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

K. Whisnant; Jin Min Yang; Bing-Lin Young; X. Zhang

doi:10.1103/PhysRevD.56.467

paper

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

arXiv:hep-ph/9702305 · doi:10.1103/PhysRevD.56.467

Abstract

We list all possible dimension-six CP-conserving $S U_{c} (3) \times S U_{L} (2) \times U_{Y} (1)$ 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 $W t b ˉ$ , $X b b ˉ$ and $X t t ˉ$ $(X = Z, γ, g, H)$ are presented. Analytic expressions for the tree level contributions of all these operators to the observables $R_{b}$ and $A_{F B}^{b}$ at LEP I, $σ (e^{+} e^{-} \to b b ˉ)$ and $A_{F B}^{b}$ at LEP II, $σ (e^{+} e^{-} \to t t ˉ)$ and $A_{F B}^{t}$ at the NLC, as well as $σ (p p ˉ \to t b ˉ + X)$ at the 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 $A_{F B}^{b}$ at LEP I, some of the new physics operators can still have significant contributions at LEP II, the Tevatron and the NLC.

25 pages

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

Abstract

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