Interference study of the chi c0(13P0) in the reaction -pp-->pi0pi0

Area of Science:

• Particle Physics
• High Energy Physics
• Quantum Chromodynamics

Background:

• Charmonium states are crucial for understanding quark-gluon interactions.
• Antiproton-proton annihilation provides a unique channel to study these states.
• Previous studies lacked detailed analysis of specific decay modes like chi(c0) to pi(0)pi(0).

Purpose of the Study:

• To observe and analyze the production of the charmonium state chi(c0) from antiproton-proton annihilation.
• To investigate the decay of chi(c0) into two neutral pions (pi(0)pi(0)).
• To extract key physics parameters, including branching fractions, through partial wave analysis.

Main Methods:

• Utilized data from Fermilab experiment E835.
• Employed partial wave expansion to analyze the angular distribution of the decay products.
• Separated resonant and nonresonant contributions to the pi(0)pi(0) final state.

Main Results:

• Observed the charmonium state chi(c0) decaying into pi(0)pi(0).
• Found an enhanced interference signal between resonant and nonresonant amplitudes.
• Determined the product of branching fractions: B(antiproton-proton --> chi(c0)) x B(chi(c0) --> pi(0)pi(0)) = (5.09 ± 0.81 ± 0.25) x 10^-7.
• Identified dominant partial waves J=0 and J=2, both accessed via L=1 in the antiproton-proton channel.

Conclusions:

• The study confirms the production of chi(c0) in antiproton-proton annihilation and its decay to pi(0)pi(0).
• The observed interference highlights the importance of considering both resonant and continuum processes.
• The extracted branching fractions provide valuable data for refining theoretical models of charmonium physics.