Pseudoscalar mesons with symmetric bound state vertex functions on the light front

TL;DR

This paper investigates the electromagnetic properties of pions and kaons using a symmetric light-front bound-state model, successfully fitting experimental data by tuning a regulator parameter.

Contribution

It introduces a symmetric ansatz for the quark-meson vertex in light-front theory and demonstrates its effectiveness in describing meson electromagnetic observables.

Findings

Model fits experimental data after tuning regulator mass to 0.6 GeV.

Electromagnetic form factors are invariant across different frames.

Charge radii are sensitive to quark masses and model parameters.

Abstract

We study the electromagnetic form factors, decay constants and charge radii of the pion and kaon within the framework of light-front field theory formalism where we use an ansatz for the quark-meson interaction bound-state function which is symmetric under exchange of quark and antiquark momentum. The above mentioned observables are evaluated for the $+$ component of the electromagnetic current, $J^+$, in the Breit frame. We also check the invariance of these observables in other frames, whereby both the valance and the non-valence contributions have to be taken into account, and study the sensitivity of the electromagnetic form factors and charge radius to the model's parameters; namely, the quark masses, $m_u=m_d$, $m_{\bar s}$, and the regulator mass, $m_R$. It is found that after a fine tuning of the regulator mass, i.e. $m_R=0.6$ GeV, the model is suitable to fit the available experimental data within the theoretical uncertainties of both the pion and kaon.