Consistent threshold pi0 electro-production at Q^2=0.05, 0.10, and 0.15 GeV^2/c^2

TL;DR

This paper presents new precise measurements of near-threshold pi0 electro-production at low Q^2 values, covering the full solid angle, and compares the results with theoretical models to test their accuracy.

Contribution

It provides the first comprehensive dataset for pi0 electro-production near threshold at multiple Q^2 values, improving upon previous experiments and enabling better theoretical validation.

Findings

Data agree with Heavy Baryon Chiral Perturbation Theory predictions.

Results show consistency across different Q^2 values.

New measurements surpass previous experimental precision.

Abstract

New, accurate data are presented on the near threshold p(e,e'p)pi^0 reaction in the range of four-momentum transfers between Q^2=0.05 and 0.15GeV^2/c^2. The data were taken with the spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4MeV above threshold. These results supersede the previous analysis based on three separate experiments, and are compared with calculations in Heavy Baryon Chiral Perturbation Theory and with phenomenological models.