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preprints:2000:ttp00-16 [2016/03/17 11:03] (current)
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 +====== TTP00-16 Four Pion Final States with Tagged Photons at Electron Positron Colliders ====== 
 +   <​hidden TTP00-16 ​ Four Pion Final States with Tagged Photons at Electron Positron Colliders > A Monte Carlo generator has been constructed to simulate the reaction 
 + e^+ e^- \to \gamma + 4 \pi, where the photon is assumed to be observed 
 + in the detector. ​ Isospin relations between the amplitudes governing 
 + tau decays into four pions and electron positron annihilation into 
 + four pions respectively have been found which allow to determine all 
 + four modes after the amplitude for the \pi^+ \pi^- 2 \pi^0 channel has 
 + been fixed. ​ The kinematic breaking of these isospin relations as a 
 + ​consequence of the \pi^- -- \pi^0 mass difference has also been 
 + ​investigated. ​ The program is constructed in analogy to an earlier one 
 + ​simulating e^+ e^- \to \gamma + 2 \pi.  However, it does not include 
 + final state radiation from the charged pions. ​ Additional collinear 
 + ​photon radiation has been incorporated with the technique of structure 
 + ​functions. ​ Predictions are presented for cms energies of 1GeV, 3GeV 
 + and 10GeV, corresponding to the energies of DAPHNE, BEBC and of 
 + ​B-meson factories. ​ Using this program it is demonstrated that, even 
 + after applying realistic cuts, the event rates are sufficiently high 
 + to allow for a precise measurement of R(Q^2) in the region of Q 
 + ​between approximately 1GeV and 2.5GeV. ​ The model predictions are 
 + ​compared to recent data from electron positron colliders and agreement 
 + is obtained within the relatively large errors. 
 + </​hidden>​ 
 +|**H. Czyz and J.H. K\"​uhn** ​ |  
 +|**  Eur. Phys. J.  C 18 497-509 2001  **  | 
 +| {{preprints:​2000:​ttp00-16.pdf|PDF}} {{preprints:​2000:​ttp00-16.ps|PostScript}} [[http://​arxiv.org/​abs/​hep-ph/​0008262|arXiv]] ​  | 
 +| |