Study of e+e- --> omega pi0 --> pi0 pi0 gamma in the energy range 1.05--2.00 GeV with SND

TL;DR

This study measures the e+e- --> omega pi0 cross section between 1.05 and 2.00 GeV, providing the most precise data above 1.4 GeV, and tests theoretical models and symmetries with these results.

Contribution

It presents the most accurate measurements of the e+e- --> omega pi0 cross section in the specified energy range and evaluates the VMD model and CVC hypothesis against new data.

Findings

Most accurate cross section data above 1.4 GeV

VMD model describes data below 1.4 GeV

Discrepancy with VMD model in transition form factor

Abstract

The cross section for the process e+e- --> omega pi0 --> pi0 pi0 gamma has been measured in the energy range 1.05--2.00 GeV. The experiment has been performed at the e+e- collider VEPP-2000 with the SND detector. The measured e+e- --> omega pi0 cross section above 1.4 GeV is the most accurate to date. Below 1.4 GeV our data are in good agreement with the previous SND and CMD-2 measurements. Data on the e+e- --> omega pi0 cross section are well described by the VMD model with two excited rho-like states. From the measured cross section we have extracted the gamma^* --> omega pi0 transition form factor. It has been found that the VDM model cannot describe simultaneously our data and data obtained from the omega --> pi0 mu+ mu- decay. We have also tested CVC hypothesis comparing our results on the e+e- --> omega pi0 cross section with data on the tau- --> omega pi- nu_{tau} decay.