Dimension-six CP-conserving operators of the third-family quarks and their effects on collider observables

摘要: We list all possible dimension-six CP-conserving SUc(3)xSU(L)(2)xU(Y)(1)-invariant operators involving the third-family quarks which could be generated by new physics at a higher scale. Expressions for these operators after electroweak gauge symmetry breaking and the induced effective couplings Wt(b) over bar, Xb(b) over bar, and Xt(t) over bar (X = Z, gamma,g, H) are presented. Analytic expressions for the tree level contributions of all these operators to the observables R-b and A(FB)(b) at CERN LEP I, sigma(e(+)e(-) --> ) and A(FB)(b) at LEP II, sigma(e(+)e(-) --> ) and A(FB)(t) at the Next Linear Collider (NLC). as well as sigma( --> + X) at the Fermilab Tevatron upgrade, are provided. The effects of these operators on different electroweak observables are discussed and numerical examples presented. Numerical analyses show that in the coupling region allowed by R-b and A(FB)(b) at LEP I, some of the new physics operators can still have significant contributions at LEP II, the Tevatron, and the NLC.