New constraints on the Pion EM form factor using Pi'(-Q^2)

TL;DR

This paper refines constraints on the pion electromagnetic form factor's expansion parameters by integrating space-like and time-like data with QCD polarization derivatives, demonstrating the effectiveness of analyticity techniques.

Contribution

It introduces a novel method combining various data sources and QCD inputs to constrain pion form factor parameters more precisely.

Findings

Stricter bounds on the expansion parameters c and d.

Validation of previous estimates of c using different data.

Enhanced understanding of the pion form factor's behavior.

Abstract

We study the constraints arising on the expansion parameters c and d of the Pion electromagnetic form factor from the inclusion of pure space-like data and the phase of time-like data along with one space-like datum, using as input the first derivative of the QCD polarization amplitude Pi'(-Q^2). These constraints when combined with other analyses, provide a valuable check on a determination of c due to Guo et al. and on our previous work where pionic contribution to the (g-2) of the muon was used as the input. This work further illustrates the power of analyticity techniques in form factor analysis.