Litim Abstract

It is commonly believed that a fundamental definition of quantum field theory requires the existence of an UV fixed point. Asymptotic freedom of QCD is the well-known example where the fixed point is non-interacting. In this talk, I provide a proof of existence for novel classes of 4D matter-gauge theories whose high-energy behaviour is governed by an interacting UV fixed point. In the absence of asymptotic freedom, scalars, fermions, and non-Abelian gauge fields cooperate in such a way that an interacting UV fixed point emerges. I discuss the key characteristics of these theories which are all under strict perturbative control. I also discuss recent advances and challenges to find interacting UV fixed points in 4D quantum gravity once couplings become large.  

Anderson Abstract

With the discovery of a Higgs Boson at the LHC, there is the possibility that the Higgs sector is not made up of a single physical boson. At CMS, we have been searching for additional Higgs-like states with masses up to 1 TeV. I will present results from these searches in the semi-leptonic H -> WW -> lvqq final state. This challenging state is able to produce limits from near the WW threshold all the way up to 1 TeV using various techniques including analysis of boosted jet sub-structure. We are able to exclude a large portion of the phase space for an additional electroweak singlet model and interpret our results in terms of a generic search for a scalar particle with a width less than or equal to the Higgs width.  

Neil Abstract

An intriguing theoretical possibility is that dark matter is a neutral composite bound state of electroweak-charged constituents. I will discuss some general features of composite dark matter, and then present a specific model, "stealth dark matter", in which direct detection is mediated by Higgs boson exchange and by the dimension-7 electromagnetic polarizability of the dark matter candidate. Lattice calculations in SU(4) gauge theory, used to determine important matrix elements for this model, will also be presented.

de Alwis Abstract

The theory of cosmological fluctuations assumes that the pre-inflationary state of the universe was the quantum vacuum of a scalar field(s) coupled to gravity. The observed cosmic microwave background fluctuations are then interpreted as quantum fluctuations. Here we consider alternate interpretations of the classic calculations of scalar and tensor power spectra by replacing the quantum vacuum with a classical statistical distribution, and suggest a way of distinguishing the quantum from the classical alternatives. The possibility that the latter is governed by a fundamental length scale as in string theory is also explored.