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.
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.
We review the status of asymptotically safe gravity-matter systems. The existence of a UV fixed point in such systems is guaranteed if the matter-self couplings are weak and if higher-derivative gravity terms are neglected. We show how this can manifest itself in a functional renormalisation group computation. Such gravity-matter systems contain various avatars of the dynamical Newton's coupling, e.g. gravitational self-couplings or matter-graviton couplings.
A field theory is fundamental if it features a UV fixed point (either trivial or interacting). Gravity may not change drastically the UV behavior if the Einstein gravitational interactions are softened above a critical sub-Planckian energy scale. A concrete implementation of this softened gravity can be obtained by adding terms quadratic in the curvature to the Einstein-Hilbert action. One way to implement this scenario consists in requiring that all matter couplings flow to zero at infinite energy (total asymptotic freedom).
I will discuss how studying the gravitational effects of UV physics on large (astrophysical) scales precludes new mass scales in BSM physics beyond 600 GeV.
Check back for details on the next lecture in Perimeter's Public Lectures Series