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• 1
Electronic Resource
Springer
The European physical journal 19 (2001), S. 535-546
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. We calculate the cross sections for the neutral Higgs-boson production at $e^+e^-$ colliders in the Minimal Supersymmetric Standard Model (MSSM) using the Feynman-diagrammatic approach and the on-shell renormalization scheme. We incorporate the Higgs-boson propagator corrections, evaluated up to two-loop order, into the prediction of the cross sections for the Higgs-boson production mechanism $e^+e^- \to hZ,hA$ . The propagator corrections consist of the full one-loop contribution, including the effects of non-vanishing external momentum, and at the two-loop level of the dominant corrections of ${\cal O}(\alpha\alpha_s)$ and further sub-dominant contributions. The results are supplemented with the complete set of one-loop vertex and box corrections. The effects of the two-loop propagator corrections are investigated in detail. We briefly discuss also the effect of the box contributions for high $\sqrt{s}$ . We compare our results with the case where only the corrections to the effective mixing angle, evaluated within the renormalization-group-improved one-loop Effective Potential approach, are taken into account. We find agreement better than 10% for LEP2 energies and deviations larger than 20% for $\sqrt{s} = 500$ GeV.
Type of Medium: Electronic Resource
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• 2
Electronic Resource
Springer
The European physical journal 37 (2004), S. 481-493
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. The leading corrections to electroweak precision observables in the MSSM with non-minimal flavor violation (NMFV) are calculated and the effects on M W and $\sin^2\theta_{\text{eff}}$ are analyzed. The corrections are obtained by evaluating the full one-loop contributions from the third and second generation scalar quarks, including the mixing in the scalar top and charm, as well as in the scalar bottom and strange sector. Furthermore the leading corrections to the mass of the lightest MSSM Higgs-boson, m h , is obtained. The electroweak one-loop contribution to M W can amount up to 140 MeV and up to 70 x 10-5 for $\sin^2_{\text{eff}}$ , allowing one to set limits on the NMFV parameters. The corrections for m h are not significant for moderate generation mixing.
Type of Medium: Electronic Resource
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• 3
Electronic Resource
Springer
The European physical journal 9 (1999), S. 343-366
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. We present detailed results of a diagrammatic calculation of the leading two-loop QCD corrections to the masses of the neutral ${\cal CP}$ -even Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM). The two-loop corrections are incorporated into the full diagrammatic one-loop result and supplemented with refinement terms that take into account leading electroweak two-loop and higher-order QCD contributions. The dependence of the results for the Higgs-boson masses on the various MSSM parameters is analyzed in detail, with a particular focus on the part of the parameter space accessible at LEP2 and the upgraded Tevatron. For the mass of the lightest Higgs boson, $m_h$ , a parameter scan has been performed, yielding an upper limit on $m_h$ which depends only on $\tan \beta$ . The results for the Higgs-boson masses are compared with results obtained by renormalization group methods. Good agreement is found in the case of vanishing mixing in the scalar quark sector, while sizable deviations occur if squark mixing is taken into account.
Type of Medium: Electronic Resource
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• 4
Electronic Resource
Springer
The European physical journal 16 (2000), S. 139-153
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. In the Minimal Supersymmetric Standard Model (MSSM) we incorporate the Higgs-boson propagator corrections, evaluated up to two-loop order, into the prediction of $\Gamma(h \to f\bar f)$ and $BR(h \to f \bar f)$ for $f = b, c, \tau$ . The propagator corrections consist of the full one-loop contribution, including the effects of non-vanishing external momentum, and corrections of $\mathcal{O}(\alpha\alpha_s)$ at the two-loop level. The results are supplemented with the dominant one-loop QED corrections and final state QCD corrections from both gluons and gluinos. The effects of the two-loop propagator corrections and of the one-loop gluino contributions are investigated in detail. Our results are compared with the result obtained within the renormalization group approach. Agreement within 10% is found for most parts of the MSSM parameter space.
Type of Medium: Electronic Resource
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• 5
Electronic Resource
Springer
The European physical journal 25 (2002), S. 113-123
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. The ”Snowmass Points and Slopes” (SPS) are a set of benchmark points and parameter lines in the MSSM parameter space corresponding to different scenarios in the search for Supersymmetry at present and future experiments. This set of benchmarks was agreed upon at the 2001 ”Snowmass Workshop on the Future of Particle Physics” as a consensus based on different existing proposals.
