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Register a new userPrecision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations
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We present new precision measurements of the psi(2S) 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 psi(2S) meson through the processes pbar p -> e+ e- and pbar p -> J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +- 4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp / Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise measurements to date.
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The resonance parameters of the excited psi-family resonances, namely the psi(4040), psi(4160), and psi(4415), were determined by fitting the R-values measured by experiments. It is found that the previously reported leptonic partial widths of these states were merely one possible solutions among a four-fold ambiguity. By fitting the most precise experimental data on the R-values measured by the BES collaboration, this work presents all four sets of solutions. These results may affect the interpretation of the charmonium and charmonium-like states above 4GeV/c^2.
This report reviews the achievements of the Crystal Barrel experiment at the Low Energy Antiproton Ring (LEAR) at CERN. During seven years of operation Crystal Barrel has collected very large statistical samples in pbarp annihilation, especially at rest and with emphasis on final states with high neutral multiplicity. The measured rates for annihilation into various two-body channels and for electromagnetic processes have been used to test simple models for the annihilation mechanism based on the quark internal structure of hadrons. From three-body annihilations three scalar mesons, a0(1450), f0(1370) and f0(1500) have been established in various decay modes. One of them, f0(1500), may be identified with the expected ground state scalar glueball.
We measure the mass of the eta meson using psi(2S) --> eta J/psi events acquired with the CLEO-c detector operating at the CESR e+e- collider. Using the four decay modes eta --> gamma gamma, 3pi0, pi+pi-pi0, and pi+pi-gamma, we find M(eta)=547.785 +- 0.017 +- 0.057 MeV, in which the first uncertainty is statistical and the second systematic. This result has an uncertainty comparable to the two most precise previous measurements and is consistent with that of NA48, but is inconsistent at the level of 6.5sigma with the much smaller mass obtained by GEM.
Using 53 pb$^{-1}$ of $e^+e^-$ annihilation data taken at $sqrt{s}=3.686$ GeV, a comprehensive study has been made of the radiative decays of samples of 5.1 million $J/psi$ and 24.5 million $psi(2S)$ into pairs of pseudoscalar mesons, $pi^+pi^-$, $pi^0pi^0$, $K^+K^-$, $K_S^0K_S^0$, and $etaeta$. Product branching fractions for the radiative decays of $J/psi$ and $psi(2S)$ to scalar resonances $f_0(1370,1500,1710,2100, text{and} 2200)$, and tensor resonances $f_2(1270,1525, text{and} 2230)$ have been determined, and are discussed in relation to predicted glueballs. For $psi(2S)$ radiative decays the search for glueballs has been extended to masses between 2.5 GeV and 3.3 GeV.
The cross-sections of $psi(2S)$ meson production in proton-proton collisions at $sqrt{s}=13~mathrm{TeV}$ are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of $275~pmathrm{b}^{-1}$. The production cross-sections for prompt $psi(2S)$ mesons and those for $psi(2S)$ mesons from $b$-hadron decays ($psi{(2S)}mathrm{-from-}b$) are determined as functions of the transverse momentum, $p_{mathrm{T}}$, and the rapidity, $y$, of the $psi(2S)$ meson in the kinematic range $2<p_{mathrm{T}}<20~mathrm{GeV}/c$ and $2.0<y<4.5$. The production cross-sections integrated over this kinematic region are begin{equation*} begin{split} sigma(mbox{prompt }psi(2S),13~mathrm{TeV}) &= {1.430 pm 0.005(mathrm{stat}) pm 0.099 (mathrm{syst})mumathrm{b}}, sigma(psi(2S)mathrm{-from-}b,13~mathrm{TeV})&={0.426 pm 0.002(mathrm{stat}) pm0.030 (mathrm{syst})mumathrm{b}}. end{split} end{equation*} A new measurement of $psi(2S)$ production cross-sections in $pp$ collisions at $sqrt{s}=7~mathrm{TeV}$ is also performed using data collected in 2011, corresponding to an integrated luminosity of $614~{pmathrm{b}^{-1}}$.The integrated production cross-sections in the kinematic range $3.5<p_{mathrm{T}}<14~mathrm{GeV}/c$ and $2.0<y<4.5$ are begin{equation*} begin{split} sigma(mbox{prompt }psi(2S),7~mathrm{TeV}) &={0.471 pm0.001 (mathrm{stat}) pm 0.025 (mathrm{syst})mumathrm{b}}, sigma(psi(2S)mathrm{-from-}b,7~mathrm{TeV}) &={0.126pm0.001 (mathrm{stat}) pm0.008 (mathrm{syst})mumathrm{b}}. end{split} end{equation*} All results show reasonable agreement with theoretical calculations.
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