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[en] Both Little Higgs and Higgsless Models provide new windows into the mysteries of electroweak symmetry breaking and lead to testable predictions at present and future colliders. Here we give a quick overview of three papers submitted to the ICHEP2004 meeting on these subjects
[en] Several new physics scenarios can lead to monojet signatures at the LHC. If such events are observed above the Standard Model background it will be important to identify their origin. In this paper we compare and contrast these signatures as produced in two very different pictures: vector or scalar unparticle production in the scale-invariant/conformal regime and graviton emission in the Arkani-Hamed, Dimopoulos and Dvali extra-dimensional model. We demonstrate that these two scenarios can be distinguished at the LHC for a reasonable range of model parameters through the shape of their respective monojet and/or missing ET distributions
[en] We explore the phenomenological implications at colliders for the existence of higher-curvature gravity as extensions to both the Randall-Sundrum(RS) and Arkani-Hamed, Dimopoulos and Dvali(ADD) scenarios. Such terms are expected to arise on rather general grounds from ultraviolet completions of General Relativity, e.g., from string theory. In the Randall-Sundrum model these terms shift the mass spectrum and couplings of the graviton tower. In the case of ADD they can lead to a threshold for the production of long-lived black holes
[en] We examine the phenomenological implications at colliders for the existence of higher-derivative gravity terms as extensions to the Randall-Sundrum model. Such terms are expected to arise on rather general grounds, e.g., from string theory. In 5-d, if we demand that the theory be unitary and ghost free, these new contributions to the bulk action are uniquely of the Gauss-Bonnet form. We demonstrate that the usual expectations for the production cross section and detailed properties of graviton Kaluza-Klein resonances and TeV-scale black holes can be substantially altered by existence of these additional contributions. It is shown that measurements at future colliders will be highly sensitive to the presence of such terms
[en] The methods which can be employed to determine the properties of new neutral resonant states that may be observed in the Drell-Yan channel at the LHC are reviewed. If these states are sufficiently light we discuss how polarized ep scattering at the LHeC can assist in the determination of their couplings to the Standard Model (SM) fermions
[en] We explore the physics of the general CP-conserving MSSM with Minimal Flavor Violation, the pMSSM. The 19 soft SUSY breaking parameters are chosen so to satisfy all existing experimental and theoretical constraints assuming that the WIMP is the lightest neutralino. We scan this parameter space twice using both flat and log priors and compare the results which yield similar conclusions. Constraints from both LEP and the Tevatron play an important role in obtaining our final model samples. Implications for future TeV-scale e+e- linear colliders (LC) are discussed
[en] Extra dimensions provide a new window on a number of problems faced by the Standard Model. The following provides an introduction to this very broad subject aimed at experimental graduate students and post-docs based on a lecture given at the 2004 SLAC Summer Institute
[en] We explore the possibility of indirectly observing the effects of Z(prime)-like particles with electroweak strength couplings in the Drell-Yan channel at the LHC with masses above the resonance direct search reach. We find that, mostly due to statistical limitations, this is very unlikely in almost all classes of models independently of the spin of the resonance. Not unexpectedly, the one exception to this general result is the case of degenerate Kaluza-Klein (KK) excitations of the photon and Z that occur in some extra-dimensional models. In this special case, the strong destructive interference with the Standard Model (SM) exchanges below the resonance mass leads to a well-known significant suppression of the cross section and thus increased sensitivity to this particular new physics scenario.
[en] It is possible to construct models based on warped extra dimensions in which electroweak symmetry breaking takes place without the introduction of any Higgs fields. This breaking can occur through the judiciuous choice of boundary conditions applied to gauge fields living in the bulk. One then finds that the fifth components of these bulk fields act as the Goldstone bosons, even for the would-be zero modes of the Kaluza-Klein tower. In this talk I will discuss the phenomenology of such scenarios, in particular, the problems associated with the construction of realistic models due to the simultaneous constraints imposed by precision electroweak data, present collider search limits and the requirement of perturbative unitarity in WL+WL- elastic scattering. Future collider signatures for such scenarios are also discussed
[en] The OPERA Collaboration has reported the observation of superluminal muon neutrinos, whose speed vv exceeds that of light c, with (vv-c)/c ≅ 2.5 x 10-5. In a recent work, Cohen and Glashow have refuted this claim by noting that such neutrinos will lose energy, by pair emission of particles, at unacceptable rates. Following the Cohen and Glashow arguments, we point out that pair emissions consistent with the OPERA anomaly can lead to detectable signals for neutrinos originating from decays of highly boosted top quarks at the LHC, allowing an independent test of the superluminal neutrino hypothesis.