Related papers: A Search for $\eta'_c$ Production in Photon-Photon…
We report on the observation of the eta_c^' (2 ^1S_0), the radial excitation of eta_c (1 ^1S_0) ground state of charmonium, in the two-photon fusion reaction gamma gamma to eta_c^' to K_S^0 K^{\pm} pi^{\mp} in 13.4 fb^{-1} of CLEO II/II.V…
The two-photon width $\Gamma_{\gamma\gamma}$ of the $\eta_c$ meson has been measured with the L3 detector at LEP. The $\eta_c$ is studied in the decay modes $\pi^+\pi^-\pi^+\pi^-$, $\pi^+\pi^-$K$^+$K$^-$, K$_s^0$K$^\pm\pi^\mp$,…
Using 13.4 $fb^{-1}$ of data collected with the CLEO detector at the Cornell Electron Storage Ring, we have observed 300 events for the two-photon production of ground-state pseudo-scalar charmonium in the decay $\eta_c$ -> $K_S K^{\mp}…
eta_c(2980) production in gamma-gamma interactions has been detected via its decays into K0_s K+/- pi-/+, K+ K- K+ K- and K+ K- pi+ pi- in the data taken with the DELPHI detector at LEP1 and LEP2 energies. The two-photon radiative width…
Using the CLEO-II detector at the CESR $e^+e^-$ storage ring running at the center-of-mass energy around 10.6 GeV, we have studied exclusive production of charmonium states in two-photon collisions. Employing a dataset comprising 3.0 ${\rm…
The DELPHI Collaboration has recently reported the measurement of J/Psi production in photon-photon collisions at LEP II. These newly available data provide an additional proof of the importance of colored c bar{c} pairs for the production…
We argue that an experimental search for an $\eta_c'$, the first radial excitation of the $\eta_c(2980)$, may be carried out using the two photon process $e^+e^- \to e^+e^- \gamma \gamma \ra e^+e^-\eta_c'$. We estimate the partial width…
The pseudoscalar meson eta_b has been searched for in two-photon interactions at LEP II. The data sample corresponds to a total integrated luminosity of 617 pb^{-1} at centre-of-mass energies ranging from 161 to 209 GeV. Upper limits at a…
We present an observation at LEP of the production of chi_c2 mesons in the collisions of two quasi-real photons using the OPAL detector. The chi_c2 mesons are reconstructed in the decay channel Chi_c2 to J/psi gamma to l+l- gamma (with l=…
We report on the observation of the eta_{c}^{prime}(2^{1}S_{0}), the radial excitation of eta_{c}(1^{1}S_{0}) ground state of charmonium, in the two-photon fusion reaction gamma gamma rightarrow eta_{c}^{prime} rightarrow…
Coherent photoproduction of $\pi^0$-mesons from threshold ($E_{th} \approx$ 136 MeV) throughout the $\Delta$-resonance region and of $\eta$-mesons close to the production threshold ($E_{th} \approx$ 570 MeV for $\eta$) has been measured for…
Tau-pair production in the process e+e- -> e+e-tau+tau- was studied using data collected by the DELPHI experiment at LEP2 during the years 1997 - 2000. The corresponding integrated luminosity is 650 pb^{-1}. The values of the cross-section…
Recent BABAR results on two-photon processes are presented. A high statistics study of the two-photon production of the charmonium states eta_c and eta_c(2S) is performed. The mass and width of eta_c and eta_c(2S) are measured; the ratio of…
We analyze 13.8 \rm fb^{-1} of the integrated e^+e^- luminosity collected at 10.6 GeV center-of-mass energy with the CLEO II and CLEO II.V detectors to study exclusive two-photon production of hadrons with masses below 1.7{\rm \ GeV/c^2}…
In this paper we investigate the $\eta_c$ production by photon - photon and photon - hadron interactions in $pp$ and $pA$ collisions at the LHC energies. The inclusive and diffractive contributions for the $\eta_c$ photoproduction are…
Muon pair production in the process e+e- -> e+e-mu+mu- is studied using the data taken at LEP1 (sqrt(s) \simeq m_Z) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb^{-1}. The QED…
The study of electron-positron collisions at center-of-mass energies corresponding to charmonium production has reached new levels of sensitivity thanks to experiments by the BES and CLEO Collaborations. Final states $\gamma P$, where $P$…
First experimental results on photoproduction of eta-mesic nuclei are analyzed. In an experiment performed at the 1 GeV electron synchrotron of the Lebedev Physical Institute, correlated (pi+,n) pairs arising from the reaction \gamma + C12…
First experimental results on photoproduction of eta-mesic nuclei are analyzed. In an experiment performed at the 1 GeV electron synchrotron of the Lebedev Physical Institute, correlated pi+n pairs arising from the reaction gamma + 12C -> N…
Electromagnetic interactions of the ground and first radial excited states of $\eta$ and $\eta'$ mesons in the framework of the extended $U(3)\times U(3)$ NJL model are considered. The radial excitations are described with the help of…