We explore the prospect of charged Higgs boson search in top quark decay at the Tevatron collider upgrade, taking advantage of the opposite states of $\tau$ polarization resulting from the $H^\pm$ and $W^\pm$ decays. Methods of distinguishing the two contr
the decay pions.In order to use this feature,one must ?rst transform the polarization states of the vector meson appearing in (25,26)from the τrest frame to the laboratory frame.This is done by a Wigner rotation of the vector meson spin quantization axis
[14],i.e.
M ′λτλ′v = λv d 1λ′v λv (ω)M λτλv (30)
where the decay helicity amplitudes on the left and right correspond to the laboratory and the τrest frames respectively;and
cos ω=(m 2τ?m 2v )+(m 2τ+m 2v )cos θ
Γv
d Γlab vL
2m 2v
m 2v
cos 2ω+P τcos θ m τm 2v
cos 2ω?sin 2ω (32)1
d cos θ=1m 2τ+2m 2v 1+cos 2ω+
m 2τm 2v sin 2ω?
m τ
m 2τ 2 1+2m 2
m 2?m 2v +im Γv (m 2)(35)is the vector meson propagator with invariant mass m 2and the running width
Γv (m 2)=Γv
m f v (m 2v ).(36)7