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arXiv · 1508.06757

Study of $\pi^0$ pair production in single-tag two-photon collisions

The Belle Collaboration·M. Masuda·S. Uehara·Y. Watanabe·H. Nakazawa·A. Abdesselam·I. Adachi·H. Aihara·S. Al Said·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·V. Babu·I. Badhrees·A. M. Bakich·E. Barberio·P. Behera·B. Bhuyan·J. Biswal·A. Bobrov·G. Bonvicini·A. Bozek·M. Bračko·T. E. Browder·D. Červenkov·V. Chekelian·A. Chen·B. G. Cheon·K. Chilikin·R. Chistov·K. Cho·V. Chobanova·S. -K. Choi·Y. Choi·D. Cinabro·J. Dalseno·M. Danilov·N. Dash·J. Dingfelder·Z. Doležal·Z. Drásal·D. Dutta·S. Eidelman·D. Epifanov·H. Farhat·J. E. Fast·T. Ferber·B. G. Fulsom·V. Gaur·N. Gabyshev·A. Garmash·R. Gillard·R. Glattauer·Y. M. Goh·P. Goldenzweig·B. Golob·J. Haba·K. Hayasaka·H. Hayashii·X. H. He·W. -S. Hou·T. Iijima·K. Inami·A. Ishikawa·R. Itoh·Y. Iwasaki·I. Jaegle·D. Joffe·K. K. Joo·T. Julius·K. H. Kang·E. Kato·T. Kawasaki·D. Y. Kim·J. B. Kim·J. H. Kim·K. T. Kim·M. J. Kim·S. H. Kim·Y. J. Kim·B. R. Ko·S. Korpar·P. Križan·P. Krokovny·T. Kumita·A. Kuzmin·Y. -J. Kwon·J. S. Lange·D. H. Lee·I. S. Lee·C. Li·L. Li·Y. Li·J. Libby·D. Liventsev·P. Lukin·D. Matvienko·K. Miyabayashi·H. Miyata
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Abstract

We report a measurement of the differential cross section of $\pi^0$ pair production in single-tag two-photon collisions, $\gamma^* \gamma \to \pi^0 \pi^0$, in $e^+ e^-$ scattering. The cross section is measured for $Q^2$ up to 30 GeV$^2$, where $Q^2$ is the negative of the invariant mass squared of the tagged photon, in the kinematic range 0.5 GeV < W < 2.1 GeV and $|\cos \theta^*|$ < 1.0 for the total energy and pion scattering angle, respectively, in the $\gamma^* \gamma$ center-of-mass system. The results are based on a data sample of 759 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The transition form factor of the $f_0(980)$ and that of the $f_2(1270)$ with the helicity-0, -1, and -2 components separately are measured for the first time and are compared with theoretical calculations.

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The Belle Collaboration, M. Masuda, S. Uehara, Y. Watanabe, H. Nakazawa, A. Abdesselam, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, V. Babu, I. Badhrees, A. M. Bakich, E. Barberio, P. Behera, B. Bhuyan, J. Biswal, A. Bobrov, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, D. Červenkov, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, R. Chistov, K. Cho, V. Chobanova, S. -K. Choi, Y. Choi, D. Cinabro, J. Dalseno, M. Danilov, N. Dash, J. Dingfelder, Z. Doležal, Z. Drásal, D. Dutta, S. Eidelman, D. Epifanov, H. Farhat, J. E. Fast, T. Ferber, B. G. Fulsom, V. Gaur, N. Gabyshev, A. Garmash, R. Gillard, R. Glattauer, Y. M. Goh, P. Goldenzweig, B. Golob, J. Haba, K. Hayasaka, H. Hayashii, X. H. He, W. -S. Hou, T. Iijima, K. Inami, A. Ishikawa, R. Itoh, Y. Iwasaki, I. Jaegle, D. Joffe, K. K. Joo, T. Julius, K. H. Kang, E. Kato, T. Kawasaki, D. Y. Kim, J. B. Kim, J. H. Kim, K. T. Kim, M. J. Kim, S. H. Kim, Y. J. Kim, B. R. Ko, S. Korpar, P. Križan, P. Krokovny, T. Kumita, A. Kuzmin, Y. -J. Kwon, J. S. Lange, D. H. Lee, I. S. Lee, C. Li, L. Li, Y. Li, J. Libby, D. Liventsev, P. Lukin, D. Matvienko, K. Miyabayashi, H. Miyata. 2015-08-27. Study of $\pi^0$ pair production in single-tag two-photon collisions. https://doi.org/10.1103/physrevd.93.032003

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