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.
|Number of pages
|Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
|Published - 2005 May 26
Bibliographical noteFunding Information:
We thank the KEKB group for the excellent operation of the accelerator, the KEK Cryogenics group for the efficient operation of the solenoid, and the KEK computer group and the National Institute of Informatics for valuable computing and Super-SINET network support. We are grateful to V. Chernyak for fruitful discussions. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology of Japan and the Japan Society for the Promotion of Science; the Australian Research Council and the Australian Department of Education, Science and Training; the National Science Foundation of China under contract No. 10175071; the Department of Science and Technology of India; the BK21 program of the Ministry of Education of Korea and the CHEP SRC program of the Korea Science and Engineering Foundation; the Polish State Committee for Scientific Research under contract No. 2P03B 01324; the Ministry of Science and Technology of the Russian Federation; the Ministry of Education, Science and Sport of the Republic of Slovenia; the Swiss National Science Foundation; the National Science Council and the Ministry of Education of Taiwan; and the US Department of Energy.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics