2017/03/31 by B. Ananthanarayan, Johan Bijnens, Shayan Ghosh
Physics and Astronomy · #Chiral perturbation theory #Constant (computer programming) #High-Energy Particle Collisions Research #Isospin #Mathematical physics #Particle physics #Particle physics theoretical and experimental studies #Physics #Pion #Pion decay constant #Quantum Chromodynamics and Particle Interactions #Quantum electrodynamics #Quark #hep-lat #hep-ph
paper · pdf · doi:10.1140/epjc/s10052-017-5019-y
34 pages, plain latex, 5 figures; v2 is the version that was published, with further corrections in Eqs. (84) [normalization],(87) and (91) [missing lines inserted] of the published version. Compared to v1, minor changes to the text and typos removed, the notation updated in section 5, new section 7 on lattice fits
openalex publication_date 2017/07/01 · arxiv created 2017/10/05 · arxiv updated 2017/10/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
A representation of the two-loop contribution to the pion decay constant in SU(3) chiral perturbation theory is presented. The result is analytic up to the contribution of the three (different) mass sunset integrals, for which an expansion in their external momentum has been taken. We also give an analytic expression for the two-loop contribution to the pion mass based on a renormalized representation and in terms of the physical eta mass. We find an expansion of Fπ and Mπ 2 in the strange-quark mass in the isospin limit, and we perform the matching of the chiral SU(2) and SU(3) low-energy constants. A numerical analysis demonstrates the high accuracy of our representation, and the strong dependence of the pion decay constant upon the values of the low-energy constants, especially in the chiral limit. Finally, we present a simplified representation that is particularly suitable for fitting with available lattice data.