283 research outputs found
Measurement of the resonance parameters of the X1(1(3)P(1)) and X2(1(3)P(2)) states of charmonium formed in antiproton-proton annihilations
No full textWe have studied the 3PJ (χcχc) states of charmonium in formation by antiproton–proton annihilations in experiment E835 at the Fermilab Antiproton Source. We report new measurements of the mass, width, and B(χcJ→p ̄p)Γ(χcJ→J/ψ+anything) for the χc1 and χc2 by means of the inclusive reaction p ̄p→χcJ→J/ψ+anything→(e+e−)+anything. Using the subsample of events where χcJ→γ+J/ψ→γ+(e+e−) is fully reconstructed, we derive View the B(χcJ→p ̄p)Γ(χcJ→J/ψ+γ). We summarize the results of the E760 (updated) and E835 measurements of mass, width and B(χcJ→p ̄p)Γ(χcJ→J/ψ+γ) (J=0,1,2) and discuss the significance of these measurements
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
Measurement of the resonance parameters of the X1(1(3)P(1)) and X2(1(3)P(2)) states of charmonium formed in antiproton-proton annihilations
No full textWe have studied the P-3(J) (chi(C)) states of charmonium in formation by antiproton-proton annihilations in experiment E835 at the Fermilab Antiproton Source. We report new measurements of the mass, width, and B(chi(cJ) -> (p) over barp)Gamma(chi(cJ) -> J/psi + anything) for the chi(c1) and chi(c2) by means of the inclusive reaction (p) over barp -> X-cJ -> J/psi + anything -> (e(+)e(-)) + anything. Using the sub-sample of events where chi(cJ) -> gamma + J/psi -> y + (e(+)e(-)) is fully reconstructed, we derive B(chi(cJ) -> (p) over barp)Gamma(chi(cJ) -> J/psi + gamma). We summarize the results of the E760 (updated) and E835 measurements of mass, width and B(chi(cJ) -> (p) over barp)Gamma(chi(cJ) -> J/psi + gamma) (J = 0, 1, 2) and discuss the significance of these measurements
Measurement of the angular distribution in (p)over-barp ->psi(2S)-> e(+)e(-)
No full textWe present the first measurement of the angular distribution for the exclusive process (p) over barp -> psi(2S) -> e(+)e(-) based on a sample of 6844 events collected by the Fermilab E835 experiment. We find that the angular distribution is well described by the expected functional form d N/d cos theta* proportional to 1 + lambda cos(2) theta*, where theta* is the angle between the antiproton and the electron in the center of mass frame, with lambda = 0.67 +/- 0.15(stat) +/- 0.04(sys). The measured value for lambda implies a small but non-zero psi(2S) helicity 0 formation amplitude in (p) over barp, comparable to what is observed in J/psi decays to baryon pairs
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
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
Results of a search for the h(c)(P-1(1)) state of charmonium in the eta(c)gamma and J/psi pi(0) decay modes
No full textWe report evidence for the h(c) state of charmonium in its eta(c)gamma decay mode and lack of evidence in the J/psi pi(0) mode. We studied these channels in (p) over barp annihilations near the center of gravity of the P-3(J) states, where the h(c) was reported in the J/psi pi(0) mode by E760, our previous experiment, at 3526.2 +/- 0.15 +/- 0.2 MeV, with Gamma(R)<= 1 MeV. We observe an event excess in the eta(c)gamma mode near 3526 MeV. Testing the null hypothesis of a linearly varying background cross section against the alternate hypothesis that includes a resonance near 3526 MeV, we reject the null hypothesis with P similar to 0.001. The resonance mass is 3525.8 +/- 0.2 +/- 0.2 MeV and the resonance width <= 1 MeV. We estimate 10.0 +/- 3.5 <Gamma((p) over barp)B(eta c)gamma < 12.0 +/- 4.5 eV, corresponding to fixed values 0.5 <Gamma(R)< 1.0 MeV. We find no event excess within the search region in the J/psi pi(0) mode
Study of psi(2S) decays to gamma p(p)over-bar, pi(0) p(p)over-bar, and eta p(p)over-bar, and search for p(p)over-bar threshold enhancements
No full textThe decays of psi(2S) into gamma p bar{p}, pi^0 p bar{p} and eta p bar{p} have been studied with the CLEO-c detector using a sample of 24.5 million psi(2S) events obtained from e^+e^- annihilations at sqrt{s} = 3686 MeV. The data show evidence for the excitation of several N^* resonances in p pi^0 and p eta channels in pi^0 p bar{p} and eta p bar{p} decays, and f_2 states in gamma p bar{p} decay. Branching fractions for decays of psi(2S) to gamma p bar{p}, pi^0 p bar{p} and eta p bar{p} have been determined. No evidence for p bar{p} threshold enhancements was found in the reactions psi(2S)-> X p bar{p}, where X = gamma, pi^0, eta. We do, however, find confirming evidence for a p bar{p} threshold enhancement in J/psi-> gamma p bar{p} as previously reported by BES
Branching fractions for chi(cJ) -\u3e p(p)over-bar pi(0), p(p)over-bar eta, and p(p)over-bar omega
No full textUsing a sample of 25.9 x 10(6) psi(2S) decays acquired with the CLEO-c detector at the CESR e(+)e(-) collider, we report branching fractions for the decays chi(cJ) -\u3e p (p) over bar pi(0), p (p) over bar eta, and p (p) over bar omega, with J = 0, 1, 2. Our results for B(chi(cJ) -\u3e p (p) over bar pi(0)) and B(chi(cJ) -\u3e p (p) over bar eta) are consistent with, but more precise than, previous measurements. Furthermore, we include the first measurement of B(chi(cJ) -\u3e p (p) over bar omega)
Study of psi(2S) decays to gamma p(p)over-bar, pi(0) p(p)over-bar, and eta p(p)over-bar, and search for p(p)over-bar threshold enhancements
No full textThe decays of psi(2S) into gamma p (p) over bar, pi(0)p (p) over bar, and eta p (p) over bar have been studied with the CLEO-c detector using a sample of 24.5 X 10(6) psi(2S) events obtained from e(+)e(-) annihilations at root s = 3686 MeV. The data show evidence for the excitation of several N* resonances in p pi(0) and p eta channels in pi(0)p (p) over bar and eta p (p) over bar decays, and f(2) states in gamma p (p) over bar decay. Branching fractions for decays of c psi(2S) to gamma p (p) over bar, pi(0)p (p) over bar, and eta p (p) over bar have been determined. No evidence for p (p) over bar threshold enhancements was found in the reactions psi(2S) -\u3e Xp (p) over bar where X = gamma, pi(0), eta. We do, however, find confirming evidence for a p (p) over bar threshold enhancement in J/psi -\u3e gamma p (p) over bar as previously reported by BES
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