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 energy of the charged track as well as the total neutral energy,either by measuring the momentum of the former in the central detector and the total energy deposit in the EM and hadron calorimeters or from the showering pro?les in the EM and hadron calorimeters.Thus one has to develop a strategy to suppress the transverse vector meson contributions using these two pieces of information.We shall consider two such strategies below.In either case a rapidity and transverse energy cut of
|η|<2and E T>20GeV(54) with be applied on theτ-jet,where E T includes the neutral contribution.We shall use the recent structure functions of[17]for calculating the t¯t cross-section.
Firstly,we consider the e?ect of an isolation cut requiring the neutral E T accompanying the charged track within a cone of?R=(?η2+?φ2)1/2=0.2 to be
E ac T≡E0T<5GeV.(55) Fig.1shows the E ac T distribution for aτ-jet satisfying(54).Theπ,ρand a1 contributions are shown separately for the H±signal and the W±background, where we have chosen m H=80GeV and tanβ=1for illustrative purpose. The¯p p CM energy is taken to be2TeV.Several points are worth noting in this ?gure.
i)The signal to background ratio forπ(～4.5)is twice as large asρand thrice as large as a1.This is a consequence of the E T>20GeV cut and theτpolarization e?ect(24-29).
ii)Theρand a1contributions to the signal(background)are dominated by the longitudinal(transverse)components.
iii)Theρ±L→π±π0peak at x′?1shows up in the signal at E ac T?0while the x′?0peak is smeared over the large E ac T tail.The absence of a E ac T?0 peak in the a+1L→π±π0π0contribution to the signal re?ects the absence of a corresponding peak at x′?1as remarked earlier,while the x′?0peak is smeared over the large E ac T tail.
iv)Theρ±T→π±π0peak at x′?0.5shows up in the background at E ac T?15 GeV.The peak in the a±1T→π±π0π0contribution to the background at a somewhat higher E ac T re?ects the corresponding peak at x′somewhat below0.5 as remarked earlier.
As one sees from Fig.1,the isolation cut(55)on the charged track will es-sentially remove all the contributions except forπ±and a part of theρ±L→π±π0 corresponding to its x′?1peak,where the decayπ0is very soft.Consequently
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