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- 19.02., Alessandro Mirizzi (INFN, U Bari): Axions: Bounds and Discovery Opportunities
Abstract: Axions have been introduced in relation to the strong CP problem of the QCD and are predicted in many extensions of the Standard Model of particle physics. Depending on the actual value of their mass, axions can play an important role in cosmology, acting as cold or hot dark matter. The coupling with photons allows for axion-photon mixing in external electromagnetic fields. This effect is exploited for direct searches of axions in laboratory experiments. Axions can be searched also through astrophysical observations. Notably they can be produced in stellar cores leading to an excessive energy loss, that would alter the standard stellar evolution. Furthermore, the two-photon vertex would also induce the mixing with axions for photons emitted by distant astrophysical sources, and propagating in the large-scale cosmic magnetic fields, leading to peculiar observational signature. In this talk I will present an overview of current bounds on axions and discovery opportunities in the planned laboratory and astrophysical experiments.
slides - 19.03., Magdalena Eriksson (NTNU, UiS): Quantum corrections to inflation
Abstract: The theory of cosmic inflation solves the problems of Big Bang cosmology and provides an explanation to the origin of the cosmic microwave background (CMB) radiation. Inflation is often modelled with a scalar field slowly rolling down some potential in FRLW spacetime. In cosmological perturbation theory one perturbs this inflaton field as well as the FRLW metric, and these perturbations can be related to the temperature fluctuations observed in the CMB. In this talk I give an introduction to inflationary cosmology and cosmological correlation functions. I introduce the concept of corrections to these correlation functions and how they can affect the inflationary dynamics. In particular I differentiate between corrections to cosmological observables, i.e. n-point correlation functions, and corrections to the evolving inflaton field and background metric. Corrections to the evolution equations can be viewed as corrections to the slow-rolling parameters, which also enter into observables. - 09.04., Martin Mohajed (NTNU):
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