Measurement of the mass splittings between the bb̅χ_b,J(1P) states

Authors

K. W. Edwards, Carleton University
Kenneth A. Bloom, University of Nebraska-LincolnFollow
CLEO Collaboration

Date of this Version

2-1-1999

Comments

Published by American Physical Society. Phys. Rev. D 59, 032003 (1999). http://prd.aps.org. Copyright © 1999 American Physical Society. Permission to use.

Abstract

We present new measurements of photon energies and branching fractions for the radiative transitions Υ(2S) → γχ_b(J=0,1,2)(1P). The masses of the χ_b states are determined from the measured radiative photon energies. The ratio of mass splittings between the χ_b substates, r ≡ [(M_J=2 -M_J=1)/( M_J=1 - M_J=0), with M the χ_b mass, provides information on the nature of the bb̅ confining potential. We find r(1P)=0.542 ±0.022±0.024. This value is somewhat lower than the previous world average, but more consistent with the theoretical expectation that r(1P) < r(2P); i.e., that this mass splitting ratio is smaller for the χ_b (1P) states than for the χ_b (2P) states.