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Sign of the color-hyperfine splitting in charmonium P states as a test of perturbative QCD

Journal Article · · Physical Review, D (Particles Fields); (United States)
 [1]; ;  [2]
  1. Physics Department, Indiana University, Bloomington, Indiana 47405 (United States)
  2. Dipartimento di Fisica Teorica, Universita di Torino, Torino (Italy) Istituto Nazionale di Fisica Nucleare Sezione di Torino, I-10125 Torino (Italy)
The sign of the difference in energy between the center of gravity of the {sup 3}{ital P} levels and the {sup 1}{ital P} level in heavy quarkonium is a test of the {alpha}{sub {ital s}}{sup 2} terms in perturbative QCD with a fixed coupling constant. Whereas this energy difference is zero in the Fermi-Breit approximation and greater than zero in a generalized Fermi-Breit approximation with asymptotically free potentials, the energy difference is negative in perturbative QCD calculations to one-loop order with a fixed {alpha}{sub {ital s}}. For potentials which reasonably agree with the spin-averaged data, the absolute magnitude of the splitting is calculated to be about 4 MeV or less in charmonium and 2 MeV or less in bottomonium. Since the energy of the {sup 3}{ital P} center of gravity in charmonium is known, a measurement of the energy of the {sup 1}{ital P} level is needed to discriminate between these different schemes. Although the {sup 1}{ital P} levels in bottomonium will probably be harder to measure, we also present results for bottomonium.
OSTI ID:
7035590
Journal Information:
Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 45:9; ISSN PRVDA; ISSN 0556-2821
Country of Publication:
United States
Language:
English