Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below $t \bar t$ Threshold

Heath Pois; Thomas J. Weiler; Tzu Chiang Yuan

doi:10.1103/PhysRevD.47.3886

paper

Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below $t t ˉ$ Threshold

arXiv:hep-ph/9303277 · doi:10.1103/PhysRevD.47.3886

Abstract

The rare decay modes Higgs $\to$ four light fermions, and Higgs $\to$ single top-quark + three light fermions for $m_{t} < M_{H} < 2 m_{t}$ , are presented, and phenomenologically interpreted. The angular correlation between fermion planes is presented as a test of the spin and intrinsic parity of the Higgs particle. In Higgs decay to single top, two tree-level graphs contribute in the standard model (SM); one couples the Higgs to $W^{+} W^{-} (\sim g M_{W})$ , and one to $t\bar t(\sim g_{top\;yukawa}=m_t/246\GeV)$. The large Yukawa coupling for $m_t>100\GeV$ makes the second amplitude competitive or dominant for most $M_{H}, m_{t}$ values. Thus the Higgs decay rate to single top directly probes the SM universal mechanism generating both gauge boson and fermion masses, and offers a means to infer the Higgs- $t t ˉ$ Yukawa coupling when $H \to t t ˉ$ is kinematically disallowed. We find that the modes $pp \to X t t ˉ (H \to t b ˉ W^{(*)})$ at the SSC, and $e^{+} e^{-} \to Z or ν ν ˉ + (H \to t b ˉ W^{(*)})$ at future high energy, high luminosity colliders, may be measureable if $2 m_{t}$ is not too far above $M_{H}$ . We classify non-standard Higgses as gaugeo-phobic, fermio-phobic or fermio-philic, and discuss the Higgs $\to$ single top rates for these classes.

30 pages, 6 figures (figures available upon request); VAND-TH-93/4

Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below ttˉ Threshold

Abstract

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Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below $t t ˉ$ Threshold