Charged Higgs Boson Search at the Tevatron Upgrade Using Tau(11)

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

there is a visible peak only at x′?0but not at x′?1.The reason is that the latter condition holds only for a tiny region of the phase space as we see from (50).The a1T decay distribution(47)vanishes near the collinear con?guration (52).It has maxima at

cosθa=0and cosθρ=±1or cosθρ=0,cosφρ=0(53) which correspond to the plane of the three decay pions in the a1rest frame being normal to its line of?ight.This results in an even sharing of the a1energy as in the case ofρT decay.In particular both the distributions vanish at the extrema x′=0and1and peak near the middle,although the a1T peak occurs a little below x′=0.5.Indeed the shapes of a1L and a1T decay distributions in x′are qualitatively similar to those ofρL andρT,except for the suppression of the x′?1peak for a1L.A comparison of these distributions can be found in[6]. There is reason to believe that the above features of longitudinal and transverse a1decay are insensitive to the assumed dynamical model[15].Indeed it follows from general considerations that the a1L(T)→3πdecay favours the plane of the3pions in the a1rest frame being coincident with(normal to)the a1line of ?ight[13].The role of the model is only to determine the distribution of energy among the3pions in this plane.Moreover as shown in[6],the alternative model of Isgur et al[16]gives very similar pion energy distributions as that of [15].

Thus the transverseρand a1decays favour even sharing of energy by the charged and neutral pions,while the longitudinalρand a1decays favour ex-treme con?gurations where the charged pion carries practically all or none of the vector meson energy.This can be exploited to suppress the former while retaining most of the latter contributions along with that of the pion(20).This will in turn enhance the H±signal to W±background ratio in the1-prong hadronic decay channel ofτas we shall see below.

4RESULTS AND DISCUSSION

We shall be interested in the inclusive1-prong hadronic decay ofτ,which is dominated by theπ±,ρ±and a±1contribution(20,21,22).It results in a thin 1-prong hadronic jet(τ-jet)consisting of a charged pion along with0,1or2π0s respectively.Since all the pions emerge in a collinear con?guration one can neither measure their invariant mass nor the number ofπ0s.Consequently it is not possible to identify the mesonic state.But it is possible to measure

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