General Tests for t ---> W+ b couplings at Hadron Colliders

Charles A. Nelson; Brian T. Kress; Marco Lopes; Thomas P. McCauley

doi:10.1103/PhysRevD.56.5928

paper

General Tests for t ---> W+ b couplings at Hadron Colliders

arXiv:hep-ph/9707211 · doi:10.1103/PhysRevD.56.5928

Abstract

The modularity property of the helicity formalism is used to provide amplitude expressions and stage-two spin-correlation functions which can easily be used in direct experimental searches for electro-weak symmetries and dynamics in the decay processes $t \to W^{+} b$ , $t ˉ \to W^{-} b ˉ$ . The formalism is used to describe the decay sequences $t \to W^{+} b \to (l^{+} ν) b$ , and $t \to W^{+} b \to (j_{d ˉ} j_{u}) b$ . Helicity amplitudes for $t \to W^{+} b$ are obtained for the most general $J_{b ˉ t}$ current. Thereby, the most general Lorentz-invariant decay-density-matrix for $t \to W^{+} b \to (l^{+} ν) b$ , or for $t \to W^{+} b \to (j_{d ˉ} j_{u}) b$ , is expressed in terms of eight helicity parameters and, equivalently, in terms of the structures of the $J_{b ˉ t}$ current. The parameters are physically defined in terms of partial-width-intensities for polarized-final-states in \newline $t \to W^{+} b$ decay. The full angular distribution for the reactions $q q ˉ$ and $g g \to t t ˉ \to (W^{+} b) (W^{-} b ˉ) \to ...$ can be used to measure these parameters. Since this adds on spin-correlation information from the next stage of decays in the decay sequence, such an energy-angular distribution is called a stage-two spin-correlation (S2SC) function.

Minor clarifications. Expressions for r_{+-}, rho_{+-}, and ξfor ( L + S-P) coupling corrected. 36 pages LaTex + Tables + 14 Figs

General Tests for t ---> W+ b couplings at Hadron Colliders

Abstract

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