Partial wave analyses of J/ψ→γπ+π− and γπ0π0

Abstract

Results are presented on J / ψ radiative decays to π + π − and π 0 π 0 based on a sample of 58M J / ψ events taken with the BES II detector. Partial wave analyses are carried out using the relativistic covariant tensor amplitude method in the 1.0 to 2.3 GeV / c 2 π π mass range. There are conspicuous peaks due to the f 2 ( 1270 ) and two 0 + + states in the 1.45 and 1.75 GeV / c 2 mass regions. The first 0 + + state has a mass of 1466 ± 6 ± 20 MeV / c 2 , a width of 108 −11 +14 ± 25 MeV / c 2 , and a branching fraction B ( J / ψ → γ f 0 ( 1500 ) → γ π + π − ) = ( 0.67 ± 0.02 ± 0.30 ) × 10 −4 . Spin 0 is strongly preferred over spin 2. The second 0 + + state peaks at 1765 −3 +4 ± 13 MeV / c 2 with a width of 145 ± 8 ± 69 MeV / c 2 . If this 0 + + is interpreted as coming from f 0 ( 1710 ) , the ratio of its branching fractions to ππ and K K ¯ is 0.41 −0.17 +0.11 .