10 research outputs found
Radiative corrections to W-boson hadroproduction: higher-order electroweak and supersymmetric effects
The high accuracy envisaged for future measurements of W-boson production at
hadron colliders has to be matched by precise theoretical predictions. We study
the impact of electroweak radiative corrections on W-boson production cross
sections and differential distributions at the Tevatron and at the LHC. In
particular, we include photon-induced processes, which contribute at O(alpha),
and leading radiative corrections beyond O(alpha) in the high-energy Sudakov
regime and from multi-photon final-state radiation. We furthermore present the
calculation of the complete supersymmetric next-to-leading-order electroweak
and QCD corrections to W-boson hadroproduction within the MSSM. The
supersymmetric corrections turn out to be negligible in the vicinity of the W
resonance in general, reaching the percent level only at high lepton transverse
momentum and for specific choices of the supersymmetric parameters.Comment: 30 pages, 10 figures, 2 new sections, including a comparison with
previous results on multi-photon radiation; version published in PR
Soft-gluon resummation for squark and gluino hadroproduction
We consider the resummation of soft gluon emission for squark and gluino
hadroproduction at next-to-leading-logarithmic (NLL) accuracy in the framework
of the minimal supersymmetric standard model. We present analytical results for
squark-squark and squark-gluino production and provide numerical predictions
for all squark and gluino pair-production processes at the Tevatron and at the
LHC. The size of the soft-gluon corrections and the reduction in the scale
uncertainty are most significant for processes involving gluino production. At
the LHC, where the sensitivity to squark and gluino masses ranges up to 3 TeV,
the corrections due to NLL resummation over and above the NLO predictions can
be as high as 35% in the case of gluino-pair production, whereas at the
Tevatron, the NLL corrections are close to 40% for squark-gluino final states
with sparticle masses around 500 GeV.Comment: 31 pages, 7 figure
Supersymmetric top and bottom squark production at hadron colliders
The scalar partners of top and bottom quarks are expected to be the lightest
squarks in supersymmetric theories, with potentially large cross sections at
hadron colliders. We present predictions for the production of top and bottom
squarks at the Tevatron and the LHC, including next-to-leading order
corrections in supersymmetric QCD and the resummation of soft gluon emission at
next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order
corrections on total cross sections and transverse-momentum distributions, and
provide an estimate of the theoretical uncertainty due to scale variation and
the parton distribution functions.Comment: 29 pages, 6 figure
Resummation for supersymmetric particle production at hadron colliders
The search for supersymmetry is among the most important tasks at current and future colliders. Especially the production of coloured supersymmetric particles would occur copiously in hadronic collisions. Since these production processes are of high relevance for experimental searches accurate theoretical predictions are needed. Higher-order corrections in quantum chromodynamics (QCD) to these processes are dominated by large logarithmic terms due to the emission of soft gluons from initial-state and final-state particles. A systematic treatment of these logarithms to all orders in perturbation theory is provided by resummation methods. We perform the resummation of soft gluons at next-to-leading-logarithmic (NLL) accuracy for all possible production processes in the framework of the Minimal Supersymmetric Standard Model. In particular we consider pair production processes of mass-degenerate light-flavour squarks and gluinos as well as the pair production of top squarks and non-mass-degenerate bottom squarks. We present analytical results for all considered processes including the soft anomalous dimensions. Moreover numerical predictions for total cross sections and transverse-momentum distributions for both the Large Hadron Collider (LHC) and the Tevatron are presented. We provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions. The inclusion of NLL corrections leads to a considerable reduction of the theoretical uncertainty due to scale variation and to an enhancement of the next-to-leading order (NLO) cross section predictions. The size of the soft-gluon corrections and the reduction in the scale uncertainty are most significant for processes involving gluino production. At the LHC, where the sensitivity to squark and gluino masses ranges up to 3 TeV, the corrections due to NLL resummation over and above the NLO predictions can be as high as 35 % in the case of gluino-pair production, whereas at the Tevatron, the NLL corrections are close to 40 % for squark-gluino final states with supersymmetric particle masses around 500 GeV
