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Sven Heinemeyer

Publications and source records attributed to Sven Heinemeyer.

83 records · Page 5Linked to original sources
arXiv2011

Introducing HiggsBounds 2.0.0

We introduce version 2.0.0 of the computer program HiggsBounds. The program tests neutral and charged Higgs sectors of new models against the current exclusion bounds from 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. The program then uses the expected and observed topological cross section limits from the Higgs searches to determine whether a given parameter scenario of a model is excluded at the 95% C.L. by those searches. Version 2.0.0 includes 39/53 LEP/Tevatron Higgs search analyses, compared to 13/36 in the previous release (1.2.0). Among the newly included analyses are LEP searches for neutral Higgs bosons (H) decaying invisibly or into hadrons, LEP searches via the production modes (tau+ tau- H) and (b b-bar H), Tevatron searches via (t t-bar H), and LEP and Tevatron searches for charged Higgs bosons. Also, all Tevatron results presented at the ICHEP'10 are included in version 2.0.0. In this talk, we explain the basic ideas behind the implementation of HiggsBounds and provide a list of search topologies implemented in version 2.0.0. Furthermore, we apply HiggsBounds 2.0.0 to (a) determine the allowed Higgs mass range for a simple 4th generation model, (b) update/reproduce LEP/Tevatron Higgs exclusion plots for the MSSM m_h-max benchmark scenario, and (c) show exclusion results for the scalar sector of the Randall-Sundrum model.

hep-ph↗
arXiv2010

Probing the Higgs Sector of High-Scale SUSY-Breaking Models at the Tevatron

A canonical signature of the Minimal Supersymmetric Standard Model (MSSM) is the presence of a neutral Higgs boson with mass bounded from above by about 135 GeV and Standard Model (SM)-like couplings to the electroweak gauge bosons. In this note we investigate the reach of the Tevatron collider for the MSSM Higgs sector parameter space associated with a variety of high-scale minimal models of supersymmetry (SUSY)-breaking, including the Constrained MSSM (CMSSM), minimal Gauge Mediated SUSY-breaking (mGMSB), and minimal Anomaly Mediated SUSY-breaking (mAMSB). We find that the Tevatron can provide strong constraints on these models via Higgs boson searches. Considering a simple projection for the efficiency improvements in the Tevatron analyses, we find that with an integrated luminosity of 16 fb^-1 per detector and an efficiency improvement of 20% compared to the present situation, these models could be probed essentially over their entire ranges of validity. With 40% analysis improvements and 16 fb^-1, our projection shows that evidence at the 3-sigma level for the light Higgs boson could be expected in extended regions of parameter space.

hep-ph↗
arXiv2010

Finite Unification: Theory and Predictions

All-loop Finite Unified Theories (FUTs) are very interesting N=1 supersymmetric Grand Unified Theories (GUTs) which not only realise an old field theoretic dream but also have a remarkable predictive power due to the required reduction of couplings. The reduction of the dimensionless couplings in N=1 GUTs is achieved by searching for renormalization group invariant (RGI) relations among them holding beyond the unification scale. Finiteness results from the fact that there exist RGI relations among dimensionless couplings that guarantee the vanishing of all beta-functions in certain N=1 GUTs even to all orders. Furthermore developments in the soft supersymmetry breaking sector of N=1 GUTs and FUTs lead to exact RGI relations, i.e. reduction of couplings, in this dimensionful sector of the theory too. Based on the above theoretical framework phenomenologically consistent FUTS have been constructed. Here we present FUT models based on the SU(5) and SU(3)^3 gauge groups and their predictions. Of particular interest is the Higgs mass prediction of one of the models which is expected to be tested at the LHC.

hep-ph↗
arXiv2007

An Experiment to Search for Light Dark Matter in Low-Energy ep Scattering

Anomalous production of low-energy photons from the galactic center have fueled speculations on the nature and properties of dark matter particles. In particular, it has been proposed that light scalars may be responsible for the bulk of the matter density of the universe, and that they couple to ordinary matter through a light spin-1 boson. If this is the case, then such particles may be produced in the quasi-elastic low-energy scattering of electrons off protons. We present a proposal for an experiment to search for this process and assess its viability.

