Observation of chicJ radiative decays to light vector mesons

Area of Science:

• Particle Physics
• Quantum Chromodynamics
• Hadron Spectroscopy

Background:

• The study of charmonium states, particularly chi(cJ) mesons, is crucial for understanding the strong force and quantum chromodynamics.
• Previous studies have explored various decay modes of chi(cJ) mesons, but transitions involving light vector mesons require further investigation.

Purpose of the Study:

• To investigate the radiative transitions of chi(cJ) states to light vector mesons (rho(0), omega, phi).
• To measure the branching fractions for observed chi(c1) decays and determine the polarization of the final state meson.

Main Methods:

• Analysis of 2.74 x 10^7 psi(2S) decays collected by the CLEO-c detector.
• Reconstruction of decay channels involving chi(cJ) --> gammaV, where V = rho(0), omega, phi.
• Statistical analysis to determine branching fractions and polarization parameters.

Main Results:

• Observation of the transitions chi(c1) --> gamma rho(0) and chi(c1) --> gamma omega.
• Measured branching fractions: B(chi(c1) --> gamma rho(0)) = (2.43 +/- 0.19 +/- 0.22) x 10^-4 and B(chi(c1) --> gamma omega) = (8.3 +/- 1.5 +/- 1.2) x 10^-5.
• The final state meson in the chi(c1) --> gamma rho(0) transition is found to be dominantly longitudinally polarized.

Conclusions:

• The study provides new measurements for specific chi(cJ) decay modes involving light vector mesons.
• The observed polarization in the chi(c1) --> gamma rho(0) transition offers insights into the underlying dynamics of these decays.
• Upper limits are set for branching fractions of other chi(cJ) states to light vector mesons, constraining theoretical models.