Distinguishing a charged Higgs signal from a heavy

The generation o f accelerators currently under construction promises to enable physicists to probe various extensions o f the Standard Model (SM), including Supersymmetric and Left -Right Symmetric models. Each of these models introduces new groups o f presently-undetected particles, whose experimental signals must be distinguished from known SM processes. In the cases o f charged Higgs bosons ( H -+ ) and heavy right-handed Wbosons ( W~ ), two groups have independently demonstrated that the new bosons may be differentiated from SM W(80) backgrounds by examining polarization effects in tau-lepton decays: both the H -+ [1] and the W~ [2] are predicted to couple preferentially to right-handed z's, as opposed to the SM ( V A ) coupling W (80) --. ~2+ ~. Refs. [ 1,2 ] trace the effects of the z helicity on its ( n n ) decays. For example, in an n = 1 decay, zg --. n ~ , where ot is the z helicity, the single pion should be backward-scattered and soft ( x ~ 0 , where x = E J E ~ ) for a = L , but should be forward-scattered and hard (x--. 1 ) for a = R . In this way, a measure o f the z helicity, based on the energy spectrum of the final-state pion, may be used to isolate non-SM boson signals from z's parented by W(80) ' s . Further correlations can be constructed for n = 2, 3 decays via intermediate polarized vector mesons [ 1 ]. However, a problem which both refs. [ 1,2 ] fail to address is how to distinguish between H e and Wx~ : the final-state pion correlations would remain powerless to reveal the actual identity o f the new boson. Other proposed means of separating non-SM bosons from W(80) signals would similarly fail to distinguish between H -+ and WI~. It has been shown that the most important sub-process for H -+ production is gluon + b-quark fusion: gb--.H +t. Gunion et al. have argued that the signal-to-background ratio (S /B) for detection o f a charged Higgs boson in the (zv)-channel could be increased as much as 30 times against the W(80) background by correlating the r-decays with a trigger on the "spectator" t-quark semileptonic decays [ 3 ]. Such a "stiff lepton trigger" would weed out all SM events except for g b ~ W(80) t, which could be distinguished from the H -+ case by the (assumed) large mass difference between the H -+ and the W(80) . Yet such a mass-related cut could not separate H -+ from Wff signals: Gunion and company estimate that rows >/2.5 TeV would be required to differentiate a W~ signal from a mn+_ ~< 1 TeV signal [ 3 ]. Current limits on m WR are as low as 316 GeV [ 4], however, which places the Wff in precisely the same mass range as the H -+. Thus, although a stiff lepton trigger on spectator-t quark decays could highlight new non-SM bosons, it would be ineffective in distinguishing a charged Higgs signal from a heavy W signal. Clearly some further information is required to identify the parent boson in z decays. One difference between the H -+ and W~ concerns lepton-universality: the H -+ should violate universality, coupling preferentially to the heavy z, whereas the Wff should obey universality. Measurement of the WR mass in decays