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Wolfgang Hollik

Publications and source records attributed to Wolfgang Hollik.

At least 55 records · Page 3Linked to original sources
arXiv2006

Towards a Realistic MSSM Prediction for Neutrino-nucleon Deep-inelastic Scattering

We discuss the radiative corrections to charged and neutral current deep-inelastic neutrino--nucleon scattering in the minimal supersymmetric standard model (MSSM). In particular, we study deviations, delta_R^nu(nu-bar), from the Standard Model prediction for the ratios of neutral- to charged-current cross sections, taking into account all sources for deviations in the MSSM, i.e. different contributions from virtual Higgs bosons and virtual superpartners. Our calculation includes the full q^2 dependence of the one-loop amplitudes, parton distribution functions and a NuTeV-inspired process kinematics. We present results of a scan of delta_R^nu(nu-bar) over the relevant MSSM parameter space.

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arXiv2006

Higgs-Boson Production in Association with Heavy Quarks

Associated production of a Higgs boson with a heavy, i.e. top or bottom, quark-anti-quark pair provide observation channels for Higgs bosons at the LHC which can be used to measure the respective Yukawa couplings. For the light supersymmetric Higgs boson we present SUSY-QCD corrections at the one-loop level, which constitute a significant contribution to the cross section.

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arXiv2006

One-loop calculations of the decay of the next-to-lightest neutralino in the MSSM

We calculate one-loop corrections to the decays of the next-to-lightest neutralino $\tildeχ_2^0$ into the lightest neutralino $\tildeχ_1^0$ and two leptons; this includes diagrams where a real photon is emitted. In cases where two-body decays $\tildeχ_2^0 \to \tilde{l}^\pm_1 l^\mp \to \tildeχ_1^0 l^- l^+$ are kinematically allowed, we calculate these decays both with and without the single-pole approximation, and find consistent results. For example, for the minimal supergravity parameter set SPS1a, the integrated partial widths (the branching ratios) for $\tildeχ_2^0\to \tildeχ_1^0 l^- l^+ (l = e, μ)$ are enhanced by about 15.5 (13.6) percent by the one-loop corrections. We also study a scenario where $\tilde χ_2^0$ cannot undergo two-body decays, and find corrections to these branching ratios of about 13.6 percent. Moreover, we study the dilepton invariant mass ($M_{l^+ l^-}$) distribution, whose endpoint is often used in analyses that aim to reconstruct (differences of) supersymmetric particle masses at the LHC. The shape of this distribution is altered significantly by the emission of hard photons. For example, for the SPS1a parameter set the peak of the $M_{l^+ l^-}$ distribution is shifted by several GeV when these contributions are included.

hep-ph↗
arXiv2006

Single top-quark production by direct supersymmetric flavor-changing neutral-current interactions at the LHC

Production of (electrically neutral) heavy-quark pairs, such as t{\bar c} and {\bar t}c, is extremely suppressed in the SM. In supersymmetric (SUSY) theories, such as the MSSM, the number of these events can be significantly enhanced thanks (mainly) to the FCNC couplings of gluinos. We compute the efficiency of this mechanism for FCNC production of heavy quarks at the LHC. We find that σ(pp\to t\bar{c}+\bar{t}c) can reach 1 pb, and therefore one can expect up to 10^{5} events per 100 fb^{-1} of integrated luminosity (with no counterpart in the SM). Their detection would be instant evidence of new physics, and could be a strong indication of underlying SUSY dynamics.

hep-ph↗
arXiv2005

MSSM Higgs-boson mass predictions and two-loop non-supersymmetric counterterms

The evaluation of Yukawa-enhanced two-loop contributions to the MSSM Higgs-boson mass is considered. We prove the common assumption that regularization by dimensional reduction preserves supersymmetry at the required level. Thus generating counterterms by multiplicative renormalization is correct. Technically, we identify a suitable Slavnov-Taylor identity, use a recently developed method to evaluate it at the two-loop level, and show that it is valid in dimensional reduction.

