arXiv subjects

H. Rzehak

Publications and source records attributed to H. Rzehak.

At least 37 records · Page 2Linked to original sources

arXiv2011

Analysis of the NMSSM Higgs Boson Masses at One-Loop Level

For a reliable prediction of the NMSSM Higgs boson signatures at present and future high-energy colliders and a proper distinction of the NMSSM and MSSM Higgs sector the precise knowledge of the Higgs boson masses including higher-order corrections is indispensable. In this paper, the one-loop corrections to the neutral NMSSM Higgs boson masses and mixings are calculated in three different renormalisation schemes. In addition to the $\bar{DR}$ renormalisation scheme, existing in the literature, two other schemes are adopted. Furthermore, the dependence on the value of the top quark mass is investigated. The resulting Higgs mass corrections have been compared and the residual theory error due to missing higher-order corrections can be estimated to be of the order of 10%.

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arXiv2011

Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables

This Report summarizes the results of the first 10 months' activities of the LHC Higgs Cross Sections Working Group. The main goal of the working group was to present the status-of-art on Higgs Physics at the LHC integrating all new results that have appeared in the last few years. The Report is more than a mere collection of the proceedings of the general meetings. The subgroups have been working in different directions. An attempt has been made to present the first Report from these subgroups in a complete and homogeneous form. The subgroups' contributions correspondingly comprise the main parts of the Report. A significant amount of work has been performed in providing higher-order corrections to the Higgs-boson cross sections and pinning down the theoretical uncertainty of the Standard Model predictions. This Report comprises explicit numerical results on total cross sections, leaving the issues of event selection cuts and differential distributions to future publications. The subjects for further study are identified.

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arXiv2010

Consistent Higher-Order Corrections to Stop_i -> Sbottom_j H^+ in the Complex MSSM

We review an analysis of a consistent renormalization of the top and bottom quark/squark sector of the MSSM with complex parameters (cMSSM). Various renormalization schemes are defined, analyzed analytically and tested numerically in the decays Stop_2 -> Sbottom_i H^+/W^+ (i = 1,2). No scheme is found that produces numerically acceptable results over all the cMSSM parameter space, where problems occur mostly already for real parameters. Some numerical examples for Gamma(Stop_2 -> Sbottom_1 H^+) in our preferred scheme, "m_b, A_b DRbar" are shown.

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arXiv2010

NLO QCD corrections to $W^\pm Zγ$ production with leptonic decays

We present a computation of the O(alpha_s) QCD corrections to W^\pm Z γproduction at the Large Hadron Collider. The photon is considered as real, and we include full leptonic decays for the W and Z bosons. Based on the structure of the VBFNLO program package, we obtain numerical results through a fully flexible Monte Carlo program, which allows to implement general cuts and distributions of the final-state particles. The NLO QCD corrections are sizable and strongly exceed the theory error obtained by a scale variation of the leading-order result. Also, the shapes of relevant observables are significantly altered.

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arXiv2010

FeynHiggs 2.7

We present the Version 2.7 of FeynHiggs, a program for computing MSSM Higgs-boson masses and related observables, such as mixing angles, branching ratios, and couplings, including state-of-the-art higher-order contributions.

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arXiv2010

Proposals for Bottom Quark/Squark Renormalization in the Complex MSSM

We present a consistent renormalization of the top and bottom quark/squark sector of the MSSM with complex parameters (cMSSM). Various renormalization schemes are defined, analyzed analytically and tested numerically in the decays Stop_2 -> Sbot_i H+/W+ (i = 1,2). No scheme is found that produces numerically acceptable results over all the cMSSM parameter space, where problems occur mostly already for real parameters. Two schemes are identified that show the most robust behavior. A numerical analysis of the four partial stop decay widths is performed in our "preferred" scheme, "m_b, A_b DRbar". The full one-loop corrections to the corresponding partial decay widths are evaluated including hard QED and QCD radiation. We find mostly modest corrections at the one-loop level.

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arXiv2010

New Physics at the LHC. A Les Houches Report: Physics at TeV Colliders 2009 - New Physics Working Group

We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models of strong electroweak symmetry are discussed. In the fourth part, a special attention is devoted to high mass resonances, as the ones appearing in models with warped extra dimensions. Finally, prospects for models with a hidden sector/valley are presented. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 8-26 June, 2009).

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arXiv2010

SUSY-QCD corrections to MSSM Higgs boson production via gluon fusion

In the MSSM scalar h,H production is mediated by heavy quark and squark loops. The higher order QCD corrections have been obtained some time ago and turned out to be large. The full SUSY QCD corrections have been obained recently including the full mass dependence of the loop particles. We describe our calculation and present first numerical results. We also address the question of the proper treatment of the large gluino mass limit, i.e. the consistent decoupling of heavy gluino effects, and present the effective Lagrangian for decoupled gluinos.

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arXiv2008

Supersymmetric Higgs Bosons in Weak Boson Fusion

We compute the complete supersymmetric next-to-leading order corrections to the production of a light Higgs boson in weak boson fusion. The size of the electroweak corrections is of similar order as the next-to-leading order corrections in the Standard Model. The supersymmetric QCD corrections turn out to be significantly smaller than their electroweak counterparts. These higher--order corrections are an important ingredient to a precision analysis of the (supersymmetric) Higgs sector at the LHC, either as a known correction factor or as a contribution to the theory error.

