Fabian Bach, Thorsten Ohl
In an effective operator approach, the full set of leading contributions to anomalous top couplings comprises various new trilinear as well as higher interaction vertices, some of which are related to one another by gauge symmetry or equations of motion. In order to study trilinear top couplings to SM gauge bosons such as ttA, ttZ, tbW and ttg, the operator set can be restricted accordingly. However, the complete basis cannot be consistently mapped onto an on-shell parametrisation of the trilinear vertices alone. Four-fermion contact terms qqtt and udtb must be included if consistency is to be retained. In this paper, we point out how these interactions contribute to the single top search channels for anomalous trilinear tbW couplings at the LHC and Tevatron, thus affecting the corresponding bounds. All results are based on full leading order partonic matrix elements, thus automatically accounting for off-shell and interference effects as well as irreducible backgrounds. A discussion of the quantitative effects of going from on-shell to off-shell tops and applying acceptance cuts on the matrix elements is also provided.
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http://arxiv.org/abs/1209.4564
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