ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2005, vol. 615, p. 39-49
Measurement of the γγ → π+π- and γγ → K+K- processes at energies of 2.4-4.1 GeV
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. © 2005 Elsevier B.V. All rights reserved.