Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $\psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}$, $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $\phi = (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $\phi = (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $\psi(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow \psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb.
Summary of results at center-of-mass energies from 3.65 to 3.90 GeV. N(SIG) is the number of E+ E- --> P P events; EPSILON is the detection efficiency; L is the integrated luminosity; (1 + DELTA)(DRESSED) is the initial state radiation correction factor without the vacuum polarization correction; and SIG(OBS), SIG(DRESSED) and SIG(BORN) are the observed cross section, the dressed cross section and the Born cross section, respectively.
The two solutions of the dressed cross section and the corresponding phase angles, PHI.
The cross sections for inelastic photoproduction of J/psi and psi^prime mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 468 pb-1 collected in the period 1996--2007. The psi^prime to J/psi cross section ratio was measured in the range 0.55 < z < 0.9 and 60 < W < 190 GeV as a function of W, z and p_T. Here W denotes the photon-proton centre-of-mass energy, z is the fraction of the incident photon energy carried by the meson and p_T is the transverse momentum of the meson with respect to the beam axis. The J/psi cross sections were measured for 0.1 < z < 0.9, 60 < W < 240 GeV and p_T > 1 GeV. Theoretical predictions within the non-relativistic QCD framework including NLO colour--singlet and colour--octet contributions were compared to the data, as were predictions based on the k_T--factorisation approach.
Cross section ratio PSIPRIME (PSI(2S)) to J/PSI as a function of PT.
Cross section ratio PSIPRIME (PSI(2S)) to J/PSI as a function of W.
Cross section ratio PSIPRIME (PSI(2S)) to J/PSI as a function of Z.
We report the first observation of the $\psi(4415)$ resonance in the reaction $\e^+e^-\to D^0 D^-\pi^+$ and a measurement of its cross section in the center-of-mass energy range $4.0\mathrm{GeV}$ to $5.0\mathrm{GeV}$ with initial state radiation. From a study of resonant structure in $\psi(4415)$ decay we conclude that the $\psi(4415)\to D^0 D^-\pi^+$ decay is dominated by $\psi(4415)\to D \bar D{}^{*}_2(2460)$. We obtain $\mathcal{B}(\psi(4415)\to D^0 D^-\pi^+_{\mathrm {non-resonant}})/\mathcal{B}(\psi(4415)\to D \bar D{}^{*}_2(2460)\to D^0 D^-\pi^+)<0.22$ at 90% C.L. The analysis is based on a data sample collected with the Belle detector with an integrated luminosity of 673 $\mathrm{fb}^{-1}$.
The measured cross section for E+ E- --> D0 D- PI+.
Using the BES-II detector at the BEPC Collider, we measured the lowest order cross sections and the $R$ values ($R=\sigma^0_{e^+e^- \to {\rm hadrons}}/\sigma^0_{e^+e^- \to \mu^+\mu^-}$) for inclusive hadronic event production at the center-of-mass energies of 3.650 GeV, 3.6648 GeV and 3.773 GeV. The results lead to $\bar R_{uds}=2.224\pm 0.019\pm 0.089$ which is the average of these measured at 3.650 GeV and 3.6648 GeV, and $R=3.793\pm 0.037 \pm 0.190$ at $\sqrt{s}=3.773$ GeV. We determined the lowest order cross section for $\psi(3770)$ production to be $\sigma^{\rm B}_{\psi(3770)} = (9.575\pm 0.256 \pm 0.813)~{\rm nb}$ at 3.773 GeV, the branching fractions for $\psi(3770)$ decays to be $BF(\psi(3770) \to D^0\bar D^0)=(48.9 \pm 1.2 \pm 3.8)%$, $BF(\psi(3770) \to D^+ D^-)=(35.0 \pm 1.1 \pm 3.3)%$ and $BF(\psi(3770) \to D\bar{D})=(83.9 \pm 1.6 \pm 5.7)%$, which result in the total non-$D\bar D$ branching fraction of $\psi(3770)$ decay to be $BF(\psi(3770) \to {\rm non}-D\bar D)=(16.1 \pm 1.6 \pm 5.7)%$.
The measured (uncorrected) cross sections.
Lowest order cross sections (corrected for radiative and vacuum polarization effects).. The first DSYS error is the point-to-point systematic error and the secondis the common systematic error.
The Ruds value obtained by averaging the first two energy points.. The first error is the combined statistical and point-to-point systematic error and the DSYS error is the common systematic error.
