First measurement of coherent double neutral-pion photoproduction on the deuteron at incident energies below 0.9 GeV

TL;DR

This study reports the first measurement of the total cross sections for coherent double neutral-pion photoproduction on the deuteron below 0.9 GeV, finding no evidence of the expected $d^*(2380)$ dibaryon resonance.

Contribution

It provides the first experimental data on this reaction at energies below 0.9 GeV, setting upper limits on the dibaryon resonance production cross section.

Findings

No resonance-like behavior observed in the excitation function.

Measured cross sections are consistent with theoretical calculations.

Upper limit of 0.034 μb set for the dibaryon resonance at 90% confidence level.

Abstract

The total cross sections were measured for coherent double neutral-pion photoproduction on the deuteron at incident energies below 0.9 GeV for the first time. No clear resonance-like behavior is observed in the excitation function for $W_{\gamma d}=2.38$--2.61 GeV, where the $d^*(2380)$ dibaryon resonance observed at COSY is expected to appear. The measured excitation function is consistent with the existing theoretical calculation for this reaction. The upper limit of the total cross section is found to be $0.034$~$\mu$b for the dibaryon resonance at $W_{\gamma d}=2.37$~GeV (90\% confidence level) in the $\gamma d \to \pi^0\pi^0 d$ reaction.