#### **AT 1PM** The Pion Mass and Decay Constant at NNNLO in Two-Flavour Chiral Perturbation Theory

- Event time: 1:00pm
- Event date: 1st November 2017
- Speaker: Nils Hermansson Truedsson (Lund University)
- Location: Higgs Centre Seminar Room, 4305 James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB

### Event details

Chiral perturbation theory is a low energy effective field theory built from the approximate chiral symmetry of QCD. The degrees of freedom in this effective theory are the lightest pseudoscalar mesons, and for two quark flavours these are the pions. We have analytically calculated the pion mass and decay constant at NNNLO in the chiral expansion, i.e., to order $p^{8}$, in two-flavour chiral perturbation theory. In this talk, based on hep-ph/1710.01901, I will present the calculation as well as show and discuss the numerical values of the coefficients in the leading-log expansions of the quantities in question.

#### Event resources

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..