Institute for Theoretical Particle Physics (TTP)

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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 ====== 
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 +   <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]]   | 
 +| |