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S. Heinemeyer

Publications and source records attributed to S. Heinemeyer.

At least 163 records · Page 9Linked to original sources

Predictions for m_t and m_W in Minimal Supersymmetric Models

Using a frequentist analysis of experimental constraints within two versions of the minimal supersymmetric extension of the Standard Model, we derive the predictions for the top quark mass, m_t, and the W boson mass, m_W. We find that the supersymmetric predictions for both m_t and m_W, obtained by incorporating all the relevant experimental information and state-of-the-art theoretical predictions, are highly compatible with the experimental values with small remaining uncertainties, yielding an improvement compared to the case of the Standard Model.

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Higgs and Electroweak Physics

This lecture discusses the Higgs boson sector of the SM and the MSSM, including their connection to electroweak precision physics and the searches for SM and SUSY Higgs bosons at the LHC.

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SUSY Les Houches Accord 2

The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first SLHA to include various generalisations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavour, as well as the simplest next-to-minimal model.

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SUSY Les Houches Accord: Interfacing SUSY Spectrum Calculators, Decay Packages, and Event Generators

An accord specifying a unique set of conventions for supersymmetric extensions of the Standard Model together with generic file structures for 1) supersymmetric model specifications and input parameters, 2) electroweak scale supersymmetric mass and coupling spectra, and 3) decay tables is defined, to provide a universal interface between spectrum calculation programs, decay packages, and high energy physics event generators.

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Finite SU(3)^3 model

We consider N=1 supersymmetric gauge theories based on the group SU(N)_1 x SU(N)_2 x ... x SU(N)_k with matter content (N,N*,1,...,1) + (1,N,N*,..., 1) + >... + (N*,1,1,...,N) as candidates for the unification symmetry of all particles. In particular we examine to which extent such theories can become finite, and find that a necessary condition is that there should be exactly three families. From phenomenological considerations an SU(3)^3 model is singled out. We consider an all-loop and a two-loop finite model based on this gauge group and we study their predictions concerning the third generation quark masses.

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BSM Higgs Studies at the LHC in the Forward Proton Mode

The prospects for central exclusive diffractive (CED) production of BSM Higgs bosons at the LHC are reviewed. This comprises the production of MSSM and 4th generation Higgs bosons. The sensitivity of the searches in the forward proton mode for the Higgs bosons as well as the possibility of a coupling structure determination are briefly discussed.

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SUSY Predictions for the LHC

In the CMSSM we find preferences for sparticle masses that are relatively light. In the NUHM1 the best-fit values for many sparticle masses are even slightly smaller, but with greater uncertainties. We find that at the 95% C.L. all colored particles are in the reach of the LHC. While the light Higgs boson is bounded from above by M_h <= 125 GeV, the heavy Higgs bosons could well escape the LHC searches, but might be accessible at the ILC.

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New HiggsBounds from LEP and the Tevatron

We review the program HiggsBounds that tests theoretical predictions of models with arbitrary Higgs sectors against the exclusion bounds obtained from the Higgs searches at LEP and the Tevatron. We explicitly list the bounds that have been added after the first release of HiggsBounds.

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From the LHC to Future Colliders

Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300/fb of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10/fb of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.

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Mass Bounds on a Very Light Neutralino

Within the Minimal Supersymmetric Standard Model (MSSM) we systematically investigate the bounds on the mass of the lightest neutralino. We allow for non-universal gaugino masses and thus even consider massless neutralinos, while assuming in general that R-parity is conserved. Our main focus are laboratory constraints. We consider collider data, precision observables, and also rare meson decays to very light neutralinos. We then discuss the astrophysical and cosmological implications. We find that a massless neutralino is allowed by all existing experimental data and astrophysical and cosmological observations.

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Likelihood Functions for Supersymmetric Observables in Frequentist Analyses of the CMSSM and NUHM1

On the basis of frequentist analyses of experimental constraints from electroweak precision data, g-2, B physics and cosmological data, we investigate the parameters of the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking mass parameters, and a model with common non-universal Higgs masses (NUHM1). We present chi^2 likelihood functions for the masses of supersymmetric particles and Higgs bosons, as well as b to s gamma, b to mu mu and the spin-independent dark matter scattering cross section. In the CMSSM we find preferences for sparticle masses that are relatively light. In the NUHM1 the best-fit values for many sparticle masses are even slightly smaller, but with greater uncertainties. The likelihood functions for most sparticle masses are cut off sharply at small masses, in particular by the LEP Higgs mass constraint. Both in the CMSSM and the NUHM1, the coannihilation region is favoured over the focus-point region at about the 3-sigma level, largely but not exclusively because of g-2. Many sparticle masses are highly correlated in both the CMSSM and NUHM1, and most of the regions preferred at the 95% C.L. are accessible to early LHC running. Some slepton and chargino/neutralino masses should be in reach at the ILC. The masses of the heavier Higgs bosons should be accessible at the LHC and the ILC in portions of the preferred regions in the (M_A, tan beta) plane. In the CMSSM, the likelihood function for b to mu mu is peaked close to the Standard Model value, but much larger values are possible in the NUHM1. We find that values of the DM cross section > 10^{-10} pb are preferred in both the CMSSM and the NUHM1. We study the effects of dropping the g-2, b to s gamma, relic density and M_h constraints.

