Irreducible QCD backgrounds to top searches in semi-leptonic final states at the Next Linear Collider

  • S. Moretti
Theoretical physics


At future electron-positron colliders, one of the largest irreducible backgrounds to top searches in the channel ‘4 jets + lepton + missing energy’ comes from QCD events of order \(\alpha_s^2\). We compute here such processes exactly at the parton level by resorting to 2 \(\to\) 6 matrix elements exploiting helicity amplitude techniques. We adopt a typical selection procedure based on the tagging of a high momentum and separated lepton. We finally outline kinematic differences between signal and background events that can be exploited to further reduce such a QCD noise.


Matrix Element Selection Procedure Background Event High Momentum Helicity Amplitude 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • S. Moretti
    • 1
  1. 1.Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK (e-mail: GB

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