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Wolfgang Hollik

Publications and source records attributed to Wolfgang Hollik.

65 records · Page 4Linked to original sources
arXiv2001

Yukawa coupling quantum corrections to the self couplings of the lightest MSSM Higgs boson

A detailed analysis of the top-quark/squark quantum corrections to the lightest CP-even Higgs boson (h^0) self-couplings is presented in the MSSM. By considering the leading one-loop Yukawa-coupling contributions of O(m_t^4), we discuss the decoupling behaviour of these corrections when the top-squarks are heavy compared to the electroweak scale. As shown analytically and numerically, the large corrections can almost completely be absorbed into the h^0-boson mass. Our conclusion is that the h^0 self-couplings remain similar to the coupling of the SM Higgs boson for a heavy top-squark sector.

hep-ph↗
arXiv2001

Distinguishing Higgs models in H -> b b-bar / H -> tau^+ tau^-

We analyze the ratio of branching ratios R=BR(H->b b-bar)/BR(H->tau^+ tau^-) of Higgs boson decays as a discriminant quantity between supersymmetric and non-supersymmetric models. This ratio receives large renormalization-scheme independent radiative corrections in supersymmetric models at large \tanβ, which are absent in the Standard Model or Two-Higgs-doublet models. These corrections are insensitive to the supersymmetric mass scale. A detailed analysis in the effective Lagrangian approach shows that, with a measurement of +-21% accuracy, the Large Hadron Collider can discriminate between models if the CP-odd Higgs boson mass is below 900 GeV. An e+e- Linear Collider at 500 GeV center of mass energy can discriminate supersymmetric models up to a CP-odd Higgs mass of ~ 1.8 TeV.

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arXiv2001

The MSSM prediction for W+/- H-/+ production by gluon fusion

We discuss the associated W+/- H-/+ production in p p collision for the Large Hadron Collider. A complete one-loop calculation of the loop-induced subprocess g g -> W+/- H-/+ is presented in the framework of the Minimal Supersymmetric Standard Model (MSSM), and the possible enhancement of the hadronic cross section is investigated under the constraint from the squark direct-search results and the low-energy precision data. Because of the large destructive interplay in the quark-loop contributions between triangle-type and box-type diagrams, the squark-loop contributions turn out to be comparable with the quark-loop ones. In particular, the hadronic cross section via gluon fusion can be extensively enhanced by squark-pair threshold effects in the box-type diagrams, so that it can be as large as the hadronic cross section via the b b-bar -> W+/- H-/+ subprocess which appears at tree level.

hep-ph↗
arXiv2001

Full electroweak one-loop radiative corrections to squark decays in the MSSM

We present results on the full one-loop electroweak radiative corrections to the squark decay partial widths into charginos and neutralinos. We show the renormalization framework, and present numerical results for the third squark family. The corrections can reach values of ~ 10%, which are comparable to the radiative corrections from the strong sector of the model. Therefore they should be taken into account for the precise extraction of the SUSY parameters at future colliders.

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arXiv2000

Radiative Corrections to scalar quark decays in the MSSM

We review the one-loop corrections to the partial decay width of sbottom-quark into a top quark and a chargino for the parameter space relevant to the TESLA e+e- linear collider. We present the results available in the literature for the QCD and the Yukawa coupling corrections in a unified framework. In this way a direct comparison of the size of the various corrections is possible.

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arXiv1999

Radiative corrections to pair production of charged Higgs bosons at TESLA

Charged Higgs particles are a common feature of many extensions of the Standard Model. While its existence with masses up to the TeV scale can be probed at the Tevatron Run II and LHC hadron colliders, a precise determination of its properties would have to wait for a high energy e+e- linear collider. We have computed the complete one-loop electroweak corrections to the cross-section for charged Higgs bosons pair production in e+e- collisions, in the framework of general Two Higgs Doublet Models, as well as the Minimal Supersymmetric Standard Model. A study is presented for typical values of the model parameters, showing the general behaviour of the corrections.

hep-ph↗
arXiv1998

Top quark decay into charged Higgs boson in a general Two-Higgs-Doublet model: implications for the TEVATRON data

We analyze the unconventional top quark decay mode t -> H^+ b at the quantum level within the context of general Two-Higgs-Doublet models by including the full electroweak effects from the Yukawa couplings. The results are presented in the on-shell renormalization scheme with a physically well motivated definition of tan(beta). While the QCD corrections have been taken into account in the current experimental analyses of that decay, the electroweak effects have always been neglected. However, we find that they can be rather large and could dramatically alter the interpretation of the present data from the Tevatron collider. For instance, in large portions of the parameter space the electroweak effects prevent the Tevatron data from placing any bound at all to the charged Higgs mass for essentially any value of tan(beta).

hep-ph↗
arXiv1998

Yukawa-coupling corrections to scalar quark decays

Heavy squark decays into top and charginos or neutralinos could be an unexpected source of top quarks at hadron colliders. A detailed treatment of these processes is necessary for a reliable calculation of both the top quark production cross-section and the standard top quark branching ratio in the MSSM. Along this line we compute the electroweak corrections to the sbottom decays sbottom_a --> chargino_i top within the Yukawa coupling approximation. The calculation of these higher order contributions requires renormalization of both the bottom squark mixing angle and of tan(beta). This type of corrections gives the leading order electroweak effects at low and high tan(beta).

hep-ph↗
arXiv1997

Electroweak Radiative Corrections to Resonant Charged Gauge Boson Production

The electroweak O(alpha) contribution to the resonant single W production in a general 4-fermion process is discussed with particular emphasis on a gauge invariant decomposition into a QED-like and weak part. The cross section in the vicinity of the resonance can be represented in terms of a convolution of a `hard' Breit-Wigner-cross section, comprising the (m_t,M_H)-dependent weak 1-loop corrections, with an universal radiator function. The numerical impact of the various contributions on the W line shape are discussed, together with the concepts of s-dependent and constant width approach. Analytic formulae for the W decay width are also provided including the 1-loop electroweak and QCD corrections.

hep-ph↗
arXiv1994

Electroweak Supersymmetric Quantum Corrections to the Top Quark Width

Within the framework of the MSSM, we compute the electroweak one-loop supersymmetric quantum corrections to the width $Γ(t\rightarrow W^{+}\, b)$ of the canonical main decay of the top quark. The results are presented in two on-shell renormalization schemes parametrized either by $α$ or $G_F$. While in the standard model, and in the Higgs sector of the MSSM, the electroweak radiative corrections in the $G_F$-scheme are rather insensitive to the top quark mass and are of order of $1\%$ at most, the rest (``genuine'' part) of the supersymmetric quantum effects in the MSSM amount to a non-negligible correction that could be about one order of magnitude larger, depending on the top quark mass and of the region of the supersymmetric parameter space. These new electroweak effects, therefore, could be of the same order (and go in the same direction) as the conventional leading QCD corrections.

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