Near-threshold production of phi mesons in pp collisions

Area of Science:

• Nuclear Physics
• Particle Physics

Background:

• The Okubo-Zweig-Iizuka (OZI) rule is a fundamental principle in particle physics, predicting suppressed production of certain particles.
• Understanding the phi/omega production ratio provides insights into the validity and limitations of the OZI rule in different reaction environments.

Purpose of the Study:

• To investigate the pp-->ppphi reaction dynamics near the production threshold.
• To determine total and differential cross sections for the pp-->ppphi reaction.
• To compare the measured phi/omega production ratio with theoretical predictions based on the OZI rule.

Main Methods:

• Experiments were conducted at the Cooler Synchrotron COSY-Jülich using an internal beam and the ANKE facility.
• Total cross sections were measured at three excess energies near the production threshold.
• Differential cross sections were analyzed to identify dominant reaction mechanisms.

Main Results:

• The differential cross section near threshold (epsilon=18.5 MeV) showed clear S wave dominance.
• A noticeable effect of the proton-proton final-state interaction was observed.
• The measured phi/omega production ratio was found to be enhanced by a factor of 8 compared to OZI rule predictions.

Conclusions:

• The study provides crucial experimental data on the pp-->ppphi reaction dynamics.
• The significant enhancement of the phi/omega ratio suggests limitations of the OZI rule in this energy regime.
• Further theoretical and experimental investigations are warranted to fully understand the observed phenomenon.