Related papers: Multi-photon production in e+e- collisions at sqrt…
The process $e^+e^- \to \omega\pi^0 \to \pi^+\pi^-\pi^0\pi^0$ is studied in the center-of-mass energy region $1.05-2.00$ GeV using data with an integral luminosity of about 35 pb$^{-1}$ collected with the SND detector at the VEPP-2000…
The Born cross sections of the processes $e^+e^- \rightarrow \omega\pi^{0}$ and $e^+e^- \rightarrow \omega\eta$ are measured at center-of-mass energies between 3.773 and 4.701 GeV using a total integrated luminosity of 22.7 fb$^{-1}$…
The production of single charged and neutral intermediate vector bosons in e+e- collisions has been studied in the data collected by the DELPHI experiment at LEP at centre-of-mass energies between 183 and 209 GeV, corresponding to an…
The cross section of the process $e^+e^- \to 3(\pi^+\pi^-)$ has been measured using 22 pb$^{-1}$ of integrated luminosity collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider in the c.m. energy range 1.5 -- 2.0 GeV. The…
Using data samples with an integrated luminosity of 19 fb$^{-1}$ at twenty-eight center-of-mass energies from 3.872 GeV to 4.700 GeV collected with the BESIII detector at the BEPCII electron--positron collider, the process…
The data collected at centre-of-mass energies of 188.6 GeV by ALEPH at LEP, corresponding to an integrated luminosity of 176.2 pb-1, are analysed in a search for pair-produced charged Higgs bosons H+/-. Three analyses are employed to select…
The e+e- -> pi+pi-pi+pi- cross section has been measured using 5.8/pb of integrated luminosity collected with the CMD-2 detector at the VEPP-2M collider. Analysis of the data with a refined efficiency determination and use of both three-…
The cross section for the process $e^+e^- \to \omega\eta$ is measured in the center-of-mass energy range 1.34--2.00 GeV. The analysis is based on data collected with the SND detector at the VEPP-2000 $e^+e^-$ collider. The measured $e^+e^-…
The inclusive production of D$^{*\pm}$ mesons in two-photon collisions is measured with the ALEPH detector at $\epem$ centre-of-mass energies from 183$\unit{GeV}$ to 209$\unit{GeV}$. A total of $360 \pm 27$ D$^{*\pm}$ meson events were…
We report the first measurement of the differential cross section for the process gamma gamma --> eta eta in the kinematic range above the eta eta threshold, 1.096 GeV < W < 3.8 GeV over nearly the entire solid angle range, |cos theta*| <=…
The Born cross sections and effective form factors of the process $e^+e^-\to\Lambda\bar\Sigma^0 + c.c.$ are measured at 14 center-of-mass energy points from 2.3094 to 3.0800 GeV, based on data corresponding to an integrated luminosity of…
A search for stable and long-lived massive particles of electric charge |Q/e| = 1 or 2/3, pair-produced in e+e- collisions at centre-of-mass energies from 130 to 183 GeV, is reported by the OPAL collaboration at LEP. No evidence for…
The production of photon pairs in $e^+e^-\rightarrow f \bar f \gamma\gamma$ processes is studied using exact helicity amplitudes at tree level. Total cross sections, including initial state radiation effects, are given. They are presented…
Jet and di-jet production are studied in collisions of quasi-real photons collected during the LEP2 program at e+e- center-of-mass energies from 189 to 209 GeV. OPAL reports good agreement of NLO perturbative QCD with the measured…
The measurements of the QED reaction $ \EEGG $ performed with the L3 detector are used to search for new physics phenomena beyond the Standard Model. No evidence for these phenomena is found and new limits on their parameters are set. First…
The $e^+ e^- \to K^0_{S}K^0_{L}$ and $e^+ e^- \to K^{-}K^{+}$ cross sections have been measured in the center-of-mass energy range 1004--1060 MeV for 25 energy points with about 2$\div$3\% systematic uncertainties. The analysis is based on…
Exclusive rho rho production in two-photon collisions between a quasi-real, gamma, and a virtual, gamma*, photons is studied at LEP at centre-of-mass energies 89 GeV < sqrt{s} < 209 GeV with a total integrated luminosity of 854.7 pb-1. The…
The energy spectrum for high energy $\gamma$-rays ($E_\gamma \geq 10$ MeV) from the process $pp \to \gamma \gamma X$ emitted at $90^0$ in the laboratory frame has been measured at 216 MeV. The resulting photon energy spectrum extracted from…
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=…
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$^\pm\pi^\mp$,…