Light meson electromagnetic form factors from three-flavor lattice QCD with exact chiral symmetry

TL;DR

This study uses three-flavor lattice QCD with exact chiral symmetry to analyze the electromagnetic form factors of pions and kaons, comparing results with chiral perturbation theory and estimating physical constants.

Contribution

It provides a detailed lattice QCD analysis of meson EM form factors with high precision, incorporating next-to-next-to-leading order chiral effects and employing advanced computational techniques.

Findings

Next-to-next-to-leading order terms are crucial for accurate chiral behavior description.

Estimated low-energy constants align well with experimental data.

Charge radii are consistent with phenomenological results.

Abstract

We study the chiral behavior of the electromagnetic (EM) form factors of pion and kaon in three-flavor lattice QCD. In order to make a direct comparison of the lattice data with chiral perturbation theory (ChPT), we employ the overlap quark action that has exact chiral symmetry. Gauge ensembles are generated at a lattice spacing of 0.11 fm with four pion masses ranging between M_pi \simeq 290 MeV and 540 MeV and with a strange quark mass m_s close to its physical value. We utilize the all-to-all quark propagator technique to calculate the EM form factors with high precision. Their dependence on m_s and on the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields, respectively. A detailed comparison with SU(2) and SU(3) ChPT reveals that the next-to-next-to-leading order terms in the chiral expansion are important to describe the chiral behavior of the form factors in the pion mass range studied in this work. We estimate the relevant low-energy constants and the charge radii, and find reasonable agreement with phenomenological and experimental results.