Fonctionne avec Indico
v3.2.8
The Standard Model (SM) of particle physics, based on the SU(3)_C × SU(2)_L × U(1)_Y gauge group, is an extremely successful theory that accounts for a wide range of high energy experiments at both the intensity and energy frontiers. Nevertheless it is widely believed to be incomplete, and manifestations of new physics are awaited to show up around the TeV scale. The unification of the SM gauge group in a larger, simple group, is theoretically very attractive. In this view, the SM is seen as an effective model valid at low energies. Thus, given the fact that the possible unification groups have a rank larger than the SM, additional subgroups like a U(1) or a second SU(2) may appear at intermediate stage when the unification group is broken down to the SM group. Interestingly, a new U(1) group factor predicts one additional gauge boson denoted Z′ in the literature. On the other hand, since SU(2) is a non-abelian group with three generators, an additional one leads to three gauge bosons of which one is neutral and two are charged and denoted W′± . In this thesis, we perform a calculation of electroweak top-quark pair hadroproduction in extensions of the SM with extra heavy neutral and charged spin-1 resonances. In particular, we allow for flavour-non-diagonal Z' couplings and take into account non-resonant production in the SM and beyond including the contributions with t-channel W and W′ bosons. We include NLO QCD corrections and consistently match to parton showers with the POWHEG method fully taking into account the interference effects between SM and new physics amplitudes. We present numerical results for top-pair cross sections at hadron colliders with a centre-of-mass energy up to 100 TeV. Subsequently we link our calculation to Contur, to obtain exclusion limits on the parameter space of models with extra heavy gauge bosons in the top-pair channel using real particle level data from the LHC.
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Meeting ID: 940 3914 2359
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