The pd --> ^3He eta pi0 reaction at T_p = 1450 MeV

TL;DR

This study measures the cross section of the pd to 3He eta pi0 reaction at 1450 MeV, revealing the involvement of the Delta(1232) isobar and supporting a phase space model with p-wave contributions.

Contribution

First measurement of the pd to 3He eta pi0 reaction at this energy, demonstrating the role of the Delta(1232) isobar in the production mechanism.

Findings

Data support the involvement of Delta(1232) isobar.

Invariant mass distributions match phase space Monte Carlo with p-wave weighting.

Reaction mechanism consistent with p-wave pi0 emission.

Abstract

The cross section for the pd --> ^3He eta pi0 reaction has been measured at a beam energy of 1450 MeV using the WASA detector at the CELSIUS storage ring and detecting one ^3He and four photons from the decays of the two photons. The data indicate that the production mechanism involves the formation of the Delta(1232) isobar. Although the beam energy does not allow the full peak of this resonance to be seen, the invariant masses of all three pairs of final state particles are well reproduced by a phase space Monte Carlo simulation weighted with the p-wave factor of the square of the pi^0 momentum in the ^3Hepi^0 system.