Pion and kaon elastic form factors in a refined light-front model

TL;DR

This paper refines a light-front model to accurately compute pion and kaon electromagnetic form factors across all momentum transfers, improving agreement with experimental data and setting the stage for extensions to other mesons.

Contribution

The study introduces a refined light-front model with an optimized regulator mass, enhancing the agreement with experimental data for meson form factors and decay constants.

Findings

Better match with experimental form factors at small q^2

Improved decay constant and charge radius predictions

Model refinement facilitates extension to other meson types

Abstract

Within the framework of light-front field theory, we reassess the electromagnetic form factors of the pion and kaon. Comparison with experiment is made for the full range of momentum transfer, q^2<0, including recent data. The light-front model's single regulator mass, m_R, of the \bar qq bound-state vertex function is initially adjusted to reproduce the weak decay constants, f_\pi\ and f_K, and both meson's charge radii, r_\pi\ and r_K. We study the behavior of these observables under variation of the quark masses and find an optimized parameter set, m_u=m_d, m_s and m_R, for which they are in sensibly better agreement with experiment than in a previous analysis; a feature also observed for the elastic form factors, in particular at small q^2. This model refinement is important in view of an extension to vector and heavy-light mesons.