Matthias Steinhauser

Bio: Matthias Steinhauser is an academic researcher from Karlsruhe Institute of Technology. The author has contributed to research in topics: Quantum chromodynamics & Higgs boson. The author has an hindex of 77, co-authored 351 publications receiving 20037 citations. Previous affiliations of Matthias Steinhauser include Max Planck Society & University of Hamburg.

Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector

Abstract: This Report summarizes the results of the activities of the LHC Higgs Cross Section Working Group in the period 2014-2016. The main goal of the working group was to present the state-of-the-art of Higgs physics at the LHC, integrating all new results that have appeared in the last few years. The first part compiles the most up-to-date predictions of Higgs boson production cross sections and decay branching ratios, parton distribution functions, and off-shell Higgs boson production and interference effects. The second part discusses the recent progress in Higgs effective field theory predictions, followed by the third part on pseudo-observables, simplified template cross section and fiducial cross section measurements, which give the baseline framework for Higgs boson property measurements. The fourth part deals with the beyond the Standard Model predictions of various benchmark scenarios of Minimal Supersymmetric Standard Model, extended scalar sector, Next-to-Minimal Supersymmetric Standard Model and exotic Higgs boson decays. This report follows three previous working-group reports: Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables (CERN-2011-002), Handbook of LHC Higgs Cross Sections: 2. Differential Distributions (CERN-2012-002), and Handbook of LHC Higgs Cross Sections: 3. Higgs properties (CERN-2013-004). The current report serves as the baseline reference for Higgs physics in LHC Run 2 and beyond.

Estimate of B(B̄→X s γ) at O(α s 2 )

Abstract: Combining our results for various $O({\ensuremath{\alpha}}_{s}^{2})$ corrections to the weak radiative $B$-meson decay, we are able to present the first estimate of the branching ratio at the next-to-next-to-leading order in QCD. We find $\mathcal{B}(\overline{B}\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma})=(3.15\ifmmode\pm\else\textpm\fi{}0.23)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ for ${E}_{\ensuremath{\gamma}}g1.6\text{ }\text{ }\mathrm{GeV}$ in the $\overline{B}$-meson rest frame. The four types of uncertainties: nonperturbative (5%), parametric (3%), higher-order (3%), and ${m}_{c}$-interpolation ambiguity (3%) have been added in quadrature to obtain the total error.

B(s,d)→ℓ(+)ℓ(-) in the standard model with reduced theoretical uncertainty.

Abstract: We combine our new results for the O(αem) and O(αs2) corrections to Bs,d→l+l-, and present updated branching ratio predictions for these decays in the standard model. Inclusion of the new corrections removes major theoretical uncertainties of perturbative origin that have just begun to dominate over the parametric ones. For the recently observed muonic decay of the Bs meson, our calculation gives B¯(Bs→μ+μ-)=(3.65±0.23)×10-9.

Parton distributions for the LHC

Abstract: We present updated leading-order, next-to-leading order and next-to-next-to-leading order parton distribution functions (“MSTW 2008”) determined from global analysis of hard-scattering data within the standard framework of leading-twist fixed-order collinear factorisation in the $\overline{\mathrm{MS}}$ scheme. These parton distributions supersede the previously available “MRST” sets and should be used for the first LHC data taking and for the associated theoretical calculations. New data sets fitted include CCFR/NuTeV dimuon cross sections, which constrain the strange-quark and -antiquark distributions, and Tevatron Run II data on inclusive jet production, the lepton charge asymmetry from W decays and the Z rapidity distribution. Uncertainties are propagated from the experimental errors on the fitted data points using a new dynamic procedure for each eigenvector of the covariance matrix. We discuss the major changes compared to previous MRST fits, briefly compare to parton distributions obtained by other fitting groups, and give predictions for the W and Z total cross sections at the Tevatron and LHC.

Averages of b-hadron, c-hadron, and tau-lepton properties as of early 2012

Abstract: This article reports world averages of measurements of b-hadron, c-hadron, and tau-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through the end of 2011. In some cases results available in the early part of 2012 are included. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays and CKM matrix elements.