14 research outputs found

    The LHC Inverse Problem, Supersymmetry and the ILC

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    We address the question whether the ILC can resolve the LHC Inverse Problem within the framework of the MSSM. We examine 242 points in the MSSM parameter space which were generated at random and were found to give indistinguishable signatures at the LHC. After a realistic simulation including full Standard Model backgrounds and a fast detector simulation, we find that roughly only one third of these scenarios lead to visible signatures of some kind with a significance {ge} 5 at the ILC with {radical}s = 500 GeV. Furthermore, we examine these points in parameter space pairwise and find that only one third of the pairs are distinguishable at the ILC at 5{sigma}

    Higgsless Electroweak Symmetry Breaking in Warped Backgrounds: Constraints and Signatures

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    We examine the phenomenology of a warped 5-dimensional model based on SU(2)L×_L \times SU(2)R×_R \times U(1)BL_{B-L} model which implements electroweak symmetry breaking through boundary conditions, without the presence of a Higgs boson. We use precision electroweak data to constrain the general parameter space of this model. Our analysis includes independent LL and RR gauge couplings, radiatively induced UV boundary gauge kinetic terms, and all higher order corrections from the curvature of the 5-d space. We show that this setup can be brought into good agreement with the precision electroweak data for typical values of the parameters. However, we find that the entire range of model parameters leads to violation of perturbative unitarity in gauge boson scattering and hence this model is not a reliable perturbative framework. Assuming that unitarity can be restored in a modified version of this scenario, we consider the collider signatures. It is found that new spin-1 states will be observed at the LHC and measurement of their properties would identify this model. However, the spin-2 graviton Kaluza-Klein resonances, which are a hallmark of the Randall-Sundrum model, are too weakly coupled to be detected.Comment: More detailed analysis, added references, 43 pages, 15 figures, LaTe

    TeV Mini Black Hole Decay at Future Colliders

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    It is generally believed that mini black holes decay by emitting elementary particles with a black body energy spectrum. The original calculation lead to the conclusion that about the 90% of the black hole mass is radiated away in the form of photons, neutrinos and light leptons, mainly electrons and muons. With the advent of String Theory, such a scenario must be updated by including new effects coming from the stringy nature of particles and interactions.By taking for granted that black holes can be produced in hadronic collisions, then their decay must take into account that: (i) we live in a D3-Brane embedded into an higher dimensional bulk spacetime; (ii) fundamental interactions, including gravity, are unified at TeV energy scale. Thus, the formal description of the Hawking radiation mechanism has to be extended to the case of more than four spacetime dimensions and include the presence of D-branes. Furthermore, unification of fundamental interactions at an energy scale many order of magnitude lower than the Planck energy implies that any kind of fundamental particle, not only leptons, is expected to be emitted. A detailed understanding of the new scenario is instrumental for optimal tuning of detectors at future colliders, where, hopefully, this exciting new physics will be tested. In this article we review higher dimensional black hole decay, considering not only the emission of particles according to Hawking mechanism, but also their near horizon QED/QCD interactions. The ultimate motivation is to build up a phenomenologically reliable scenario, allowing a clear experimental signature of the event.Comment: 22 pages, 9 figures, 4 tables; ``quick review'' for Class. and Quantum Gra

    The Discovery Potential of a Super B Factory

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    The Proceedings of the 2003 SLAC Workshops on flavor physics with a high luminosity asymmetric e+e- collider. The sensitivity of flavor physics to physics beyond the Standard Model is addressed in detail, in the context of the improvement of experimental measurements and theoretical calculations.Comment: 476 pages. Printed copies may be obtained by request to [email protected] . arXiv admin note: v2 appears to be identical to v

    Shedding Light on the Dark Sector with Direct WIMP Production

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    A Weakly Interacting Massive Particle (WIMP) provides an attractive dark matter candidate, and should be within reach of the next generation of high-energy colliders. We consider the process of direct WIMP pair-production, accompanied by an initial-state radiation photon, in electron-positron collisions at the proposed International Linear Collider (ILC). We present a parametrization of the differential cross section for this process which conveniently separates the model-independent information provided by cosmology from the model-dependent inputs from particle physics. As an application, we consider two simple models, one supersymmetric, and another of the "universal extra dimensions" (UED) type. The discovery reach of the ILC and the expected precision of parameter measurements are studied in each model. In addition, for each of the two examples, we also investigate the ability of the ILC to distinguish between the two models through a shape-discrimination analysis of the photon energy spectrum. We show that with sufficient beam polarization the alternative model interpretation can be ruled out in a large part of the relevant parameter space.Comment: 21 pages, 9 figure

    Simplified Models for LHC New Physics Searches

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    This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the "Topologies for Early LHC Searches" workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ~50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.Comment: 40 pages, 2 figures. This document is the official summary of results from "Topologies for Early LHC Searches" workshop (SLAC, September 2010). Supplementary material can be found at http://lhcnewphysics.or

    CP Studies and Non-Standard Higgs Physics

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    There are many possibilities for new physics beyond the Standard Model that feature non-standard Higgs sectors. These may introduce new sources of CP violation, and there may be mixing between multiple Higgs bosons or other new scalar bosons. Alternatively, the Higgs may be a composite state, or there may even be no Higgs at all. These non-standard Higgs scenarios have important implications for collider physics as well as for cosmology, and understanding their phenomenology is essential for a full comprehension of electroweak symmetry breaking. This report discusses the most relevant theories which go beyond the Standard Model and its minimal, CP-conserving supersymmetric extension: two-Higgs-doublet models and minimal supersymmetric models with CP violation, supersymmetric models with an extra singlet, models with extra gauge groups or Higgs triplets, Little Higgs models, models in extra dimensions, and models with technicolour or other new strong dynamics. For each of these scenarios, this report presents an introduction to the phenomenology, followed by contributions on more detailed theoretical aspects and studies of possible experimental signatures at the LHC and other colliders.Comment: Report of the CPNSH workshop, May 2004 - Dec 2005, 542 pages. The complete report as well as its individual chapters are also available from http://kraml.home.cern.ch/kraml/cpnsh/report.htm
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