Low energy probes of standard model extensions.

摘要

Studies of low energy probes of higher theories that imbed or extend the standard model are performed. Experimentally, direct observation of definitive signatures of such models are, in general, not possible within the foreseeable future. However, some phenonema, directly or indirectly observed, may persist at accessible energies. In most cases, detection of such low energy phenonema will ambiguously point to classes of correct possible theoretical models. Here, such models are constrained by past, present, and future experiments.;Minimal supersymmetry imposed upon the standard model permits a neutralino cold dark matter candidate (CDM). The characteristics of the neutralmos are fingerprints of supersymmetry breaking mediation mechansims. Neutralinos that are mostly wino or higgsino are shown to be compatible with the 2000 DAMA annual modulation signal. We also present calculations for their predicted scattering rate with Germanium detectors.;A non-supersymmetric LFV Z' boson may mimic some of the phenomena usually attributed to supersymmetric theories. Constructing a conservative model of LFV Z' bosons, the recent BNL E821 muon g-2 deviation allows for a LFV Z' interpretation with a boson mass up to 4.8 TeV while staying within limits set by muon conversion, mu → egamma, and mu → eee. We calculate the experimental limits on the Z' mass and couplings that are placed by all relevant muon observables. Furthermore, the next linear collider is shown to be highly complementary with muon conversion experiments, which are shown to provide the strictest and most relevant bounds on LFV phenomena.;Finally, attention is called to potentially dangerous lepton flavor violation (LFV) induced by the D-terms of additional U(1) flavor-dependent gauge symmetries in supersymmetric models. In such models, LFV persists despite an arbitrarily high scale for the U(1) breaking and despite arbitrarily small gauge couplings. Taking into account the recent muon g-2 measurement, strong bounds are calculated for the magnitude of the D-term-induced LFV. Using current data we find that the lepton mass-mixing parameter &parl0;m2l&d5;L &parr0;12/m2l&d5; L is required to be less than O(10 -4)---a value perhaps already too low compared to expectations.