Resummation for supersymmetric particle production at hadron colliders
The search for supersymmetry is among the most important tasks at current and future colliders. Especially the production of coloured supersymmetric particles would occur copiously in hadronic collisions. Since these production processes are of high relevance for experimental searches accurate theoretical predictions are needed. Higher-order corrections in quantum chromodynamics (QCD) to these processes are dominated by large logarithmic terms due to the emission of soft gluons from initial-state and final-state particles. A systematic treatment of these logarithms to all orders in perturbation theory is provided by resummation methods. We perform the resummation of soft gluons at next-to-leading-logarithmic (NLL) accuracy for all possible production processes in the framework of the Minimal Supersymmetric Standard Model. In particular we consider pair production processes of mass-degenerate light-flavour squarks and gluinos as well as the pair production of top squarks and non-mass-degenerate bottom squarks. We present analytical results for all considered processes including the soft anomalous dimensions. Moreover numerical predictions for total cross sections and transverse-momentum distributions for both the Large Hadron Collider (LHC) and the Tevatron are presented. We provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions. The inclusion of NLL corrections leads to a considerable reduction of the theoretical uncertainty due to scale variation and to an enhancement of the next-to-leading order (NLO) cross section predictions. The size of the soft-gluon corrections and the reduction in the scale uncertainty are most significant for processes involving gluino production. At the LHC, where the sensitivity to squark and gluino masses ranges up to 3 TeV, the corrections due to NLL resummation over and above the NLO predictions can be as high as 35 % in the case of gluino-pair production, whereas at the Tevatron, the NLL corrections are close to 40 % for squark-gluino final states with supersymmetric particle masses around 500 GeV
Improved squark and gluino mass limits from searches for supersymmetry at hadron colliders
Squarks and gluinos have been searched for at hadron colliders in events with
multiple jets and missing transverse energy. No excess has been observed to
date, and from a comparison of experimental cross section limits and
theoretical cross section predictions one can deduce lower bounds on the squark
and gluino masses. We present an improved analysis of squark and gluino mass
bounds which is based on state-of-the-art cross section calculations including
the summation of large threshold corrections. For illustration, we consider
experimental data obtained by the CDF collaboration at the Fermilab Tevatron
and discuss the impact of the improved cross section predictions on the squark
and gluino mass limits.Comment: 10 pages, 6 figures; removed redundant figure
Squark and gluino hadroproduction
We review the theoretical status of squark and gluino hadroproduction and
provide numerical predictions for all squark and gluino pair-production
processes at the Tevatron and at the LHC, with a particular emphasis on
proton-proton collisions at 7 TeV. Our predictions include next-to-leading
order supersymmetric QCD corrections and the resummation of soft gluon emission
at next-to-leading-logarithmic accuracy. We discuss the impact of the
higher-order corrections on total cross sections, and provide an estimate of
the theoretical uncertainty due to scale variation and the parton distribution
functions.Comment: 30 pages, 17 figures, invited review article for Int. J. Mod. Phys.
NNLL resummation for squark-antisquark pair production at the LHC
We consider the resummation of soft gluon emission for squark-antisquark
pair-production at the LHC at next-to-next-to-leading-logarithmic (NNLL)
accuracy in the framework of the minimal supersymmetric standard model. We
present the analytical ingredients needed for the calculation and provide
numerical predictions for the LHC at centre-of-mass energies of 7 and 14 TeV.
We find a significant reduction in the scale uncertainty and a considerable
increase in the prediction of the total cross section. Compared to the
next-to-leading order prediction, the corrections increase the cross section by
up to 30% for 1.5 TeV squarks at a centre-of-mass energy of 7 TeV.Comment: 22 pages, 5 figure