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G. Weiglein

Publications and source records attributed to G. Weiglein.

At least 55 records · Page 3Linked to original sources

Exclusive production of the BSM Higgs bosons at the LHC

We review the prospects for Central Exclusive Production (CEP) of BSM Higgs bosons at the LHC using forward proton detectors proposed to be installed at 220 m and 420 m from the ATLAS and/ or CMS. Results are presented for MSSM in standard benchmark scenarios, in scenarios compatible with the Cold Dark Matter relic abundance and other precision measurements, and for SM with a fourth generation of fermions. We show that CEP can give a valuable information about spin-parity properties of the Higgs bosons.

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Supersymmetry and Dark Matter in Light of LHC 2010 and Xenon100 Data

We make frequentist analyses of the CMSSM, NUHM1, VCMSSM and mSUGRA parameter spaces taking into account all the public results of searches for supersymmetry using data from the 2010 LHC run and the Xenon100 direct search for dark matter scattering. The LHC data set includes ATLAS and CMS searches for jets + ETslash events (with or without leptons) and for the heavier MSSM Higgs bosons, and the upper limit on bs to mu mu including data from LHCb as well as CDF and D0. The absences of signals in the LHC data favour somewhat heavier mass spectra than in our previous analyses of the CMSSM, NUHM1 and VCMSSM, and somewhat smaller dark matter scattering cross sections, all close to or within the pre-LHC 68% CL ranges, but do not impact significantly the favoured regions of the mSUGRA parameter space. We also discuss the impact of the Xenon100 constraint on spin-independent dark matter scattering, stressing the importance of taking into account the uncertainty in the pi-nucleon sigma term, that affects the spin-independent scattering matrix element, and we make predictions for spin-dependent dark matter scattering. Finally, we discuss briefly the potential impact of the updated predictions for sparticle masses in the CMSSM, NUHM1, VCMSSM and mSUGRA on future e+ e- colliders.

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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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BSM Higgs Physics in the Exclusive Forward Proton Mode at the LHC

We investigate the prospects for Central Exclusive Diffractive (CED) production of BSM Higgs bosons at the LHC using forward proton detectors installed at 220 m and 420 m distance around ATLAS and / or CMS. We update a previous analysis for the MSSM taking into account improvements in the theoretical calculations and the most recent exclusion bounds from the Tevatron. We extend the MSSM analysis to new benchmark scenarios that are in agreement with the cold dark matter relic abundance and other precision measurements. We analyse the exclusive production of Higgs bosons in a model with a fourth generation of fermions. Finally, we comment on the determination of Higgs spin-parity and coupling structures at the LHC and show that the forward proton mode could provide crucial information on the CP properties of the Higgs bosons.

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Frequentist Analysis of the Parameter Space of Minimal Supergravity

We make a frequentist analysis of the parameter space of minimal supergravity (mSUGRA), in which, as well as the gaugino and scalar soft supersymmetry-breaking parameters being universal, there is a specific relation between the trilinear, bilinear and scalar supersymmetry-breaking parameters, A_0 = B_0 + m_0, and the gravitino mass is fixed by m_{3/2} = m_0. We also consider a more general model, in which the gravitino mass constraint is relaxed (the VCMSSM). We combine in the global likelihood function the experimental constraints from low-energy electroweak precision data, the anomalous magnetic moment of the muon, the lightest Higgs boson mass M_h, B physics and the astrophysical cold dark matter density, assuming that the lightest supersymmetric particle (LSP) is a neutralino. In the VCMSSM, we find a preference for values of m_{1/2} and m_0 similar to those found previously in frequentist analyses of the constrained MSSM (CMSSM) and a model with common non-universal Higgs masses (NUHM1). On the other hand, in mSUGRA we find two preferred regions: one with larger values of both m_{1/2} and m_0 than in the VCMSSM, and one with large m_0 but small m_{1/2}. We compare the probabilities of the frequentist fits in mSUGRA, the VCMSSM, the CMSSM and the NUHM1: the probability that mSUGRA is consistent with the present data is significantly less than in the other models. We also discuss the mSUGRA and VCMSSM predictions for sparticle masses and other observables, identifying potential signatures at the LHC and elsewhere.

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Implications of Initial LHC Searches for Supersymmetry

The CMS and ATLAS Collaborations have recently published the results of initial direct LHC searches for supersymmetry analyzing ~ 35/pb of data taken at 7 TeV in the centre of mass. We incorporate these results into a frequentist analysis of the probable ranges of parameters of simple versions of the minimal supersymmetric extension of the Standard Model (MSSM), namely the constrained MSSM (CMSSM), a model with common non-universal Higgs masses (NUHM1), the very constrained MSSM (VCMSSM) and minimal supergravity (mSUGRA). We present updated predictions for the gluino mass, m_gl, the light Higgs boson mass, M_h, BR(B_s to mu mu) and the spin-independent dark matter scattering cross section, sigma_SI. The CMS and ATLAS data make inroads into the CMSSM, NUHM1 and VCMSSM (but not mSUGRA) parameter spaces, thereby strengthening previous lower limits on sparticle masses and upper limits on sigma_SI in the CMSSM and VCMSSM. The favoured ranges of BR(B_s to mu mu) in the CMSSM, VCMSSM and mSUGRA are close to the Standard Model, but considerably larger values of BR(B_s to mu mu) are possible in the NUHM1. Applying the CMS and ATLAS constraints improves the consistency of the model predictions for M_h with the LEP exclusion limits.

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BSM Higgs Physics at the LHC in the Forward Proton Mode

We review the prospects for Central Exclusive Diffractive (CED) production of Higgs bosons in the SM with a fourth generation of fermions at the LHC using forward proton detectors installed at 220m and 420m distance around ATLAS and / or CMS. We discuss the determination of Higgs spin-parity and coupling structures at the LHC and show that the forward proton mode would provide a critical information on the CP properties of the Higgs bosons.

