High-statistics measurement of neutral-pion pair production in two-photon collisions

S Uehara,H Kichimi,E Nakano,J S Lange,T E Browder,H Hayashii,Y Teramoto,C P Shen,Y Hoshi,I Adachi,M Shapkin,C H Wang,Y Sakai,M Iwasaki,Y Liu,Y Choi,A Drutskoy,I Tikhomirov,S Ogawa,H Ha,L S Peak,T Ohshima,N Katayama,M Starič,A Zupanc,Y I Kim,W T Chen,B Shwartz,M Bračko,P Pakhlov,Y Nagasaka,B G Cheon,O Zyukova,G Pakhlova,J Haba,C W Park,O Schneider,V Balagura,A Chen,P Krokovny,H Sahoo,S Eidelman,S Stanič,H Kawai,H Nakazawa,K Arinstein,B Golob,A Ishikawa,J B Singh,Y Miyazaki,K S Park,I Bedny,Y Yusa,K Miyabayashi,S L Olsen,K Senyo,S Okuno,G Varner,U Bitenc,H Aihara,R Itoh,S Korpar,V Zhulanov,S E Lee,D H Kah,K Belous,H Park,A Limosani,J Dalseno,D Epifanov,Z P Zhang,T Iijima,K Hayasaka,A Kuzmin,Y Watanabe,S Nishida,D Liventsev,Y J Kim,S Uno,Y Usov,P Križan,V Bhardwaj,J H Kang,P Urquijo,M E Sevior,C Liu,V Zhilich,Z Natkaniec,H Ozaki,R Kumar,L E Piilonen,J S Lee,R Wedd,H K Park,Y Unno,M Dash,M Nakao,A Sokolov,Y Yamashita,H J Kim,T Kawasaki,A Bay,P Wang,K Inami,E Won,I Nakamura,G N Taylor,A Bondar,T Sumiyoshi,S Mconie,O Nitoh,H J Hyun,X L Wang,W.-S Hou,F Mandl,T Uglov,A M Bakich,Shoji Suzuki ,S H Kyeong ,J G Shiu ,S W Lin ,H Pałka ,E L Barberio ,K F Chen ,Takashi Mori ,Y Kwon ,T Živko ,Hiroshi Kaji ,I S Cho ,M C Chang

doi:10.1103/physrevd.78.052004

Abstract

We present a high-statistics measurement of differential cross sections and the total cross section for the process γγ→π0π0 in the kinematic range 0.6 GeV≤W≤4.0 GeV and |cosθ*|≤0.8, where W and θ* are the energy and pion scattering angle, respectively, in the γγ center-of-mass system. Differential cross sections are fitted to obtain information on S, D0, D2, G0, and G2 waves. The G waves are important above W≃1.6 GeV. The general behavior of partial waves is studied by fitting differential cross sections in a simple parametrization where amplitudes contain resonant contributions and smooth background. The D2 wave is dominated by the f2(1270) meson whose parameters are consistent with the current world averages. The D0 wave contains a f2(1270) component, whose fraction is fitted. For the S wave, the f0(980) parameters are found to be consistent with the values determined from our recent π+π− data. In addition to the f0(980), the S wave prefers to have another resonance-like contribution whose parameters are obtained.5 MoreReceived 22 May 2008DOI:https://doi.org/10.1103/PhysRevD.78.052004©2008 American Physical Society

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