We report on a study of the χ 1( 3P 1) and χ 2( 3P 1) states of charmonium formed in antiproton-proton annihilations. An energy scan through the resonances, performed with a very narrow momentum-band beam of antiprotons intersecting a hydrogen jet target, enables us to perform very precise measurements of the mass and the total width of the two resonances. From a sample of 513 χ 1 and 585 χ 2 events we find M χ1 = (3510.53 ± 0.13) MeV/c 2, M χ2 = (3556.15 ± 0.14) MeV/c 2, Γ χ1 = (0.88 ± 0.14) MeV and Γ χ2 = (1.98 ± 0.18) MeV. From our measurement of the quantity Γ(R → p̄p) × BR(R → J/ψγ) × BR(J/ψ/ → e + e -), using known branching ratios, we obtain Γ(χ 1 → p̄p) = (69 ± 13) eV and Γ(χ 2 → p̄p) = (180 ± 31) eV.
Study of the χ1 and χ2 charmonium states formed in p annihilations
MARINELLI, MAURO;PATRIGNANI, CLAUDIA;SANTRONI, ALBERTO;
1992-01-01
Abstract
We report on a study of the χ 1( 3P 1) and χ 2( 3P 1) states of charmonium formed in antiproton-proton annihilations. An energy scan through the resonances, performed with a very narrow momentum-band beam of antiprotons intersecting a hydrogen jet target, enables us to perform very precise measurements of the mass and the total width of the two resonances. From a sample of 513 χ 1 and 585 χ 2 events we find M χ1 = (3510.53 ± 0.13) MeV/c 2, M χ2 = (3556.15 ± 0.14) MeV/c 2, Γ χ1 = (0.88 ± 0.14) MeV and Γ χ2 = (1.98 ± 0.18) MeV. From our measurement of the quantity Γ(R → p̄p) × BR(R → J/ψγ) × BR(J/ψ/ → e + e -), using known branching ratios, we obtain Γ(χ 1 → p̄p) = (69 ± 13) eV and Γ(χ 2 → p̄p) = (180 ± 31) eV.
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