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Top, GigaZ, MegaW

We review the physics potential of top mass measurements and the GigaZ/MegaW options of the International Linear Collider (ILC) for probing New Physics models and especially the Minimal Supersymmetric Standard Model (MSSM). We demonstrate that the anticipated experimental accuracies at the ILC for the top-quark mass, m_t, the W boson mass, M_W, and the effective leptonic weak mixing angle, sin^2 theta_eff, will provide a high sensitivity to quantum effects of New Physics. In particular, a new and more precise measurement of sin^2 theta_eff, for which the experimental central value is currently obtained from an average where the most precise single measurements differ by more than three standard deviations, could lead to a situation where both the Standard Model and the MSSM in its most general form are ruled out. Alternatively, the precision measurements may resolve virtual effects of SUSY particles even in scenarios where the SUSY particles are so heavy that they escape direct detection at the LHC and the first phase of the ILC.

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Predicting Supersymmetry

We review the result of SUSY parameter fits based on frequentist analyses of experimental constraints from electroweak precision data, (g-2)_mu, B-physics and cosmological data. We investigate the parameters of the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking mass parameters, and a model with common non-universal Higgs mass parameters in the superpotential (NUHM1). Shown are the results for the SUSY and Higgs spectrum of the models. Many sparticle masses are highly correlated in both the CMSSM and NUHM1, and parts of the regions preferred at the 68% C.L. are accessible to early LHC running. The best-fit points could be tested even with 1/fb at sqrt[s] = 7 Tev.

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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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The Hunt for New Physics at the Large Hadron Collider

The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Additionally, the LHC will be a top factory and accurate measurements of the properties of the top and its rare decays will provide a window to new physics. Further, the LHC could shed light on the origin of neutralino masses if the new physics associated with their generation lies in the TeV region. Finally, the LHC is also a laboratory to test the hypothesis of TeV scale strings and D-brane models. An overview of these possibilities is presented in the spirit that it will serve as a companion to the Technical Design Reports (TDRs) by the particle detector groups ATLAS and CMS to facilitate the test of the new theoretical ideas at the LHC. Which of these ideas stands the test of the LHC data will govern the course of particle physics in the subsequent decades.

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Predictions for m_t and m_W in Minimal Supersymmetric Models

Using a frequentist analysis of experimental constraints within two versions of the minimal supersymmetric extension of the Standard Model, we derive the predictions for the top quark mass, m_t, and the W boson mass, m_W. We find that the supersymmetric predictions for both m_t and m_W, obtained by incorporating all the relevant experimental information and state-of-the-art theoretical predictions, are highly compatible with the experimental values with small remaining uncertainties, yielding an improvement compared to the case of the Standard Model.

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SUSY Les Houches Accord 2

The Supersymmetry Les Houches Accord (SLHA) provides a universal set of conventions for conveying spectral and decay information for supersymmetry analysis problems in high energy physics. Here, we propose extensions of the conventions of the first SLHA to include various generalisations: the minimal supersymmetric standard model with violation of CP, R-parity, and flavour, as well as the simplest next-to-minimal model.

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SUSY Les Houches Accord: Interfacing SUSY Spectrum Calculators, Decay Packages, and Event Generators

An accord specifying a unique set of conventions for supersymmetric extensions of the Standard Model together with generic file structures for 1) supersymmetric model specifications and input parameters, 2) electroweak scale supersymmetric mass and coupling spectra, and 3) decay tables is defined, to provide a universal interface between spectrum calculation programs, decay packages, and high energy physics event generators.

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Precise Predictions for Higgs Production in Neutralino Decays in the Complex MSSM

Complete one-loop results are obtained for the class of processes chi^0_i->chi^0_j h_a in the MSSM where all parameters entering this process beyond lowest order are allowed to have arbitrary CP-violating phases. An on-shell renormalisation scheme is worked out for the chargino-neutralino sector that properly takes account of imaginary parts arising from complex parameters and from absorptive parts of loop integrals. The genuine vertex contributions to the neutralino decay amplitudes are combined with two-loop propagator-type corrections for the outgoing Higgs boson. In this way the currently most precise prediction for this class of processes is obtained. The numerical impact of the genuine vertex corrections is studied for several examples of CP-conserving and CP-violating scenarios. We find that significant effects on the decay widths and branching ratios are possible even in the CP-conserving MSSM. In the CP-violating CPX benchmark scenario the corrections to the decay width are found to be particularly large, namely, of order 45% for a Higgs mass of 40 GeV. This parameter region of the CPX scenario where a very light Higgs boson is unexcluded by present data is analysed in detail. We find that in this parameter region, which will be difficult to cover by standard Higgs search channels at the LHC, the branching ratio for the decay chi^0_2->chi^0_1 h_1 is large. This may offer good prospects to detect such a light Higgs boson in cascade decays of supersymmetric particles.

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BSM Higgs Studies at the LHC in the Forward Proton Mode

The prospects for central exclusive diffractive (CED) production of BSM Higgs bosons at the LHC are reviewed. This comprises the production of MSSM and 4th generation Higgs bosons. The sensitivity of the searches in the forward proton mode for the Higgs bosons as well as the possibility of a coupling structure determination are briefly discussed.

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New HiggsBounds from LEP and the Tevatron

We review the program HiggsBounds that tests theoretical predictions of models with arbitrary Higgs sectors against the exclusion bounds obtained from the Higgs searches at LEP and the Tevatron. We explicitly list the bounds that have been added after the first release of HiggsBounds.

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From the LHC to Future Colliders

Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300/fb of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10/fb of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions.

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