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Photon transitions in Upsilon(2S) and Upsilon(3S) decays.
M Artuso1, C Boulahouache, S Blusk
1Syracuse University, Syracuse, New York 13244, USA.
Physical Review Letters
|February 9, 2005
Summary
This study presents precise measurements of electric dipole photon transitions in Upsilon decays. New data reveals rare E1 transitions and sets limits on M1 transitions, advancing understanding of quarkonium physics.
Area of Science:
- High-energy physics
- Particle physics
- Quantum chromodynamics
Background:
- Quarkonium systems like Upsilon mesons are crucial for testing the Standard Model.
- Understanding transitions between quarkonium states provides insights into fundamental forces.
Purpose of the Study:
- To precisely measure electric dipole (E1) photon transition rates and energies in Upsilon(2S) and Upsilon(3S) decays.
- To measure the rate of a rare E1 transition Upsilon(3S) --> gamma chi(b0)(1P) for the first time.
- To set upper limits on hindered magnetic dipole (M1) transitions to eta(b) states.
Main Methods:
- Analysis of a large statistics data sample collected with the CLEO III detector.
- Study of inclusive photon spectra from Upsilon(2S) and Upsilon(3S) decays.
- Precise measurement of photon energies and transition rates.
Main Results:
- Presented the most precise measurements of E1 photon transition rates and energies for Upsilon(2S) --> gamma chi(bJ)(1P) and Upsilon(3S) --> gamma chi(bJ)(2P) (J = 0, 1, 2).
- Measured the rate for the rare E1 transition Upsilon(3S) --> gamma chi(b0)(1P) for the first time.
- Established upper limits for hindered M1 transitions to eta(b)(1S) and eta(b)(2S) states.
Conclusions:
- The precise measurements contribute significantly to the understanding of quarkonium spectroscopy.
- The observation of new transitions and limits on others refine theoretical models of heavy quark interactions.
- This work enhances the precision of fundamental parameters in particle physics.
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