Measurement of the γγ → π + π − and γγ → K + K − processes at energies of 2 . 4 – 4 . 1 GeV
نویسندگان
چکیده
We have measured ππ and KK production in two-photon collisions using 87.7 fb of data collected with the Belle detector at the asymmetric energy ee collider KEKB. The cross sections are measured to high precision in the two-photon center-of-mass energy (W ) range between 2.4GeV < W < 4.1GeV and angular region |cos θ∗| < 0.6. The cross section ratio σ(γγ → KK)/σ(γγ → ππ) is measured to be 0.89 ± 0.04(stat.) ± 0.15(syst.) in the range of 3.0GeV < W < 4.1GeV, where the ratio is energy independent. We observe a sin θ∗ behavior of the cross section in the same W range. Production of χc0 and χc2 mesons is observed in both γγ → ππ and γγ → KK modes.
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