ABSTRACT
High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the Z ( ν ν ¯ ) + jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by Z ( â + â - ) + jet, W ( â ν ) + jet and γ + jet production, and extrapolating to the Z ( ν ν ¯ ) + jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the-art calculations for all relevant V + jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different V + jet processes play a key role. The anticipated theoretical uncertainty in the Z ( ν ν ¯ ) + jet background is at the few percent level up to the TeV range.
ABSTRACT
The first complete calculation of the next-to-leading-order electroweak corrections to four-lepton production at the LHC is presented, where all off-shell effects of intermediate Z bosons and photons are taken into account. Focusing on the mixed final state µ^{+}µ^{-}e^{+}e^{-}, we study differential cross sections that are particularly interesting for Higgs boson analyses. The electroweak corrections are divided into photonic and purely weak corrections. The former exhibit patterns familiar from similar W- or Z-boson production processes with very large radiative tails near resonances and kinematical shoulders. The weak corrections are of the generic size of 5% and show interesting variations, in particular, a sign change between the regions of resonant Z-pair production and the Higgs signal.
ABSTRACT
A comprehensive review of physics at an [Formula: see text] linear collider in the energy range of [Formula: see text] GeV-3 TeV is presented in view of recent and expected LHC results, experiments from low-energy as well as astroparticle physics. The report focusses in particular on Higgs-boson, top-quark and electroweak precision physics, but also discusses several models of beyond the standard model physics such as supersymmetry, little Higgs models and extra gauge bosons. The connection to cosmology has been analysed as well.
ABSTRACT
Top-antitop quark pairs belong to the most abundantly produced and precisely measurable heavy-particle signatures at hadron colliders and allow for crucial tests of the standard model and new physics searches. Here we report on the calculation of the next-to-leading order (NLO) QCD corrections to hadronic W(+)W(-)bb production, which provides a complete NLO description of the production of top-antitop pairs and their subsequent decay into W bosons and bottom quarks, including interferences, off-shell effects, and nonresonant backgrounds. Numerical predictions for the Tevatron and the LHC are presented.
ABSTRACT
We report on the calculation of the full next-to-leading-order QCD corrections to the production of ttbb final states at the LHC, which deliver a serious background contribution to the production of a Higgs boson (decaying into a bb pair) in association with a tt pair. While the corrections significantly reduce the unphysical scale dependence of the leading-order cross section, our results predict an enhancement of the ttbb production cross section by a K factor of about 1.8.
ABSTRACT
We report on the calculation of the next-to-leading-order QCD corrections to the production of W-boson pairs in association with a hard jet at the Fermilab Tevatron and CERN Large Hadron Collider, which is an important source of background for Higgs boson and new-physics searches. The corrections stabilize the leading-order prediction for the cross section considerably, in particular, if a veto against the emission of a second hard jet is applied.
ABSTRACT
Radiative corrections of strong and electroweak interactions are presented at next-to-leading order for the production of a Higgs boson plus two hard jets via weak interactions at the CERN Large Hadron Collider. The calculation includes all weak-boson fusion and quark-antiquark annihilation diagrams as well as the corresponding interferences. The electroweak corrections, which are discussed here for the first time, reduce the cross sections by 5% and thus are of the same order of magnitude as the QCD corrections.
ABSTRACT
We report on the calculation of the next-to-leading-order QCD corrections to the production of top-quark-top-antiquark pairs in association with a hard jet at the Fermilab Tevatron and the CERN Large Hadron Collider. We present results for the tt[over ]+jet cross section and the forward-backward charge asymmetry. The corrections stabilize the leading-order prediction for the cross section. The charge asymmetry receives large corrections.
ABSTRACT
Higgs bosons can be searched for in the channels pp macro/pp-->tt macro H + X at the Fermilab Tevatron and the Cern Large Hadron Collider (LHC). We have calculated the QCD corrections to these processes in the standard model at next-to-leading order. The higher-order corrections reduce the renormalization and factorization scale dependence considerably and stabilize the theoretical predictions for the cross sections. At the central scale mu = (2m(t)+M(H))/2 the properly defined K factors are slightly below unity for the Tevatron (K approximately 0.8) and slightly above unity for the LHC (K approximately 1.2).
