S-Matrix Marathon - Daily Workshop Schedules
Wednesday, March 13, 2024
Title: Dispersion relations in QCD
Speaker: Emilie Passemar
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 pertubative 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. 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 Omnes problem and build the pion vector and scalar form factors 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.
In the second lecture we will discuss how dispersion relations can be a powerful tool to take into account final state interactions of three-hadron system using the Khuri-Treiman approach. We will illustrate considering the eta --> 3pi decay showing how using dispersion relations allows to extract the light quark mass ratio from this decay with a very good precision.
In the third lecture we will discuss the limitations of a dispersive approach to describe amplitudes of physical processes and the state-of-the-art research in the domain to try to overcome some of them in particular coupled channel analyses will be considered.
Time |
| Location |
8:30am | Morning Coffee | Rubenstein Commons Meeting Room 5 |
9:00am | Lecture 1 | Rubenstein Commons Meeting Room 5 |
10:30am | Coffee Break/Discussion | Rubenstein Commons Meeting Room 5 |
11:30am | Lecture 2 | Rubenstein Commons Meeting Room 5 |
1:00-2:00pm | Lunch | Simons Hall |
2:00pm | Lecture 3 | Rubenstein Commons Meeting Room 5 |
3:30pm | Afternoon Tea | Fuld Hall Common Room |
4:30pm | Guided Discussions | Rubenstein Commons Meeting Room 5 |
6:30pm | Dinner | Simons Hall |
Optional IAS Event: Book Talk with Céline Bessière (5:30pm in Rubenstein Commons Café)
https://www.ias.edu/events/book-talk-celine-bessiere for further information and to register