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arXiv · 1307.7457

High-statistics study of K^0_S pair production in two-photon collisions

Abstract

We report a high-statistics measurement of the differential cross section of the process gamma gamma --> K^0_S K^0_S in the range 1.05 GeV <= W <= 4.00 GeV, where W is the center-of-mass energy of the colliding photons, using 972 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider operated at and near the Upsilon-resonance region. The differential cross section is fitted by parameterized S-, D_0-, D_2-, G_0- and G_2-wave amplitudes. In the D_2 wave, the f_2(1270), a_2(1320) and f_2'(1525) are dominant and a resonance, the f_2(2200), is also present. The f_0(1710) and possibly the f_0(2500) are seen in the S wave. The mass, total width and product of the two-photon partial decay width and decay branching fraction to the K bar{K} state Gamma_{gamma gamma}B(K bar{K}) are extracted for the f_2'(1525), f_0(1710), f_2(2200) and f_0(2500). The destructive interference between the f_2(1270) and a_2(1320) is confirmed by measuring their relative phase. The parameters of the charmonium states chi_{c0} and chi_{c2} are updated. Possible contributions from the chi_{c0}(2P) and chi_{c2}(2P) states are discussed. A new upper limit for the branching fraction of the P- and CP-violating decay channel eta_c --> K^0_S K^0_S is reported. The detailed behavior of the cross section is updated and compared with QCD-based calculations.

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The Belle Collaboration, S. Uehara, Y. Watanabe, H. Nakazawa, I. Adachi, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, A. M. Bakich, A. Bala, V. Bhardwaj, B. Bhuyan, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, V. Chekelian, A. Chen, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, K. Cho, V. Chobanova, S. -K. Choi, Y. Choi, D. Cinabro, J. Dalseno, J. Dingfelder, Z. Doležal, D. Dutta, S. Eidelman, D. Epifanov, H. Farhat, J. E. Fast, M. Feindt, T. Ferber, A. Frey, V. Gaur, N. Gabyshev, S. Ganguly, R. Gillard, F. Giordano, Y. M. Goh, B. Golob, J. Haba, K. Hayasaka, H. Hayashii, Y. Hoshi, W. -S. Hou, H. J. Hyun, T. Iijima, A. Ishikawa, R. Itoh, Y. Iwasaki, T. Julius, D. H. Kah, J. H. Kang, E. Kato, H. Kawai, T. Kawasaki, C. Kiesling, D. Y. Kim, H. O. Kim, J. B. Kim, J. H. Kim, Y. J. Kim, J. Klucar, B. R. Ko, P. Kodyš, S. Korpar, P. Križan, P. Krokovny, T. Kumita, A. Kuzmin, Y. -J. Kwon, S. -H. Lee, J. Li, Y. Li, C. Liu, Z. Q. Liu, D. Liventsev, P. Lukin, D. Matvienko, K. Miyabayashi, H. Miyata, R. Mizuk, A. Moll, T. Mori, N. Muramatsu, R. Mussa, Y. Nagasaka, M. Nakao, C. Ng, N. K. Nisar, S. Nishida, O. Nitoh, S. Ogawa, S. Okuno. 2013-12-03. High-statistics study of K^0_S pair production in two-photon collisions. https://doi.org/10.1093/ptep%2Fptt097

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