One loop predictions for the pion VFF in Resonance Chiral Theory

TL;DR

This paper presents a one-loop calculation of the pion vector form-factor within Resonance Chiral Theory, providing a prediction for a key low energy constant in Chiral Perturbation Theory at next-to-leading order.

Contribution

It offers the first one-loop computation of the pion VFF in Resonance Chiral Theory with high-energy constraints to predict L9(mu).

Findings

Predicted L9(mu) = (7.6 ± 0.6) x 10^{-3} at 770 MeV.

Next-to-leading order amplitude computed in 1/Nc expansion.

High-energy constraints used to connect resonance theory with Chiral Perturbation Theory.

Abstract

A calculation for the one-loop pion vector form-factor in Resonance Chiral Theory is provided in this talk. The amplitude is computed up to next-to-leading order in 1/Nc and, by means of high-energy constraints, we are able to produce a prediction for the corresponding O(p4) Chiral Perturbation Theory low energy constant L9(mu)=(7.6+- 0.6) 10^{-3} at the scale mu=770 MeV.