Measurement of the gamma gamma - pi(+)pi(-) and gamma gamma - K+K- processes at energies of 2.4-4.1 GeV

摘要

We have measured pi(+)pi(-) and K+K- production in two-photon collisions using 87.7 fb(-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 2.4 GeV < W < 4.1 GeV and angular region broken vertical bar cos theta*broken vertical bar < 0.6. The cross section ratio sigma(gamma gamma -> K+K-)/sigma(gamma gamma -> pi(+)pi(-)) is measured to be 0.89 +/- 0.04(stat.)+/- 0.15(syst.) in the range of 3.0 GeV < W < 4.1 GeV, where the ratio is energy-independent. We observe a sin(-4)theta* behavior of the cross section in the same W range. Production of chi(c0) and chi(c2) mesons is observed in both gamma gamma -> pi(+)pi(-) and gamma gamma -> K+K- modes. (c) 2005 Elsevier B.V. All rights reserved.