2.00pm: The 3-loop hadronic vacuum polarization in chiral perturbation theory

Particle Physics Theory seminar

2.00pm: The 3-loop hadronic vacuum polarization in chiral perturbation theory

  • Event time: 1:30pm until 3:30pm
  • Event date: 30th October 2024
  • Speaker: Mattias Sjö (Aix Marseille Université)
  • Location: Room 4325B,

Event details

Title: 

The 3-loop hadronic vacuum polarization in chiral perturbation theory

Abstract: 

Chiral perturbation theory (ChPT) is the effective field theory for low-energy QCD. As such, it describes the same physics as the long-distance modes in lattice QCD simulations. Unlike the lattice, however, ChPT is not confined to a finite Euclidean volume, making it a powerful tool for directly studying the errors introduced by such a finite volume. This is as conceptually straightforward as doing the same equally valid calculation in finite and infinite volume and comparing the difference. In this case, we are looking at the hadronic vacuum polarization (HVP), one of the most intensely studied low-energy QCD quantities due to its relevance to the muon g-2. Since the state of the art for these highly precise calculations now involves 2-loop ChPT finite-volume effects, it is natural to start looking at 3-loop order, both to establish confidence in the convergence of existing calculations, and to prepare for the next level of precision. I describe in detail how we manage this highly complex calculation, which by
necessity has to be as systematic and automatic as possible. In particular, I describe our surprisingly deep and exciting interaction with the frontiers of loop integral technology. Lastly, I also demonstrate how the structure of the conventional infinite-volume calculation can be reused as much as possible in the typically more challenging finite-volume counterpart.

About Particle Physics Theory seminars

The Particle Physics Theory seminar is a weekly series of talks reflecting the diverse interests of the group. Topics include analytic and numerical calculations based on the Standard Model of elementary particle physics, theories exploring new physics, as well as more formal developments in gauge theories and gravity..

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