Precision measurements of charmonium states formed in pp\uaf annihilation

ermilab experiment E-760 studies the resonant formation of charmonium states in proton-antiproton interactions using a hydrogen gas-jet target in the Antiproton Accumulator ring at Fermilab. Precision measurements of the mass and width of the charmonium states \u3c7c1,\u3c7c2, a direct measurement of the \u3c8\u2019 width, and a new precision measurement of the J/\u3c8 mass are presented

Measurement of the branching ratios psi'->e(+)e(-), psi'->J/psi pi pi, and psi'->J/psi eta RID C-5223-2009

We have observed exclusive decays of the psi' in an experiment where the psi' is formed in antiproton-proton annihilations. We report the branching ratios B(psi' --> e(+)e(-)) = (8.3 +/- 0.5(stat) +/- 0.7(syst)) x 10(-3), B(psi' --> J/psi pi(+)pi(-)) = 0.283 +/- 0.021(stat) +/- 0.020(syst), B(psi' --> J/psi pi(0) pi(0)) = 0.184 +/- 0.019(stat) +/- 0.013(syst), B(pi' --> J/psi eta) = 0.032 +/- 0.010(stat) +/- 0.002(syst)

Measurement of the branching ratios psi'->e(+)e(-), psi'->J/psi pi pi, and psi'->J/psi eta

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Two-body neutral final states produced in antiproton-proton annihilations at 2.911<=root s<=3.686 GeV RID C-5223-2009

We have performed an experiment in the Antiproton Accumulator at Fermilab to study two-body neutral final states formed in annihilations. Differential cross sections are determined in the center-of-mass energy range 2.911< root s<3.686 GeV for the final stares pi(0) pi(0), eta pi(0), eta eta, pi(0) gamma, and gamma gamma. The energy dependence of differential cross sections at 90 degrees in the center of mass is studied to test the predictions of phenomenological QCD scaling hypotheses which predict power-law dependence

STUDY OF THE ETA(C)(1 S-1(O)) STATE OF CHARMONIUM FORMED IN PP ANNIHILATIONS AND A SEARCH FOR THE ETA'(C)(2 S-1(O)) RID C-5223-2009

The E760 Collaboration performed an experiment in the Antiproton Accumulator at Fermilab to study the two photon decay of the eta(c)(1(1)S(0)) charmonium state formed in ($) over bar pp annihilations. This resulted in a new measurement of the mass M(eta c) = 2988.3(-3.1)(+3.3) MeV/c(2) and of the product B(eta(c) --> ($) over bar pp) x Gamma(eta(c) --> gamma gamma) = (8.1(-2.0)(+22.9)) eV. We performed a search for the process ($) over bar pp --> eta(c)'(2(1)S(0)) --> gamma gamma over a limited range of center-of-mass energies. Since no signal was observed, we derived upper limits on the product of branching ratios B(eta(c)' --> ($) over bar pp) x B(eta(c)' --> gamma gamma) in the center-of-mass energy range 3584 less than or equal to root s less than or equal to 3624 MeV. We observed no signal for the nonresonant process ($) over bar p + p --> gamma + gamma and obtain upper limits

Study of the \u3c71 and \u3c72 charmonium states formed in p annihilations

We report on a study of the \u3c7 1( 3P 1) and \u3c7 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 \u3c7 1 and 585 \u3c7 2 events we find M \u3c71 = (3510.53 \ub1 0.13) MeV/c 2, M \u3c72 = (3556.15 \ub1 0.14) MeV/c 2, \u393 \u3c71 = (0.88 \ub1 0.14) MeV and \u393 \u3c72 = (1.98 \ub1 0.18) MeV. From our measurement of the quantity \u393(R \u2192 p\u304p) 7 BR(R \u2192 J/\u3c8\u3b3) 7 BR(J/\u3c8/ \u2192 e + e -), using known branching ratios, we obtain \u393(\u3c7 1 \u2192 p\u304p) = (69 \ub1 13) eV and \u393(\u3c7 2 \u2192 p\u304p) = (180 \ub1 31) eV