Type of Medium: Electronic Resource
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• 6
Electronic Resource
Springer
The European physical journal 39 (2005), S. 465-481
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. We evaluate $\mathcal{O}{\alpha_b \alpha_s}$ corrections in the Higgs boson sector of the $\mathcal{C}P$ -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 μ, while for $\mu 〈 0$ the genuine two-loop $\mathcal{O}{\alpha_b \alpha_s}$ 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.
Type of Medium: Electronic Resource
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• 7
Electronic Resource
Springer
The European physical journal 28 (2003), S. 133-143
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. The status of the evaluation of the MSSM Higgs sector is reviewed. The phenomenological impact of recently obtained corrections is discussed. In particular it is shown that the upper bound on mh within the MSSM is shifted upwards. Consequently, lower limits on $\tan\beta$ obtained by confronting the upper bound as function of $\tan\beta$ with the lower bound on mh from Higgs searches are significantly weakened. Furthermore, th e region in the MA- $\tan\beta$ -plane where the coupling of the lightest Higgs boson to down-type fermions is suppressed is modified. The presently not calculated higher-order corrections to the Higgs-boson mass matrix are estimated to shift the mass of the lightest Higgs boson by up to 3 GeV.
Type of Medium: Electronic Resource
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• 8
Electronic Resource
Springer
The European physical journal 28 (2003), S. 27-44
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. We present the machine parameters and physics capabilities of the CLIC Higgs Experiment (CLICHE), a low-energy $\gamma \gamma$ collider based on CLIC 1, the demonstration project for the higher-energy two-beam accelerator CLIC. CLICHE is conceived as a factory capable of producing around 20,000 light Higgs bosons per year. We discuss the requirements for the CLIC 1 beams and a laser backscattering system capable of producing a $\gamma \gamma$ total (peak) luminosity of $2.0 (0.36) \times 10^{34}$ cm-2s-1 with $E_{CM}(\gamma \gamma) \sim 115$ GeV. We show how CLICHE could be used to measure accurately the mass, $\bar b b$ , WW and $\gamma \gamma$ decays of a light Higgs boson. We illustrate how these measurements may distinguish between the Standard Model Higgs boson and those in supersymmetric and more general two-Higgs-doublet models, complement ing the measurements to be made with other accelerators. We also comment on other prospects in $\gamma \gamma$ and $e^- \gamma$ physics with CLICHE.
Type of Medium: Electronic Resource
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• 9
Electronic Resource
Springer
The European physical journal 22 (2001), S. 521-534
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. In the Minimal Supersymmetric Standard Model with complex parameters (cMSSM) we calculate higher order corrections to the Higgs boson sector in the Feynman-diagrammatic approach using the on-shell renormalization scheme. The application of this approach to the cMSSM, being complementary to existing approaches, is analyzed in detail. Numerical examples for the leading fermionic corrections, including the leading two-loop effects, are presented. Numerical agreement within 10% with other approaches is found for small and moderate mixing in the scalar top sector. The leading fermionic corrections, supplemented by the full logarithmic one-loop and the leading two-loop contributions are implemented into the public Fortran code FeynHiggsFastC.
Type of Medium: Electronic Resource
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• 10
Electronic Resource
Springer
The European physical journal 26 (2003), S. 601-607
ISSN: 1434-6052
Source: Springer Online Journal Archives 1860-2000
Topics: Physics
Notes: Abstract. The Higgs boson search has shifted from LEP2 to the Tevatron and will subsequently move to the LHC. Due to the different initial states, the Higgs production and decay channels relevant for Higgs boson searches are different at hadron colliders compared to LEP2. We suggest new benchmark scenarios for the MSSM Higgs boson search at hadron colliders that exemplify the phenomenology of different parts of the MSSM parameter space. Besides the $\m_h^{\rm max}$ scenario and the no-mixing scenario used in the LEP2 Higgs boson searches, we propose two new scenarios. In one scenario the main production channel at the LHC, $gg \to h$ , is suppressed over a wide part of the MA- $\tan \beta$ -plane. In the other scenario, important Higgs decay channels at the Tevatron and at the LHC, $h \to b \bar b$ and $h \to \tau^+ \tau^-$ , can be suppressed. All scenarios fulfill the LEP2 constraints for nearly the whole MA- $\tan \beta$ -plane.
Type of Medium: Electronic Resource
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