Measurement of the gamma gamma ---> pi+ pi- and gamma gamma ---> K+ K- processes at energies of 2.4-Gev to 4.1-GeV
Collaboration
17 pages
Published in:
- Phys.Lett.B 615 (2005) 39-49
e-Print:
- hep-ex/0412058 [hep-ex]
Report number:
- BELLE-PREPRINT-2004-39,
- KEK-PREPRINT-2004-80
Experiments:
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Abstract:
We have measured pi+pi- and K+K- production in two-photon collisions using 87.7 /fb 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 |cos theta^{*}| < 0.6. The cross section ratio sigma(gammagamma->K+K-)/sigma(gammagamma->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 gammagamma -> pi+pi- and gammagamma -> K+K- modes.- 12.38.Qk
- 13.66.Bc
- 13.85.Lg
- 13.25.Gv
- Two-photon collisions
- Mesons
- QCD
- Charmonium
- electron positron: colliding beams
- exchange: two-photon
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