期刊
PHYSICAL REVIEW D
卷 79, 期 5, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevD.79.052009
关键词
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资金
- Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan
- Japan Society for the Promotion of Science (JSPS)
- Tau-Lepton Physics Research Center of Nagoya University
- Australian Research Council
- Australian Department of Industry, Innovation, Science and Research
- National Natural Science Foundation of China [10575109, 10775142, 10875115, 10825524]
- Department of Science and Technology of India
- BK21 program of the Ministry of Education of Korea
- CHEP src program and Basic Research program [R01-2008-000-10477-0]
- Korea Science and Engineering Foundation
- Polish Ministry of Science and Higher Education
- Ministry of Education and Science of the Russian Federation
- Russian Federal Agency for Atomic Energy
- Slovenian Research Agency
- Swiss National Science Foundation
- National Science Council
- Ministry of Education of Taiwan
- U.S. Department of Energy
The differential cross sections for the process gamma gamma -> pi(0)pi(0) have been measured in the kinematic range 0.6 GeV < W < 4.1 GeV, vertical bar cos theta* vertical bar < 0.8 in energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. The results are based on a 223 fb(-1) data sample collected with the Belle detector at the KEKB e(+)e(-) collider. The differential cross sections are fitted in the energy region 1.7 GeV < W < 2.5 GeV to confirm the two-photon production of two pions in the G wave. In the higher-energy region, we observe production of the chi(c0) charmonium state and obtain the product of its two-photon decay width and branching fraction to pi(0)pi(0). We also compare the observed angular dependence and ratios of cross sections for neutral-pion and charged-pion pair production to QCD models. The energy and angular dependence above 3.1 GeV are compatible with those measured in the pi(+)pi(-) channel, and in addition we find that the cross section ratio, sigma(pi(0)pi(0))/sigma(pi(+)pi(-)), is 0.32 +/- 0.03 +/- 0.05 on average in the 3.1-4.1 GeV region.
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