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arXiv2004

Production of Neutral Higgs + Jet at the LHC in the SM and the MSSM

The cross section prediction for the production of the lightest neutral Higgs boson in association with a high-p_T hadronic jet is presented in the framework of the minimal supersymmetric standard model (MSSM) and compared to the SM case. Prospects for the CERN Large Hadron Collider (LHC) are discussed.

hep-ph↗
arXiv2003

Radiative corrections to scalar-fermion pair production in high energy e+e- collisions

We study the one-loop radiative corrections to pair production of the supersymmetric scalar partners of the standard fermions in e+e- annihilation. Both electroweak and SUSY-QCD corrections are considered. Applications are for production of scalar fermions of the third generation, $e^+e^-\to \wt{f}_i \wt{f}_j^*$ (i,j=1,2), $f=t, b,τ$, as well as for production of scalar quarks of the first and second generation. Effects on integrated cross sections are discussed and also the one-loop induced forward-backward asymmetries are studied. It is found that at low energy, \sqrt{s}\approx 500 \to 1000 GeV, the corrections are dominated by the QCD contributions, At high energy, $\sqrt{s}\geq 2$ TeV, the electroweak box diagrams give a substantial contribution and even dominate in some regions of parameters space. The purely loop-induced forward-backward asymmetry can reach values of several per cent.

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arXiv2003

Electroweak radiative corrections to sfermion decays

We analyze the partial decay widths of sfermions decaying into charginos and neutralinos $Γ(\tilde{f} -> f'χ)$ at the one-loop level, including the electroweak and strong corrections. We present the renormalization framework, and discuss the value of the corrections. Since these corrections show non-decoupling effects, we analyze the radiative effects induced by a heavy squark sector into the lepton-slepton-chargino/neutralino couplings. We conclude that some knowledge of the heavy sector is needed in order to provide a sufficiently precise prediction for slepton observables at an $e^+e^-$ Linear Collider.

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arXiv2003

Some results on the distinction of Higgs boson models

We present results on the analysis of the ratio of branching ratios $R=BR(H->b\bar{b})/BR(H->τ^+τ^-)$ of Higgs boson decays as a discriminant quantity between supersymmetric and non-supersymmetric models. A detailed analysis in the effective Lagrangian approach shows how one could discriminate between models at the Large Hadron Collider and the $e^+e^-$ Linear Collider at 500 GeV center of mass energy.

hep-ph↗
arXiv2003

MSSM Higgs bosons associated with high-pT jets at hadron colliders

The cross section for the production of the lightest neutral Higgs boson in association with a high-pT hadronic jet, calculated in the framework of the minimal supersymmetric standard model (MSSM), is presented. The expectations for the hadronic cross section at the Large Hadron Collider are discussed using reasonable kinematical cuts. In particular the contributions from superpartner loops to the cross section and their dependence on the parameters of the MSSM are investigated and found to be significant. Comparisons show that the production rate for h0 + jet in the MSSM can differ widely from the corresponding standard-model prediction.

hep-ph↗
arXiv2003

Decoupling behaviour of O(m_t^4) corrections to the h^0 self-couplings

The decoupling behaviour of the leading one-loop Yukawa-coupling contributions of O(m_t^4) to the lightest MSSM Higgs boson self-couplings, when the top-squarks are heavy as compared to the electroweak scale, are discussed. As shown analytically and numerically, the large corrections can almost completely be absorbed into the h^0-boson mass and therefore, the h^0 self-couplings remain similar to the coupling of the SM Higgs boson for a heavy top-squark sector.

