In minimal SUSY-GUT models with M SU SY < ∼ 1 TeV, the renormalization group equations have a solution dominated by the infrared fixed point of the top Yukawa coupling. This fixed point predicts m t ≃ (200 GeV) sin β; combined with the LEP results it excludes m t < ∼ 130 GeV. For m t in the range 130-160 GeV, it predicts that the lightest scalar h has mass 60-85 GeV (detectable at LEP II). At SSC/LHC, each of the five scalars h, H, A, H ± may be detectable, but not all of them together; in one parameter region none would be detectable. * Talk presented by V. Barger at Hawaii LCWS (April, 1993).

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The expected trilepton signals from pp -+ X: Xg -+ (X~L*v)(X~L1+~'-) will be converted into hadronically quiet multilepton signals, if the two final Xy have leptonic R-parity-violating (RPV) decays X! -+ LC1v. We make illustrative calculations of the acceptance for these spectacular RPV signals, and point out that distinctive multilepton signals are possible even when the R-conserving trilepton signals are blocked by the "spoiler mode" Xg -+ hoX:. Other channels such as pp -+x: x: -+ ( X~~* v ) ( X~v v ) , pp -+ XtXy -+ (XyLv)X~r and f i -+ X: X; -+ (xye+v)(x!L1-v) can also give quiet multileptons from RPV. We investigate these signals in the context of supersymmetric models with radiative electroweak symmetry breaking, using examples in the low-tan P At fixed-point region.PACS number(s): 12.60. Jv, 13.85.Qk, 14.80.Ly There is intense interest in searching for signatures of supersymmetry (SUSY) a t the Fermilab Tevatron pjj collider, where the highest present cm energy f i = 1.8-2 TeV is accessed. An important possibility is the pair production of charginos and neutralinos [I], whose leptonic decay modes lead to many signatures [2-61. Recently, much theoretical [3,6] and experimental [7,8] attention has centered on trileptons from the production-and/or decay sequence Here and Xy are charginos and neutralinos (i, j denote mass ordering) and X: is the lightest SUSY particle (LSP) ; see Figs. l(a) and 1 (b). These trilepton events are distinctively "quiet" (little accompanying hadronic excitation); measurable rates are predicted for interesting ranges of SUSY parameters, but are lost in certain parameter regions, e.g., where the "spoiler mode" x; + xyh is kinematically accessible and suppresses all other X; de-FIG. 1. Representative diagrams for (a) the pair production of charginos and neutralinos, (b) their RPC decay, and (c) the RPV decay of the lightest neutralino.cays (h being the lightest Higgs scalar), or where one of the leptons is constrained to be soft and becomes undetectable [3,6].The popular scenario above assumes the LSP is stable and therefore practically invisible, due to R-parity conservation (RPC). The picture changes dramatically with R-parity violation (RPV) [9]. In particular, if explicit RPV occurs through L~L~E~ terms in the superpotential, the LSP will decay via X: + eelv to a neutrino plus two charged leptons that may have different flavors [see Fig. l(c)], thus converting the RPC trilepton signal into multileptons [lo] with up to seven charged l e p tons appearing in the final state. Even when the spoiler mode is active, suppressing RPC trileptons, a total of five charged leptons are still present in the decay of X: X;with RPV. Also, the channels xFX; + (Xye'v)(X~vv),x: x: -+ (x:ev)x:, or x: x; ' (x?e+")(x:e1-v) give quiet signals with up to five or six leptons. The actual multiplicity of observed leptons depends on the experimental thresholds and angular acceptances; in the present paper we give some sample calculations illustrating the high visibility of these multilepton signals.In th...

Abstract. We summarize the potential of muon colliders to probe fundamental physics. W + W − ,tt, and Zh threshold measurements could determine masses to precisions ∆M W = 6 MeV, ∆m t = 70 MeV, and ∆m h = 45 MeV, to test electroweak radiative corrections. With s-channel Higgs production, unique to a muon collider, the Higgs mass could be pinpointed (∆m h < 1 MeV) and its width measured. The other Higgs bosons of supersymmetry can be produced and studied by three methods. If instead the W W sector turns out to be strongly interacting, a 4 TeV muon collider is ideally suited to its study. I INTRODUCTIONIn this report we address the exciting physics that could be accomplished at muon colliders in the context of the central physics issue of our time: how is the electroweak symmetry broken, weakly or strongly? Higgs bosons and a low energy supersymmetry (SUSY) are the particles of interest in the weakly broken scenario and new resonances at the TeV scale of a new strong interaction dynamics are the alternatives.Muon colliders would have decided advantages over other machines in providing (i) sharp beam energy for precision measurements of masses, widths and couplings of the Higgs, W , t and supersymmetry particles, and (ii) high energy / high luminosity for production of high mass particles and studies of a strongly interacting electroweak sector (SEWS).In order to be able to do interesting physics at a muon collider, the minimum luminosity requirement is * ) Talk presented by V.