Neutral pion form factor measurement at NA62

TL;DR

This paper reports a measurement of the neutral pion's electromagnetic transition form factor slope using a large sample of Dalitz decays from the NA62 experiment, providing insights into meson structure and constraints on dark photon production.

Contribution

It presents the first measurement of the neutral pion form factor slope in the time-like region using NA62 data, and sets new limits on dark photon production in pion decays.

Findings

Measured the form factor slope from 1.05 million $c^0$ Dalitz decays.

Provided new constraints on dark photon production in $c^0$ decays.

Demonstrated the effectiveness of NA62 in meson decay studies.

Abstract

The NA62 experiment at CERN collected a large sample of charged kaon decays with a highly efficient trigger for decays into electrons in 2007. The kaon beam represents a source of tagged neutral pion decays in vacuum. A measurement of the electromagnetic transition form factor slope of the neutral pion in the time-like region from $1.05\times10^6$ fully reconstructed $\pi^0$ Dalitz decay is presented. The limits on dark photon production in $\pi^0$ decays from the earlier kaon experiment at CERN, NA48/2, are also reported.