Branching fractions for psi(2S)-to-J/psi transitions

Area of Science:

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

Background:

• The psi(2S) meson is an excited state of the J/psi meson, crucial for understanding quarkonium physics.
• Precise measurements of branching fractions are essential for testing theoretical models of particle decays.
• Previous studies have provided limited or indirect measurements of these specific transitions.

Purpose of the Study:

• To report new, precise measurements of inclusive and exclusive branching fractions for psi(2S) transitions to J/psi.
• To determine branching fractions for chi(cJ) --> gamma(J/psi) and psi(2S) --> light hadrons.
• To enhance the precision of fundamental parameters in particle physics.

Main Methods:

• Analysis of e(+)e(-) collision data collected by the CLEO detector at the CESR collider.
• Measurement of inclusive and exclusive branching fractions for psi(2S) decays.
• Combination of new results with existing CLEO measurements for indirect determinations.

Main Results:

• New, highly precise measurements of branching fractions for psi(2S) to J/psi transitions.
• First direct measurements of certain branching fractions and ratios.
• Determination of B(chi(cJ) --> gamma(J/psi)) and B[psi(2S) --> light hadrons].

Conclusions:

• The study provides the most precise and some of the first direct measurements of key branching fractions.
• These results significantly improve the accuracy of fundamental parameters in particle physics.
• The data will aid in refining theoretical models of quarkonium decays and properties.