitter invariant states are clearly singular in gauges favored by cosmologists; e.g. transverse traceless synchronous gauge associated with the k=0 slicing of dS. However, Higuc... read more
Date: 27/10/2010 - 5:15 pm

Infrared sensitivity of unstable vacua
Speaker(s): Alexander Polyakov
Abstract: TBA
Date: 28/10/2010 - 9:30 am

Particle decay in the de Sitter universe
Speaker(s): Ugo Moschella
Abstract: We study particle decay in the de Sitter spacetime as given by first order perturbation theory in an interacting quantum field theory. We discuss first a general construction of bosonic two-point functions, including a recently discovered class of tachyonic theories that do exist in the de S... read more
Date: 28/10/2010 - 10:45 am

On the Equivalence between Euclidean and In-In Formalisms in de Sitter QFT
Speaker(s): Atsushi Higuchi
Abstract: We study the relation between two sets of correlators in interacting quantum field theory on de Sitter space. The first are correlators computed using in-in perturbation theory in the region of de Sitter space to the future of a cosmological horizon (also known as the expanding cosmological patch, t... read more
Date: 28/10/2010 - 11:30 am

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