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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

Nakazawa H., Uehara S., Abe K., Abe K., Aihara H., Akatsu M., Asano Y., Aulchenko V., Aushev T., Bahinipati S., Bakich A. M., Ban Y., Banerjee S., Bedny I., Bitenc U., Bizjak I., Blyth S., Bondar A., Bozek A., Bračko M., Brodzicka J., Chen A., Cheon B. G., Chistov R., Choi Y., Choi Y. K., Chuvikov A., Dalseno J., Danilov M., Dash M., Drutskoy A., Eidelman S., Enari Y., Epifanov D., Fratina S., Gabyshev N., Garmash A., Gershon T., Gokhroo G., Hayasaka K., Hayashii H., Hoshi Y., Hou S., Hou W. S., Iijima T., Imoto A., Inami K., Ishikawa A., Itoh R., Iwasaki M., Iwasaki Y., Kang J. H., Kang J. S., Kataoka S. U., Katayama N., Kawai H., Kawasaki T., Khan H. R., Kichimi H., Kim H. J., Kim J. H., Kim S. K., Kim S. M., Korpar S., Križan P., Krokovny P., Kulasiri R., Kuo C. C., Kuzmin A., Kwon Y. J., Leder G., Lee S. E., Lesiak T., Li J., Lin S. W., Liventsev D., Majumder G., Mandl F., Matsumoto T., Matyja A., Mitaroff W., Miyake H., Miyata H., Mizuk R., Mohapatra D., Mori T., Nagamine T., Nagasaka Y., Nakano E., Nakao M., Natkaniec Z., Nishida S., Nitoh O., Nozaki T., Ogawa S., Ohshima T.

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.