Measurement of the [formula omitted] and [formula omitted] processes at energies of 2.4–4.1 GeV

Abstract

We have measured π+π− and K+K− production in two-photon collisions using 87.7fb−1 of data collected with the Belle detector at the asymmetric energy e+e− 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 |cosθ∗|<0.6. The cross section ratio σ(γγ→K+K−)/σ(γγ→π+π−) 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−4θ∗ behavior of the cross section in the same W range. Production of χc0 and χc2 mesons is observed in both γγ→π+π− and γγ→K+K− modes.