Detecting Fermion Anomalous Electroweak Couplings At Colliders

The effective Lagrangian,based on the effective field theory,provides a modelindependent approach to new physics beyond the Standard Model.The coefficients of high-dimensional operators,i.e.anomalous couplings,can parameterize the low-energy effects of new physics.Previous studies mainly focused on Higgs and gauge sectors,while paid little attention to fermions.So this work mainly focus on the anomalous electroweak couplings of fermions.With a complete set of S U(3)c×S U(2)L ×U(1)Y invariant,CP-even dimension-six effective operators consisting of fermions and electroweak gauge bosons,we calculate the effects of anomalous couplings on different processes,especially high-energy processes at colliders.This work is supposed to provide good complementarities and extensions for anomalous coupling researches.For lepton anomalous electroweak couplings,we first study possible bounds from existing electroweak precision tests.We calculate the deviations from the Standard Model predictions in e~+e~-? W+W-process at the LEP,and in W/Z leptonic decay width.Assuming that the relative deviations can be no more than 5%,we derive bounds on these anomalous couplings,and the results are of O(0.1-1)TeV-2.We further study the abilities to detect these couplings at future?s = 500 GeV and?s = 1 TeV ILC,and with valid cos ? cuts we derive bounds of O(0.01-0.1)TeV-2.For quark anomalous electroweak couplings,we mainly study bounds from 8 TeV and 14 TeV LHC experiments.We calculate the deviations in pp ? W+W-and complemental pp ? ZZ/Z?/?? process.By analyzing the kinematic distributions of anomalous signals,we find additional cuts to improve detection sensitivities,and assuming that the relative deviations can be no more than 20% we finally derive bounds of O(0.1-1)TeV-2.Processes that only contain anomalous triple vertices,like pp ? W*? l? or pp ? Z*/?*? l+l-,can further improve the sensitivities to O(0.01-0.1)TeV-2.We then briefly discuss the possibilities to disentangle the effects of different anomalous couplings,and introduce the ?2function to quantize the kinematic differences between different anomalous couplings.