The cross section of the reaction e + e − → K + K − has been measured at the electron-positron storage ring VEPP-2M in the c.m. energy range 1.0–1.4 GeV. At energies above 1.15 GeV the experimental values of the charged kaon form factor considerably exceed the predictions of the simplest vector dominance model with ϱ, ω, ψ mesons.
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The e + e − → K S 0 K L 0 cross section has been measured between 1400 and 2180 MeV. About 58 K S 0 K L 0 events were in the magnetic detector DM1 at the Orsay storage ring DCI. The charged and neutral kaon form factor behaviour suggests the existence of a new isoscalar vector meson at 1.65 GeV.
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Thee+e−→K+K− cross section has been measured from about 750 events in the energy interval\(1350 \leqq \sqrt s\leqq 2400 MeV\) with the DM2 detector at DCI. TheK± form factor |FF±| cannot be explained by the ρ, ω, ϕ and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment.
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RADIATIVE CORRECTIONS APPLIED.
High precision measurements of the form factors of proton, pion, and kaon for timelike momentum transfers of |Q^2|=s=14.2 and 17.4 GeV^2 have been made. Data taken with the CLEO-c detector at sqrt(s)=3.772 GeV and 4.170 GeV, with integrated luminosities of 805 pb^-1 and 586 pb^-1, respectively, have been used to study $e^+e^-$ annihilations into pi+pi-, K+K^-, and ppbar. The perturbative QCD prediction that at large Q^2 the quantity Q^2F(Q^2) for vector mesons is nearly constant, and varies only weakly as the strong coupling constant alpha_S(Q^2) is confirmed for both pions and kaons. In contrast, a significant difference is observed between the values of the corresponding pQCD suggested near-constant quantity, |Q^4|G_M(|Q^2|)/mu_p for protons at |Q^2|=14.2 GeV^2 and 17.4 GeV^2. The results suggest the constancy of |Q^2|G_M(|Q^2|)/mu_p, instead.
Born cross section of $e^+e^-\rightarrow h^+h^-$
Timelike form factor