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| 3 | == The BZ angle in e+ e- -> 4jets: abelian vs non-abelian == |

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| 5 | Use MadGraph/MadEvent to produce two event samples, |

| 6 | one for standard QCD and one with an abelian QCD model for |

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| 10 | Run the collision on the peak of the Z boson and set a minimum invariant mass |

| 11 | for the jets of %$m_{jj}>10$% GeV. Plot the |

| 12 | Bengtsson-Zerwas angle between the planes identified by the two lowest and to highest |

| 13 | energy jets: |

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| 15 | %$ |

| 16 | \cos \chi_{BZ} = |

| 17 | \frac{( {\bf p}''1\times {\bf p}''2) \cdot ({\bf p}''3\times {\bf p}''4)} |

| 18 | {||{\bf p}''1 \times {\bf p}''2 || ||{\bf p}''3\times {\bf p}''4||}\,. |

| 19 | $% |

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| 21 | Comparison should be made with the plots of Ref. [http://arxiv.org/abs/hep-ph/9503354 hep-ph/9503354], |

| 22 | where various implementation of the abelian models are discussed. Our web implementation include the emission of abelian gluons as possible partons leading to jets. |

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| 25 | -- Main.FabioMaltoni - 29 Aug 2007 |

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