High-statistics study of ηπ0 production in two-photon collisions

Uehara, S. ; Watanabe, Y. ; Nakazawa, H. ; Adachi, I. ; Aihara, H. ; Arinstein, K. ; Aulchenko, V. ; Bakich, A.M. ; Belous, K. ; Bondar, A. ; Bračko, M. ; Browder, T.E. ; Chang, P. ; Chen, A. ; Cheon, B.G. ; Chistov, R. ; Choi, Y. ; Crnkovic, J. ; Dalseno, J. ; Dash, M. ; Eidelman, S. ; Epifanov, D. ; Gabyshev, N. ; Garmash, A. ; Goldenzweig, P. ; Ha, H. ; Hayasaka, K. ; Hayashii, H. ; Horii, Y. ; Hoshi, Y. ; Hou, W.-S. ; Hyun, H.J. ; Iijima, T. ; Inami, K. ; Ishikawa, A. ; Itoh, R. ; Iwasaki, M. ; Iwasaki, Y. ; Kang, J.H. ; Kawai, H. ; Kichimi, H. ; Kiesling, C. ; Kim, H.O. ; Kim, J.H. ; Kim, Y.I. ; Kim, Y.J. ; Ko, B.R. ; Krokovny, P. ; Kumar, R. ; Kuzmin, A. ; Kwon, Y.-J. ; Kyeong, S.-H. ; Lee, S.-H. ; Li, J. ; Limosani, A. ; Liu, C. ; Liventsev, D. ; Louvot, R. ; Matyja, A. ; McOnie, S. ; Miyabayashi, K. ; Miyata, H. ; Miyazaki, Y. ; Mizuk, R. ; Mori, T. ; Nagasaka, Y. ; Nakano, E. ; Nakao, M. ; Nishida, S. ; Nishimura, K. ; Nitoh, O. ; Ogawa, S. ; Ohshima, T. ; Okuno, S. ; Palka, H. ; Park, C.W. ; Park, H. ; Park, H.K. ; Poluektov, A. ; Sahoo, H. ; Sakai, Y. ; Schneider, O. ; Schwanda, C. ; Senyo, K. ; Sevior, M.E. ; Shapkin, M. ; Shebalin, V. ; Shen, C.P. ; Shiu, J.-G. ; Shwartz, B. ; Singh, J.B. ; Sokolov, A. ; Stanič, S. ; Starič, M. ; Sumiyoshi, T. ; Taylor, G.N. ; Teramoto, Y. ; Unno, Y. ; Uno, S. ; Urquijo, P. ; Usov, Y. ; Varner, G. ; Vervink, K. ; Vinokurova, A. ; Wang, C.H. ; Wang, P. ; Wedd, R. ; Won, E. ; Yamashita, Y. ; Zhang, C.C. ; Zhang, Z.P. ; Zhilich, V. ; Zhulanov, V. ; Zivko, T. ; Zupanc, A. ; Zyukova, O.

The differential cross section for the process γγ→η π0 has been measured in the kinematic range 0.84GeV<W<4.0GeV, θ*|<0.8, where W and θ* are the energy and π0 (or η) scattering angle, respectively, in the γγ center-of-mass system. The results are based on a 223fb-1 data sample collected with the Belle detector at the KEKB e+e- collider. Clear peaks due to the a0(980) and a2(1320) are visible. The differential cross sections are fitted in the energy region 0.9GeV<W<1.46GeV to obtain the parameters of the a0(980). Its mass, width and ΓγγB(ηπ0) are measured to be 982.3-0.7-4.7+0.6+3. 1MeV/c2, 75.6±1.6-10.0+17.4MeV and 128-2-43+3+502eV, respectively. The energy and angular dependences above 3.1 GeV are compared with those measured in the π0π0 channel. The integrated cross section over θ*|<0. 8 has a W-n dependence with n=10.5±1.2±0.5, which is slightly larger than that for π0π0. The differential cross sections show a sin-4θ* dependence similar to γγ→π0π0. The measured cross section ratio, σ(ηπ0)/σ(π0π0)=0. 48±0.05±0.04, is consistent with a QCD-based prediction. © 2009 The American Physical Society.


Published in:
Physical Review D - Particles, Fields, Gravitation and Cosmology, 80, 3, 032001
Year:
2009
Keywords:
Other identifiers:
Scopus: 2-s2.0-69549095608
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 Record created 2010-11-05, last modified 2018-12-03


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