8 research outputs found
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A study of the charmonium spectrum through proton-antiproton annihilation: Results and prospects at Fermilab
No full textI give a summary of the technique and results from Fermilab Experiment E760 which studied the Charmonium spectrum by resonant formation in Proton-Antiproton Annihilation; final results on measurements of the {eta}{sub c}, and the search for the {eta}{prime}{sub c} are given. Prospects for the continued study in a new experiment, E835, are also briefly presented
Measurement of the two photon decay of the (Xc0)(1 P-3(0)) state of charmonium
No full textWe report on the decay to two photons of the chi(c0) (1(3)P(0)) charmonium resonance formed in (p) over barp interactions at Fermilab experiment E835. We have measured the product of branching ratios BR(chi(c0) --> (p) over barp) x BR(chi(c0) --> gammagamma) = (6.52 +/- 1.18(stat)(-0.72)(+0.48)(sys)) x 10(-8). Using values from the 2002 PDG, this measurement leads to the partial width Gamma(chi(c0) --> gammagamma) = 2.9 +/- 0.9 keV
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A Search for the singlet-P state h(c)(1**1 P(1)) of charmonium in proton-antiproton annihilations at Fermilab experiment E835p
No full textThe author presents the results of a search for the spin-singlet P-wave state h{sub c}(1{sup 1}P{sub 1}) of charmonium formed through proton-antiproton annihilation at Fermilab experiment E835. The decay channels which were studied were p{bar p} {yields} J/{psi} + X {yields} e{sup +}e{sup -} + X, p{bar p} {yields} J/{psi} + {pi}{sup 0} {yields} e{sup +}e{sup -} + {gamma}{gamma}, p{bar p} {yields} J/{psi} + {pi}{sup 0}{pi}{sup 0} {yields} e{sup +}e{sup -} + 4{gamma}, and the neutral channel p{bar p} {yields} {eta}{sub c}{gamma} {yields} ({gamma}{gamma}){gamma}. The decay p{bar p} {yields} J/{psi}{gamma} {yields} e{sup +}e{sup -}{gamma}, into which {sup 1}P{sub 1} decay is forbidden by C-parity conservation, was also examined for comparison. The 90% confidence upper limits for the decay channels studied in the mass range 3525.1-3527.3 MeV for a {sup 1}P{sub 1} resonance with a presumed width of 1.0 MeV were determined to be B(p{bar p} {yields} {sup 1}P{sub 1}) x B({sup 1}P{sub 1} {yields} J/{psi} + X) {le} 1.8 x 10{sup -7}, B(p{bar p} {yields} {sup 1}P{sub 1}) x B({sup 1}P{sub 1} {yields} J/{psi} + {pi}{sup 0}) {le} 1.2 x 10{sup -7}, and B(p{bar p} {yields} {sup 1}P{sub 1}) x B({sup 1}P{sub 1} {yields} J/{psi}{gamma}) {le} 1.0 x 10{sup -7}. No evidence for a {sup 1}P{sub 1} enhancement was observed in either of the two additional reactions studied; p{bar p} {yields} J/{psi} + {pi}{sup 0}{pi}{sup 0} {yields} e{sup +}e{sup -} + 4{gamma} and p{bar p} {yields} {eta}{sub c}{gamma} {yields} ({gamma}{gamma}){gamma}
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Strong interactions studies with medium energy probes. Progress report, 1993--1994
No full textThis progress report refers to the period August 1993 to September 1994, which includes the second year of the three year period December 1, 1992--November 30, 1995 of our existing research contract. The budget proposal for the third year, December 1, 1994 to November 30, 1995 as originally approved, is also presented. As anticipated in our 1992--1995 proposal, Fermilab E760/E835 on high precision charmonium spectroscopy has remained a major part of our preoccupation and commitment during the last year, and it will remain so in the forthcoming year. In early 1994 we joined the collaboration of the Brookhaven experiment E852 on the spectroscopy of states with exotic quantum numbers. The first successful three month run of E852 was completed on July 31 and preliminary data analysis has been started. Some new commitments have resulted from this collaboration and a separate proposal for supplemental financial support is being prepared for them. At Los Alamos our experiment {number_sign}1274 on search of extremely neutron rich exotic nuclei by pion absorption began making initial measurements a month ago and is expected to take data during the period October 15--November 30, 1994. In addition to the above on-going programs, our Bates proposal (94-01) for a definitive measurement of the quenching of the longitudinal response in quasi-free scattering of electrons from nuclei has been approved with high priority for 600 hours of beam time, and we expect to start the experiment in late 1995
New measurements of the resonance parameters of the chi(c0)(1(3)P(0)) state of charmonium
No full textThe resonance parameters of the X-c0, the 1(3)P(0) state of charmonium, have been measured at the Fermilab Antiproton Accumulator in the reaction (p) over barp --> chi(c0) --> gammaJ/psi --> gamma(e(+)e(-)). A large data sample collected during the year 2000 run yields the results: M(chi(c0)) = 3415.4 +/- 0.4 +/- 0.2 MeV/c(2), Gamma(chi(c0)) = 9.8 +/- 1.0 +/- 0.1 MeV, B(chi(c0) --> (p) over barp) x B(chi(c0) --> gammaJ/psi) x B(J/psi --> (e(+)e(-))) = (1.61 +/- 0.11 +/- 0.08) x 10(-7). Taking B(chi(c0) --> gammaJ/psi) and B(J/psi --> e(+)e(-)) from the literature, we obtain B(chi(c0) --> (p) over barp) = (4.1 +/- 0.3(-0.9)(+1.6)) x 10(-4) and Gamma(chic) --> (p) over barp) = (4.0 +/- 0.4(-0.9)(+1.6)) keV
Precision measurements of the total and partial widths of the ψ (2 S) charmonium meson with a new complementary-scan technique in over(p, ̄) p annihilations
No full textWe present new precision measurements of the ψ (2 S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the ψ (2 S) meson through the processes over(p, ̄) p → e+ e- and over(p, ̄) p → J / ψ + X → e+ e- + X. We measure the width to be Γ = 290 ± 25 (sta) ± 4 (sys) keV and the combination of partial widths Γe+ e- Γover(p, ̄) p / Γ = 579 ± 38 (sta) ± 36 (sys) meV, which represent the most precise measurements to date. © 2007 Elsevier B.V. All rights reserved
Study of the chi(c0)(1(3)P(0)) state of charmonium formed in (p)over-barp annihilations
No full textThe resonance parameters of χ c0, the 31P0 resonance of charmonium, have been measured at the Fermilab Antiproton Accumulator by means of the reaction pp → χc0 → γ J/ψ → γ (e+, e-. The results are M(ψc0) = 3417.4+1.8-1.9 ± 0.2 Me V/c2, Τ(03C8;c0 → pp) × B(ψc0 → J/Ψ γ) × B(J/ψ → e+e−) = 2.89+ 0.67- 0.53 ± 0.14 eV. Using known branching ratios we also obtain Τ (Χc0 → pp) = 8.0+1.9+3.5-1.5-1.9keV. These results are discussed in relation to the other ΧCJ states and to theoretical predictions. © 1999 The American Physical Society
Measurement of the Bc +meson lifetime using Bc +→J/ψμ+νμX decays
No full textThe lifetime of the B+ c meson is measured using semileptonic decays having a J/ψ meson and a muon in the final state. The data, corresponding to an integrated luminosity of 2 fb-1, are collected by the LHCb detector in pp collisions at a centre-of-mass energy of 8 TeV. The measured lifetime is τ = 509 ± 8 ± 12 fs, where the first uncertainty is statistical and the second is systematic
