Pseudoscalar-Meson Form Factors: A Fresh Look by QCD Sum Rules

TL;DR

This paper reevaluates pseudoscalar meson form factors using QCD sum rules, challenging some recent experimental and theoretical claims about their momentum transfer dependencies.

Contribution

It provides a new analysis of meson form factors with QCD sum rules, questioning certain recent findings and emphasizing fundamental considerations.

Findings

Some theoretical results for the pion elastic form factor are inconsistent with fundamental principles.

An experimental result for the pion-to-photon transition form factor conflicts with general theoretical expectations.

The QCD sum rule approach offers a robust framework for analyzing hadron properties.

Abstract

Confronted with some surprising claims about experimentally measured or theoretically expected dependencies on the involved momentum transfer of various form factors of pseudoscalar mesons, we reassess the present status of these quantities by means of QCD sum rules. This approach provides well-developed and very efficient tools to relate in an analytical manner the parameters of QCD to the empirical properties of hadrons. Within this framework, we show that a few theoretical findings for the pion elastic form factor and one experimental result for the pion-to-photon transition form factor are at odds with rather general fundamental considerations.