Special Universe Lecture: Introduction to dispersion relations and application to flavour physics

by Emilie Passemar (Indiana Univ., USA)

Thursday 13 Jul 2017, 15:30 → 17:00 Europe/Berlin

seminar room, basement (Universe Cluster, Boltzmannstr. 2, Garching)

Abstract: For a variety of precision measurements in flavour physics we need to understand strong interactions at an energy scale around 1 GeV. While the description of strong interactions is well understood at high energy where a perturbative expansion applies and at low energy where effective field theories such as Chiral Perturbation Theory for light quarks are very successful, its description in the intermediate energy region is much more problematic. In particular there is no comprehensive theory available to take resonances and their interactions systematically into account. In this lecture we show how this problem can be addressed to some extent using general properties of amplitudes relying on first principles such as unitarity, analyticity and crossing symmetry together with experimental data to successfully extrapolate the chiral perturbation results in a model-independent way in the 1 GeV region. In the first lecture, we will review the so-called Omnès problem and build the pion vector form factor from data. This form factor is very important for many applications in flavour physics. We will discuss one of the most famous ones: the Standard Model prediction of the anomalous magnetic moment of the muon and in particular of the hadronic vacuum polarization.? Emilie will present three lectures on her research. This is part 1. Part 2 on 19th July, 2:15pm and part 3 on 27th July, 11am. Emilie is a Cluster guest. Local host: Martin Jung (Universe Cluster, TUM)