96 research outputs found

    Supersymmetry

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    The determination of supersymmetric parameters at the LHC in favorable as well as difficult scenarios is presented. If discovered and measured at the LHC and the ILC, supersymmetry may provide a link between collider physics and cosmology.Comment: Invited talk at XVII International Workshop on Deep-Inelastic Scattering and Related Subjects DIS 2009, 26-30 April 2009, Madrid. 5 pages, 5 figure

    SFITTER: SUSY Parameter Analysis at LHC and LC

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    SFITTER is a new analysis tool to determine supersymmetric model parameters from collider measurements. Using the set of supersymmetric mass measurements at the LC and at the LHC we show how both colliders probe different sectors of the MSSM Lagrangian. This observation is a strong motivation to move from a parameter fit assuming a certain model to the unconstrained weak-scale MSSM Lagrangian. We argue how the technical challenges can be dealt with in a combined fit/grid approach with full correlations.Comment: contribution to LHC-LC Study Group, G.Weiglein et a

    Measuring Hidden Higgs and Strongly-Interacting Higgs Scenarios

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    Higgs couplings can be affected by physics beyond the Standard Model. We study modifications through interactions with a hidden sector and in specific composite Higgs models accessible at the LHC. Both scenarios give rise to congruent patterns of universal, or partially universal, shifts. In addition, Higgs decays to the hidden sector may lead to invisible decay modes which we also exploit. Experimental bounds on such potential modifications will measure the concordance of an observed Higgs boson with the Standard Model.Comment: 12 pages, 7 figures; version to be published in Phys. Lett.

    Extraction of SUSY Parameters from Collider Data

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    The extraction of the parameters of the supersymmetric Lagrangian is discusse d. Particular emphasis is put on the rigorous treatment of experimental and theo retical errors. While the LHC can provide a valuable first estimate of the parameters, the combination of LHC and ILC will be nece ssary to determine with high precision the parameters of the MSSM.Comment: 6 pages, 4 figures, Proceedings of plenary talk at SUSY08 in Seoul, Korea (typos corrected

    Measuring Higgs Couplings from LHC Data

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    Following recent ATLAS and CMS publications we interpret the results of their Higgs searches in terms of Standard Model operators. For a Higgs mass of 125 GeV we determine several Higgs couplings from 2011 data and extrapolate the results towards different scenarios of LHC running. Even though our analysis is limited by low statistics we already derive meaningful constraints on modified Higgs sectors.Comment: 5 pages, 4 figure

    Measuring Supersymmetry with Heavy Scalars

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    Supersymmetry with heavy scalars is a model where at the LHC we have to rely on rate measurements to determine the parameters of the underlying new physics. For this example we show how to properly combine rate measurements with kinematic endpoints, taking into account statistical, systematic and theory uncertainties. Provided we observe a sizeable number of events the LHC should be able to determine many model parameters with small enough error bars to for example test unification patterns.Comment: 13 pages, 8 table

    Measuring Higgs Couplings at a Linear Collider

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    Higgs couplings can be measured at a linear collider with high precision. We estimate the uncertainties of such measurements, including theoretical errors. Based on these results we show an extrapolation for a combined analysis at a linear collider and a high-luminosity LHC.Comment: 4 pages, 2 figures; v2: small text clarification, results unchanged, version to appear in EP

    Invisible Higgs Decays to Hooperons in the NMSSM

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    The galactic center excess of gamma ray photons can be naturally explained by light Majorana fermions in combination with a pseudoscalar mediator. The NMSSM provides exactly these ingredients. We show that for neutralinos with a significant singlino component the galactic center excess can be linked to invisible decays of the Standard-Model-like Higgs at the LHC. We find predictions for invisible Higgs branching ratios in excess of 50 percent, easily accessible at the LHC. Constraining the NMSSM through GUT-scale boundary conditions only slightly affects this expectation. Our results complement earlier NMSSM studies of the galactic center excess, which link it to heavy Higgs searches at the LHC.Comment: 23 pages, 24 figures; v2: references adde

    SFitter: Determining Supersymmetric Parameters

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    If supersymmetry (or a similar complex phenomenon) is found at the LHC, the goal for all colliders over the coming decades will be to extract the fundamental parameters of an underlying model from the measurements. Dedicated state-of-the-art tools will be necessary to link a wealth of measurements to an e.g. 20-dimensional MSSM parameter space. Starting from a general log- likelihood function of this high-dimensional parameter space we show how we can nd the best-fit parameter values and determine their errors. Beyond a single best-fit point we illustrate how distinct secondary minima occur in complex parameter spaces. In cases where there are at dimensions in the likelihood we comment on the bene ts and limitations of marginalizing over additional dimensions

    Constraining Supersymmetry using the relic density and the Higgs boson

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    Recent measurements by Planck, LHC experiments, and Xenon100 have significant impact on supersymmetric models and their parameters. We first illustrate the constraints in the mSUGRA plane and then perform a detailed analysis of the general MSSM with 13 free parameters. Using SFitter, Bayesian and Profile Likelihood approaches are applied and their results compared. The allowed structures in the parameter spaces are largely defined by different mechanisms of dark matter annihilation in combination with the light Higgs mass prediction. In mSUGRA the pseudoscalar Higgs funnel and stau co-annihilation processes are still avoiding experimental pressure. In the MSSM stau co-annihilation, the light Higgs funnel, a mixed bino--higgsino region including the heavy Higgs funnel, and a large higgsino region predict the correct relic density. Volume effects and changes in the model parameters impact the extracted mSUGRA and MSSM parameter regions in the Bayesian analysis
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