Model SSC LHC

We explore the possibility that Z ′ couplings can be probed using decay modes which involve neutrinos once Standard Model backgrounds are directly determined by the data itself. For some models, sufficient statistics are available at either the SSC or LHC to render these modes useful for coupling determina-tions, provided the mass of the Z ′ is not much larger than 1 TeV, if we assume other new physics background sources are absent. If a new neutral gauge boson, Z ′ , is discovered at the SSC or LHC, an immediate goal will be the determination of its couplings to fermion pairs. Knowledge of these couplings will allow us to ascertain the extended electroweak model from which the Z ′ has originated. At an e + e − collider, such as LEP, the SLC, or the NLC, this is a relatively straightforward procedure that has already been successfully employed for the Standard Model (SM) Z. Performing a similar task in the hadron supercollider environment is far from easy and has prompted much activity in the theoretical and detector development arenas during the past three years 1. All of the techniques suggested in Ref. 1 are somewhat limited in scope so that new tools are continuously being sought to aid in the determination of Z ′ couplings at hadron supercolliders. In this report we outline some preliminary results from an analysis of Z ′ decay modes which involve neutrinos. As is always the case, the greatest difficulty in the use of missing E t or p t final states is the size of the SM backgrounds. In the two cases examined here, however, we may be able to employ the data itself to precisely determine these backgrounds. To be as specific as possible, we limit our discussion to only a few extended gauge models: (i) the Left-Right Symmetric Model (LRM) 2 , (ii) the Alternative Left-Right Model (ALRM) 3 , (iii) a model where the Z ′ couples exactly like the SM Z (SSM), and (iv) the E 6-inspired Effective Rank-5 Model (ER5M) 4. In the latter example, the model contains an additional parameter, θ, which lies in the range −90 • < θ < 90 •. Specific choices of this parameter correspond to special models discussed in the literature, i.e., ψ(θ = 0 •), χ(θ = −90 •), and η(θ = 37.76 •). Our first analysis concerns the quantity r …