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arXiv2007

The Higgs sector of the complex MSSM at two-loop order: QCD contributions

Results are presented for the leading two-loop contributions of O(alpha_t alpha_s) to the masses and mixing effects in the Higgs sector of the MSSM with complex parameters. They are obtained in the Feynman-diagrammatic approach using on-shell renormalization. The full dependence on all complex phases is taken into account. The renormalization of the appropriate contributions of the Higgs-boson sector and the scalar top and bottom sector is discussed. Our numerical analysis for the lightest MSSM Higgs-boson mass is based on the new two-loop corrections, supplemented by the full one-loop result. The corrections induced by the phase variation in the scalar top sector are enhanced by the two-loop contributions. We find that the corresponding shift in M_h1 can amount to 5 GeV.

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arXiv2007

CP-violating Loop Effects in the Higgs Sector of the MSSM

CP-violating effects in the Higgs sector of the Minimal Supersymmetric Standard Model with complex parameters (cMSSM) are induced by potentially large higher-order corrections. As a consequence, all three neutral Higgs bosons can mix with each other. Recent results for loop corrections in the Higgs sector of the cMSSM are reviewed. Results for propagator-type corrections of O(alpha_t alpha_s) and complete one-loop results for Higgs cascade decays of the kind h_a -> h_b h_c are summarised, and the proper treatment of external Higgs bosons in Higgs-boson production and decay processes is discussed.

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arXiv2007

Higgs Masses and More in the Complex MSSM with FeynHiggs

We present the latest version 2.6 of FeynHiggs, a program for computing MSSM Higgs-boson masses and related observables, such as mixing angles, branching ratios, and couplings, including state-of-the-art higher-order contributions. The most important new feature is the inclusion of the fully complex O(α_tα_s) two-loop corrections, which enables FeynHiggs to give the most precise Higgs-mass evaluation in the complex MSSM in the Feynman-diagrammatic approach to date.

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arXiv2007

Consistent Treatment of Imaginary Contributions to Higgs-Boson Masses in the MSSM

We show how the imaginary parts of the Higgs-Boson self-energies in the MSSM are consistenly taken into account in the Higgs-Boson mass determination. In a numerical example we find effects of 5 GeV in the mass difference of the two heavy neutral Higgs bosons. The imaginary contributions have been included into the code FeynHiggs.

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arXiv2007

The Higgs Boson Masses and Mixings of the Complex MSSM in the Feynman-Diagrammatic Approach

New results for the complete one-loop contributions to the masses and mixing effects in the Higgs sector are obtained for the MSSM with complex parameters using the Feynman-diagrammatic approach. The full dependence on all relevant complex phases is taken into account, and all the imaginary parts appearing in the calculation are treated in a consistent way. The renormalization is discussed in detail, and a hybrid on-shell/DRbar scheme is adopted. We also derive the wave function normalization factors needed in processes with external Higgs bosons and discuss effective couplings incorporating leading higher-order effects. The complete one-loop corrections, supplemented by the available two-loop corrections in the Feynman-diagrammatic approach for the MSSM with real parameters and a resummation of the leading (s)bottom corrections for complex parameters, are implemented into the public Fortran code FeynHiggs2.5. In our numerical analysis the full results for the Higgs-boson masses and couplings are compared with various approximations, and CP-violating effects in the mixing of the heavy Higgs bosons are analyzed in detail. We find sizable deviations in comparison with the approximations often made in the literature.

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arXiv2006

Higher-Order Corrected Higgs Bosons in FeynHiggs 2.5

Large higher-order corrections enter the Higgs boson sector of the MSSM via Higgs-boson self-energies. Their effects have to be taken into account for the correct treatment of loop-corrected Higgs-boson mass eigenstates as external (on-shell) or internal particles in Feynman diagrams. We review how the loop corrections, including momentum dependence and imaginary contributions, are correctly taken into account for external (on-shell) Higgs boson and how effective couplings can be derived. The proceedures are implemented in the code FeynHiggs 2.5.

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arXiv2006

Les Houches "Physics at TeV Colliders 2005'' Beyond the Standard Model working group: summary report

The work contained herein constitutes a report of the "Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology.

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arXiv2005

The MSSM Higgs Sector at O(alpha_b alpha_s) and Beyond

We evaluate O(alpha_b alpha_s) corrections in the MSSM Higgs boson sector, including an analysis of the renormalization in the bottom/scalar bottom sector. For mu < 0 the genuine two-loop corrections to the mass of the lightest Higgs boson mass can amount up to 3 GeV. Different renormalization schemes are applied and numerically compared. Likewise the residual dependence on the renormalization scale is investigated. This allows to determine the remaining theoretical uncertainties from unknown higher-order corrections at O(alpha_b alpha_s^2) for different regions of the MSSM parameter space.

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arXiv2005

High-Precision Predictions for the MSSM Higgs Sector at O(alpha_b alpha_s)

We evaluate O(alpha_b alpha_s) corrections in the Higgs boson sector of the CP-conserving MSSM, generalising the known result in the literature to arbitrary values of tan beta. A detailed analysis of the renormalisation in the bottom/scalar bottom sector is performed. Concerning the lightest MSSM Higgs boson mass, we find relatively small corrections for positive mu, while for mu < 0 the genuine two-loop O(alpha_b alpha_s) corrections can amount up to 3 GeV. Different renormalisation schemes are applied and numerically compared. It is demonstrated that some care has to be taken in choosing an appropriate renormalisation prescription in order to avoid artificially large corrections. The residual dependence on the renormalisation scale is investigated, and the remaining theoretical uncertainties from unknown higher-order corrections in this sector are discussed for different regions of the MSSM parameter space.

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