The cross sections for inelastic photoproduction of J/psi and psi' mesons have been measured in ep collisions with the ZEUS detector at HERA, using an integrated luminosity of 38.0 pb-1. The events were required to have 0.1 < z < 0.9 and 50 < W < 180 GeV, where z is the fraction of the incident photon energy carried by the J/psi in the proton rest frame and W is the photon-proton centre-of-mass energy. The psi' to J/psi cross-section ratio was measured in the range 0.55 < z < 0.9. The J/psi data, for various ranges of transverse momentum, are compared to theoretical models incorporating colour-singlet and colour-octet matrix elements. Predictions of a next-to-leading-order colour-singlet model give a good description of the data, although there is a large normalisation uncertainty. The J/psi helicity distribution for z > 0.4 is compared to leading-order QCD predictions.
Measurment of the total cross section, with various PT thresholds, in the high Z > 0.9 region.
Ratio of cross section for PSI(2S) to J/PSI production. as a function of PT. Statistical errors only.
Ratio of cross section for PSI(2S) to J/PSI production. as a function of W. Statistical errors only.
The exclusive photoproduction of J/psi mesons, gamma p->J/psi p, has been studied in ep collisions with the ZEUS detector at HERA, in the kinematic range 20
The total exclusive J/PSI photoproduction cross section, the differential cross section extrapolated to t=0 and the slope parameter of the exponential t dependence as afunction of W, the photon-proton c.m. energy, for data from J/PSI muon decay.
The total exclusive J/PSI photoproduction cross section as a function of W,the photon-proton c.m. energy, for data from J/PSI electron decays.
The differential cross section extrapolated to t=0 and the slope parameter of the exponential t dependence for exclusive J/PSI photoproduction as a function of W, the photon-proton c.m. energy for data from J/PSI electron decays.
The production of $J/\psi$ mesons in continuum $e^+e^-$ annihilations has been studied with the BABAR detector at energies near the $\Upsilon(4S)$ resonance, approximately 10.6 GeV. The mesons are distinguished from $J/\psi$ production in B decays through their center-of-mass momentum and energy. We measure the cross section $e^+e^-\to J/\psi X$ to be $2.52\pm 0.21\pm 0.21$ pb: for momentum above 2 GeV/c, it is $1.87\pm 0.10\pm 0.15$ pb. We set a 90% confidence level upper limit on the branching fraction for direct $\Upsilon(4S)$\to J/\psi X$ decays at $4.7\times 10^{-4}$.
Cross section measurement.
Exclusive production of $\rho^0$ and $J/\psi$ mesons in e^+ p collisions has been studied with the ZEUS detector in the kinematic range $0.25 < Q^2 < 50 GeV^2, 20 < W < 167 GeV$ for the $\rho^0$ data and $2 < Q^2 < 40 GeV^2, 50 < W < 150 GeV$ for the $J/\psi$ data. Cross sections for exclusive $\rho^0$ and $J/\psi$ production have been measured as a function of $Q^2, W$ and $t$. The spin-density matrix elements $r^{04}_{00}, r^1_{1-1}$ and $Re r^{5}_{10}$ have been determined for exclusive $\rho^0$ production as well as $r^{04}_{00}$ and $r^{04}_{1-1}$ for exclusive $J/\psi$ production. The results are discussed in the context of theoretical models invoking soft and hard phenomena.
Exclusive RHO0 electro- and photo- production and cross sections as a function of Q**2 from the BPC data set.
Exclusive RHO0 electro- and photo- production cross section as a function of W from the BPC data set.
Exclusive RHO0 electro- and photo- production cross sections as a function of W from the DIS data set.
A search is performed for the production of the ψ(2S) in e+e− annihilation at a center-of-mass energy of 4.03 GeV using the BES detector operated at the Beijing Electron Positron Collider (BEPC). The kinematic features of the reconstructed ψ(2S) signal are consistent with its being produced only in association with an energetic photon resulting from initial state radiation (ISR). Limits are placed on ψ(2S) production from the decay of unknown charmonia or metastable hybrids that might be produced in e+e− annihilations at 4.03 GeV. Under the assumption that the observed cross section for ψ(2S) production is due entirely to ISR, the partial width Γee of the ψ(2S) is measured to be 2.07±0.32keV.
PSI(UNSPEC) is considered as a new 3D2 charmonium state. CHI/C(UNSPEC) is considered as any unknown charmonium state. EXOTIC is considered as a metastable hybrid.
We present a measurement of the inelastic, non diffractive J/$\psi$ photoproduction cross section in the reaction $e^{+} p \to e^{+} {J}/\psi X$ with the ZEUS detector at HERA. The J/$\psi$ was identified using both the $\mu^{+}\mu^{-}$ and $e^{+}e^{-}$ decay channels and events were selected within the range $0.4
Cross section for the MU+ MU- decay channel.
Cross section for the MU+ MU- decay channel.
Cross section for the MU+ MU- decay channel.
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