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Indirect Limits on Higgs and SUSY Masses

We review the current best fit values of Higgs boson masses in the Standard Model (SM) and its minimal supersymmetric extension (MSSM) obtained from existing experimental data. We also review the parameters space of the constrained MSSM (CMSSM) and the non-universal Higgs mass model (NUHM1) currently preferred by precision data. Following a Frequentist approach, the experimental data includes electroweak precision observables, B physics observables and the relic density of cold dark matter.

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HiggsBounds: Confronting arbitrary Higgs sectors with exclusion bounds from LEP and Tevatron

HiggsBounds is a computer code which tests the Higgs sectors of new models against the current exclusion bounds from the Higgs searches at LEP and the Tevatron. As input, it requires a selection of model predictions, such as Higgs masses, branching ratios, effective couplings and total decay widths. HiggsBounds then uses the expected and observed topological cross section limits from the Higgs searches to determine which points in the parameter space have already been excluded at 95% CL. HiggsBounds will be updated to include new results as they become available.

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Forward tracking at the next e+ e- collider part I: the physics case

In a series of notes we explore the detector requirements of the forward tracking region for a future $ e^+ e^- $ collider with a center-of-mass energy in the range from 500 GeV to 3 TeV. In this first part we investigate the relevance of the forward region for a range of physics processes that are likely to be relevant in such a machine. We find that many examples can be found where excellent performance of the forward detector system may lead to a considerable increase of the physics output of the experiment. A particularly clear physics case can be made for the reconstruction of electrons at small polar angle.

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The FP420 R&D Project: Higgs and New Physics with forward protons at the LHC

We present the FP420 R&D project, which has been studying the key aspects of the development and installation of a silicon tracker and fast-timing detectors in the LHC tunnel at 420 m from the interaction points of the ATLAS and CMS experiments. These detectors would measure precisely very forward protons in conjunction with the corresponding central detectors as a means to study Standard Model (SM) physics, and to search for and characterise New Physics signals. This report includes a detailed description of the physics case for the detector and, in particular, for the measurement of Central Exclusive Production, pp --> p + phi + p, in which the outgoing protons remain intact and the central system phi may be a single particle such as a SM or MSSM Higgs boson. Other physics topics discussed are gamma-gamma and gamma-p interactions, and diffractive processes. The report includes a detailed study of the trigger strategy, acceptance, reconstruction efficiencies, and expected yields for a particular p p --> p H p measurement with Higgs boson decay in the b-bbar mode. The document also describes the detector acceptance as given by the LHC beam optics between the interaction points and the FP420 location, the machine backgrounds, the new proposed connection cryostat and the moving ("Hamburg") beam-pipe at 420 m, and the radio-frequency impact of the design on the LHC. The last part of the document is devoted to a description of the 3D silicon sensors and associated tracking performances, the design of two fast-timing detectors capable of accurate vertex reconstruction for background rejection at high-luminosities, and the detector alignment and calibration strategy.

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Tools for Charged Higgs Bosons

In order to identify the Higgs sector realized in nature, the predictions for Higgs boson masses, production cross sections and decay widths have to be compared with experimental results. We give a brief overview about computer codes for the evaluation of the properties of charged Higgs bosons, mostly focusing on the case of the Minimal Supersymmetric Standard Model (MSSM). We briefly review the relevance of the various contributions to the charged MSSM Higgs boson mass arising at the one-loop level.

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Charged MSSM Higgs Bosons at CMS: Reach and Parameter Dependence

We review the analysis of the 5 sigma discovery contours for the charged MSSM Higgs boson at the CMS experiment with 30 fb^-1 for the two cases M_H+ < m_t and M_H+ > m_t. Latest results for the CMS experimental sensitivities based on full simulation studies are combined with state-of-the-art theoretical predictions of MSSM Higgs-boson production and decay properties. Special focus is put on the SUSY parameter dependence of the 5 sigma contours. The variation of mu can shift the prospective discovery reach in tan_beta by up to Delta tan_beta = 40. We furthermore discuss various theory uncertainties on the signal cross section and branching ratio calculations. In order to arrive at a reliable interpretation of a signal of the charged MSSM Higgs boson at the LHC a strong reduction in the relevant theory uncertainties will be necessary.

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