Since 2002 Perimeter Institute has been recording seminars, conference talks, public outreach events such as talks from top scientists using video cameras installed in our lecture theatres. Perimeter now has 7 formal presentation spaces for its many scientific conferences, seminars, workshops and educational outreach activities, all with advanced audio-visual technical capabilities.
Recordings of events in these areas are all available and On-Demand from this Video Library and on Perimeter Institute Recorded Seminar Archive (PIRSA). PIRSA is a permanent, free, searchable, and citable archive of recorded seminars from relevant bodies in physics. This resource has been partially modelled after Cornell University's arXiv.org.
Accessibly by anyone with internet, Perimeter aims to share the power and wonder of science with this free library.
In this talk I will discuss several recent advances in loop quantum cosmology and its extension to inhomogeneous models. I will focus on spherically symmetric spacetimes and Gowdy cosmologies with local rotational symmetry in vacuum. I will discuss how to implement a quantum Hamiltonian evolution on these quantizations. Then, I will focus on how we can extract predictions from those quantum geometries, and finally analyze a concrete example: cosmological perturbations on Bianchi I spacetimes in LQC.
The power spectrum for fluctuations in the number density of galaxies can be very different in shape from the power spectrum for fluctuations in the mass density at very small wave vectors (i.e., large length scales) if the primordial density fluctuations are non-Gaussian. I review this phenomena. (It is fairly well known in the more astrophysical part of the cosmology community but less so in the particle physics part of the field.) Then I show that primordial non-Gaussianities that arise from quantum loop diagrams in de-Sitter space can give rise to this phenomena.
An increasing number of researchers are considering the possibility that the Standard Model, appropriately extended, can attain an interacting ultraviolet fixed point. Such a theory could, in the Wilsonian sense, be regarded as a fundamental theory. I will describe recent work that shows this goal is attainable in principle by adding gauged vector-like fermions to the Standard Model, in the limit of a large number of fermion fields.
When a particle is accelerated, as in a scattering event, it will radiate gravitons and, if electrically charged, photons. The infrared tail of the spectrum of this radiation has a divergence: an arbitrarily small amount of total energy is divided into an arbitrarily large number of radiated bosons.
I will present constraints from central charges and gradient flow relations on UV and IR interacting fixed points under perturbative control. It is possible to extend this methodology beyond perturbation theory for supersymmetric theories where the central charges are calculated to all orders. In this case, these constraints draw a complex map of possible RG flows, some of them compatible with Asymptotic Safety. Examples of such SUSY theories are discussed
Including a large number of vector-like fermions can be used to generate fixed points for the RG flows of gauge theories. Recently this has been used as a foundation for constructing UV safe models. The talk will focus on the machinery behind the large N_f computations extended to generic gauge-Yukawa theories. For semi-simple gauge theories the phase diagram shows the persistence that the UV fixed point of simple gauge theories.
The nature of dark matter is one of the outstanding riddles of fundamental physics. Here, I will discuss first steps to explore dark matter in the asymptotic safety paradigm. As a first example, I will show indications for an asymptotically safe fixed point in the Higgs portal to fermionic dark matter, leading to a relation between the Higgs portal coupling and the dark matter mass. This model also serves as an example for different mechanisms that generate asymptotic safety.
Check back for details on the next lecture in Perimeter's Public Lectures Series