Abstract
An influence of the anomalous Wtb coupling on forward–backward asymmetry in top quark pair production at the Tevatron is investigated taking into account decays of the top quarks to 6 fermion final states containing one charged lepton. To this end the most general effective Lagrangian of the Wtb interaction containing terms of dimension up to five is implemented into carlomat, a general purpose Monte Carlo program, which allows to compute automatically all necessary cross sections in the presence of anomalous vector and tensor form factors. A sample of results which illustrate little effect of the left- and right-handed tensor form factors on the tt¯ invariant mass dependent forward–backward asymmetry and the charge-signed rapidity distribution of the lepton originating from the W boson from top quark decay is shown.
Highlights
The top quark is the heaviest particle ever observed, with mass close to the energy scale of the electroweak symmetry breaking
The top quark physics is an ideal place to look for non-standard effects which may reveal themselves through departures of the top quark properties and interactions from those predicted by the standard model (SM)
The observation of a forward–backward asymmetry (FBA) in the top quark pair production in high energy proton–antiproton collisions at Tevatron [1,2] that exceeds the SM expectation is an indication that this conjecture may be true
Summary
The top quark is the heaviest particle ever observed, with mass close to the energy scale of the electroweak symmetry breaking. Let us note that the Wtb coupling that is indicated by a black blob enters twice both in the ttproduction signal diagrams and the diagram with one top quark propagator It is not present in the off resonance background diagrams without internal top quark lines. It changes the total decay width of the top quark, which substantially alters the total cross sections of any of reactions (2) It changes the differential distributions of the final state particles, in particular of the final state lepton, which may have some influence on the ttproduction event reconstruction. In the present Letter, the anomalous Wtb coupling of the most general form, with operators up to dimension five, is included in the theoretical analysis in order to see to which extent its possible modifications may change lowest order SM predictions for the ttinvariant mass dependent FBA in the top quark pair production at the Tevatron. The question of whether the anomalous Wtb coupling may affect the asymmetry based on the charge and rapidity of the muon originating from the W boson from top quark decay will be addressed
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