hep-ex↗
arXiv2004

The anomalous magnetic moment of the muon in the MSSM - recent developments

We present recent results of two interesting classes of supersymmetric two-loop contributions to (g-2)_mu. Two-loop diagrams involving either a closed sfermion loop or a closed chargino/neutralino loop can amount to 5*10^{-10}, which is almost one standard deviation of the current experimental uncertainty. We discuss the dependence of these two classes on the unknown supersymmetric parameters and their impact on the supersymmetric prediction of (g-2)_mu.

hep-ph↗
arXiv2004

Electroweak and supersymmetric two-loop corrections to (g-2)_μ

We present the up to now most precise evaluation of electroweak and supersymmetric contributions to the anomalous magnetic moment of the muon \amu, describing in detail also the calculational techniques. We calculate the bosonic two-loop contributions in the Standard Model without the approximation of a heavy Higgs-boson mass, finding corrections up to 0.2*10^{-10} for a light Higgs boson. In the Minimal Supersymmetric Standard Model the corresponding two-loop contributions from the two-Higgs-doublet model part differ from the Standard Model result by up to 0.3*10^{-10}. Finally, we evaluate the diagrams where a loop of charginos or neutralinos, the superpartners of gauge and Higgs bosons, is inserted into a two-Higgs-doublet one-loop diagram. These corrections can amount up to 10*10^{-10}, which is almost 2σof the current experimental uncertainty.

hep-ph↗
arXiv2003

Precision Observables in the MSSM: Status and Perspectives

The current status of the theoretical predictions for the electroweak precision observables M_W, sin^2_theta_eff and m_h within the MSSM is briefly reviewed. The impact of recent electroweak two-loop results to the quantity Delta_rho is analysed and the sensitivity of the electroweak precision observables to the top-quark Yukawa coupling is investigated. Furthermore the level of precision necessary to match the experimental accuracy at the next generation of colliders is discussed.

hep-ph↗
arXiv2002

Two-Loop Results for M_W in the Standard Model and the MSSM

Recent higher-order results for the prediction of the W-boson mass, M_W, within the Standard Model are reviewed and an estimate of the remaining theoretical uncertainties of the electroweak precision observables is given. An updated version of a simple numerical parameterisation of the result for M_W is presented. Furthermore, leading electroweak two-loop contributions to the precision observables within the MSSM are discussed.

hep-ph↗
arXiv2002

Precision Analysis of the Lightest MSSM Higgs Boson at Future Colliders

We investigate the sensitivity of observables measurable in e^+ e^-, gamma gamma and mu^+ mu^- collisions for distinguishing the properties of the light neutral CP-even Higgs boson in the minimal supersymmetric extension of the Standard Model (MSSM) from those of a Standard Model (SM) Higgs boson with the same mass. We explore first the available parameter space in the constrained MSSM (CMSSM), with universal soft supersymmetry-breaking parameters, incorporating the most recent direct limits on sparticle and Higgs masses, the indirect constraints from b to s gamma and g_mu - 2, and the cosmological relic density. We calculate the products of the expected CMSSM Higgs production cross sections and decay branching ratios sigma X B normalized by the corresponding values expected for those of a SM Higgs boson of the same mass. The results are compared with the precisions expected at each collider, and allow for a direct comparison of the different channels. The measurements in the Higgs sector are found to provide important consistency tests of the CMSSM. We then generalize our analysis to the case of a non-universal Higgs model (NUHM), where the values of M_A and mu are independent parameters. We explore in particular the sensitivity to M_A, finding that measurements at e^+ e^-, gamma gamma and mu^+ mu^- colliders could yield indirect constraints on its value, up to M_A ~ 1200 GeV. We discuss the potential of these measurements for distinguishing between the CMSSM and the NUHM, probing in this way the assumption of universality.

hep-ph↗
arXiv2001

GigaZ: High Precision Tests of the SM and the MSSM

The high-energy lepton collider TESLA can be operated in the GigaZ mode on the Z resonance, producing a billion Z bosons per year. This will allow the measurement of the effective electroweak mixing angle to an accuracy much better than one part in 10,000. Similarly, the W boson mass is expected to be measurable with an error of 6 MeV near threshold. We discuss the impact of these observables on the accuracy with which the Higgs boson mass can be determined from loop corrections within the Standard Model. We also study indirect constraints on new mass scales within the Minimal Supersymmetric Standard Model.

hep-ph↗