Interference Study of the chi_c0 (1^3P_0) in the Reaction Proton-Antiproton -> pi^0 pi^0

TL;DR

This study investigates the interference effects of the chi_c0 charmonium state in proton-antiproton annihilation producing pi^0 pi^0, revealing detailed amplitude contributions and branching fractions.

Contribution

It provides the first detailed partial wave analysis of chi_c0 interference in proton-antiproton annihilation, extracting key physics parameters and branching ratios.

Findings

Interference signal enhances despite small resonant amplitude.

Amplitudes J=0 and 2 are dominant and of comparable strength.

Measured product of branching fractions: (5.09 ± 0.81 ± 0.25) x 10^-7.

Abstract

Fermilab experiment E835 has observed proton-antiproton annihilation production of the charmonium state chi_c0 and its subsequent decay into pi^0 pi^0. Although the resonant amplitude is an order of magnitude smaller than that of the non-resonant continuum production of pi^0 pi^0, an enhanced interference signal is evident. A partial wave expansion is used to extract physics parameters. The amplitudes J=0 and 2, of comparable strength, dominate the expansion. Both are accessed by L=1 in the entrance proton-antiproton channel. The product of the input and output branching fractions is determined to be B(pbar p -> chi_c0) x B(chi_c0 -> pi^0 pi^0)= (5.09 +- 0.81 +- 0.25) x 10^-7.