Observation of the h(c)(1P) Using e+ e- collisions above the DD threshold

Area of Science:

• High-energy particle physics
• Experimental particle physics
• Quantum chromodynamics

Background:

• The study of charmonium spectroscopy is crucial for understanding the strong force.
• Investigating the production of charmonium states in electron-positron collisions provides insights into fundamental interactions.

Purpose of the Study:

• To observe and measure the cross section of the process e+ e- → π+ π- hc(1P).
• To search for evidence of the process e+ e- → ηhc(1P).
• To investigate the behavior of the e+ e- → π+ π- hc(1P) cross section at different energies.

Main Methods:

• Utilizing 586 pb⁻¹ of e+ e- collision data collected with the CLEO-c detector at the Cornell Electron Storage Ring.
• Analyzing data at a center-of-mass energy of 4170 MeV.
• Employing normalization with the branching fraction of ψ(2S) → π0 hc(1P).

Main Results:

• Observed the process e+ e- → π+ π- hc(1P) with a measured cross section of 15.6±2.3±1.9±3.0 pb.
• Found evidence for e+ e- → ηhc(1P) at 4170 MeV at the 3σ significance level.
• Observed hints of an increasing cross section for e+ e- → π+ π- hc(1P) at 4260 MeV.

Conclusions:

• The study provides precise measurements of charmonium production in e+ e- collisions.
• The findings contribute to the understanding of the excited charmonium spectrum and strong interaction dynamics.
• Further investigation at different energy points may reveal more about the nature of these particle interactions.