hep-ph↗
arXiv2002

Fermionic decays of sfermions: a complete discussion at one-loop order

We present a definition of an on-shell renormalization scheme for the sfermion and chargino-neutralino sector of the Minimal Supersymmetric Standard Model (MSSM). Then, apply this renormalization framework to the interaction between charginos/neutralinos and sfermions. A kind of universal corrections is identified, which allow to define effective chargino/neutralino coupling matrices. In turn, these interactions generate (universal) non-decoupling terms that grow as the logarithm of the heavy mass. Therefore the full MSSM spectrum must be taken into account in the computation of radiative corrections to observables involving these interactions. As an application we analyze the full one-loop electroweak radiative corrections to the partial decay widths Γ(\tilde{f} -> f\neut) and Γ(\tilde{f} -> f'\cplus) for all sfermion flavours and generations. These are combined with the QCD corrections to compute the corrected branching ratios of sfermions. It turns out that the electroweak corrections can have an important impact on the partial decay widths, as well as the branching ratios, in wide regions of the parameter space. The precise value of the corrections is strongly dependent on the correlation between the different particle masses.

hep-ph↗
arXiv2002

Self-interactions of the lightest MSSM Higgs boson in the large pseudoscalar-mass limit

We investigate the decoupling properties of the Higgs-sector-induced one-loop corrections in the lightest Higgs-boson self-couplings, in the framework of the Minimal Supersymmetric Standard Model (MSSM). The renormalized n-point vertex functions with external Higgs particles in the MSSM and in the SM are derived to the one-loop level and compared in the MA >> MZ limit. The computation has been done in a general R_{xi} gauge and the on-shell renormalization scheme is chosen. By a comparison of the renormalized lightest Higgs-boson h^0 vertex functions with respect to the corresponding SM ones, we find that the differences between the predictions of both models are summarized in the lightest Higgs-boson mass correction Delta Mh. Consequently, the radiative corrections are absorbed in the Higgs-boson mass, and the trilinear and quartic h^0 self-couplings acquire the same structure as the couplings of the SM Higgs-boson. Therefore, decoupling of the heavy MSSM Higgs bosons occurs and the MSSM h^0 self-interactions converge to the SM ones in the MA >> MZ limit.

hep-ph↗
arXiv2002

Renormalization of the Minimal Supersymmetric Standard Model

The renormalization of the Minimal Supersymmetric Standard Model (MSSM) is presented. We describe symmetry identities that constitute a framework in which the MSSM is completely characterized and renormalizability can be proven. Furthermore, we discuss applications of this framework for the determination of symmetry-restoring counterterms, the gauge dependence of tan(beta) and the derivation of non-renormalization theorems.

hep-ph↗
arXiv2002

Full one-loop corrections to sfermion decays

We analyze the partial decay widths of sfermions decaying into charginos and neutralinos Γ(\sfermion -> f'χ) at the one-loop level. We present the renormalization framework, and discuss the value of the corrections for top- and bottom-squark decays.

hep-ph↗
arXiv2002

Renormalization of the Minimal Supersymmetric Standard Model

The renormalization of the Minimal Supersymmetric Standard Model of electroweak interactions is presented to all orders of perturbation theory using the algebraic method. Special attention is directed to the issues of soft supersymmetry breaking, gauge fixing, and infrared finiteness. We discuss the implications of $\hbar$-dependent field parametrizations on the counterterm structure and provide a complete set of on-shell normalization conditions.

hep-ph↗
arXiv2002

$O(α_s)$ Corrections to $b \bar b \to W^{\pm}H^{\mp}$ at the CERN Large Hadron Collider

The $O(α_{s})$ corrections to the cross section for $b \bar b \to W^{\pm}H^{\mp}$ at the LHC are calculated in the minimal supersymmetric standard model (MSSM) in the $\bar{MS}$ and OS (on-mass-shell) renormalization schemes. The results in two schemes are in good agreement. In the $\bar{MS}$ scheme, the QCD corrections are negative and within $ -14% \sim -20%$ for charged Higgs mass up to 1 TeV and $\tanβ>15$. For $\tanβ=2$, the magnitude of the QCD corrections can be greater than 30%.

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